Relay adhesion detection method, detection circuit, battery management system and electric vehicle

Abstract

The embodiment of the invention discloses a relay adhesion detection method and circuit, a battery management system and an electric vehicle. The method comprises the following steps: after the battery management system is electrified and initialized, acquiring a first voltage of a negative electrode end of a battery, delaying a first time when the first voltage is greater than or equal to a preset second voltage and less than or equal to a preset third voltage, and acquiring a fourth voltage of the negative electrode end again, and whether the relay is adhered is determined according to the first voltage and the fourth voltage, so that whether the total negative high-voltage relay is in an adhesion state can be accurately judged, the situation that the battery management system misjudges adhesion possibly caused when the power battery is charged and awakened can be avoided, and normal work of the power battery and the whole vehicle can be ensured.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a relay adhesion detection method, detection circuit, battery management system, and electric vehicle. Background Technology

[0002] In the high-voltage system of electric vehicles, the main negative high-voltage relay is one of the key components. It is primarily used to control the on / off state of the negative side circuit of the power battery and can work in conjunction with the main positive relay to ensure the power battery can safely supply power to the vehicle. The proper functioning of the main negative high-voltage relay is crucial to the safety performance of electric vehicles. Therefore, correctly and stably detecting the relay's status can prevent the failure to promptly report faults and take corrective action when a relay malfunctions, thus eliminating unsafe factors within the power battery. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this application provides a relay sticking detection method, detection circuit, battery management system, and electric vehicle. It can accurately determine whether the main negative high voltage relay is in a sticking state, thereby avoiding the battery management system's misjudgment of sticking when the power battery is being charged and woken up, thus ensuring the normal operation of the power battery and the vehicle.

[0004] To address the aforementioned problems, in a first aspect, this application provides a method for detecting relay adhesion, wherein the relay is located at the negative terminal of a battery and is configured to control the on / off state of the battery's charging and discharging circuit; the relay adhesion detection method includes:

[0005] If the battery management system of the battery is powered on and completes initialization, the first voltage of the negative terminal is obtained;

[0006] If the first voltage is greater than or equal to a preset second voltage and less than or equal to a preset third voltage, the fourth voltage at the negative terminal is obtained after a preset first time.

[0007] Determine whether the relay is stuck based on the first voltage and the fourth voltage.

[0008] Furthermore, after obtaining the first voltage at the negative terminal, the process also includes:

[0009] If the first voltage is less than the second voltage or the first voltage is greater than the third voltage, it is determined that the relay is not stuck.

[0010] Furthermore, determining whether the relay is stuck based on the first voltage and the fourth voltage includes:

[0011] Generate a first voltage difference between the first voltage and the fourth voltage;

[0012] If the first voltage difference is greater than the preset fifth voltage, it is determined that the relay is not stuck.

[0013] Furthermore, after generating the first voltage difference between the first voltage and the fourth voltage, the process also includes:

[0014] If the first voltage difference is less than or equal to the fifth voltage, the sixth voltage at the negative terminal is obtained after a preset second time.

[0015] Determine whether the relay is stuck based on the first voltage and the sixth voltage.

[0016] Furthermore, the relay adhesion detection method also includes:

[0017] If the relay is in the open state, the seventh voltage at the negative terminal is obtained;

[0018] If the relay is in the closed state, the second and third voltages are determined based on the seventh voltage.

[0019] Secondly, this application also provides a detection circuit, which is applied to the relay adhesion detection method of the first aspect;

[0020] One end of the detection circuit is electrically connected to one end of the relay, and the other end of the relay is electrically connected to the negative terminal.

[0021] Furthermore, in the detection circuit provided in this application, the detection circuit includes:

[0022] The first resistor is electrically connected at one end to the relay.

[0023] The second resistor has one end connected to a voltage source and the other end electrically connected to the other end of the first resistor to form a node.

[0024] The sampling chip includes a power supply end and a sampling end; the power supply end is connected to a voltage source, and the sampling end is electrically connected to a node.

[0025] Furthermore, in the detection circuit provided in this application, the detection circuit also includes a diode;

[0026] The positive terminal of the diode is electrically connected to one end of the first resistor, and the negative terminal of the diode is electrically connected to one end of the relay.

[0027] Thirdly, this application also provides a battery management system that includes the detection circuit provided in the second aspect.

[0028] Fourthly, this application also provides an electric vehicle, a charging and discharging port for the electric vehicle, the electric vehicle including the detection circuit provided in the second aspect, or the battery management system provided in the third aspect.

[0029] The relay sticking detection method provided in this application acquires the first voltage of the negative terminal of the battery after the battery management system is powered on and initialized. When the first voltage is greater than or equal to a preset second voltage and less than or equal to a preset third voltage, a first delay is made, and a fourth voltage of the negative terminal is acquired again. The method determines whether the relay is sticking based on the first voltage and the fourth voltage, thereby accurately determining whether the total negative high voltage relay is in a sticking state. This can avoid the battery management system from misjudging the sticking situation when the power battery is woken up during charging, thus ensuring that the power battery and the vehicle work normally. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A schematic block diagram of the detection circuit provided in an embodiment of this application;

[0032] Figure 2 This is a schematic diagram of the first process of the relay adhesion detection method provided in the embodiments of this application;

[0033] Figure 3 This is a schematic diagram of the second process of the relay adhesion detection method provided in the embodiments of this application;

[0034] Figure 4 This is a schematic diagram of the third process of the relay adhesion detection method provided in the embodiments of this application;

[0035] Figure 5 This is a schematic diagram of the fourth process of the relay adhesion detection method provided in the embodiments of this application. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0038] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0039] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0040] Furthermore, in this application, unless otherwise explicitly specified or limited in the embodiments, the terms "installation," "connection," "joining," and "fixing" appearing in the embodiments should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral part; it can also be a mechanical connection, an electrical connection, etc. Of course, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication between two components, or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific implementation.

[0041] In related technologies, there are various detection methods and strategies for detecting the sticking of the main negative relay of the power battery. However, when performing the sticking detection of the main negative relay of the power battery on the high-voltage circuit of the charging and discharging port, it is easily affected by the charging gun. This may cause the voltage value of the main negative relay of the power battery detected by the battery management system to be abnormal, resulting in a false judgment of sticking fault, which will prevent the vehicle from being connected to high voltage and affect the use by customers.

[0042] To address this, this application provides a relay sticking detection method, detection circuit, battery management system, and electric vehicle. After the battery management system is powered on and initialized, the first voltage of the negative terminal of the battery is acquired. When the first voltage is greater than or equal to a preset second voltage and less than or equal to a preset third voltage, a first delay is applied, and a fourth voltage of the negative terminal is acquired again. Based on the first voltage and the fourth voltage, it is determined whether the relay is sticking. This allows for accurate judgment of whether the total negative high voltage relay is in a sticking state, thereby avoiding potential misjudgment of sticking by the battery management system during power battery charging wake-up, and ensuring the normal operation of the power battery and the vehicle.

[0043] To facilitate understanding, the detection circuit will be introduced first, followed by a detailed explanation of the relay sticking detection method. This detection circuit can be part of the battery management system or the electric vehicle itself. The relay sticking detection method can be executed by the battery management system or by the vehicle's controller.

[0044] Please see Figure 1 , Figure 1 This is a schematic block diagram of the detection circuit 10 provided in an embodiment of this application. Figure 1 As shown, this application provides a detection circuit 10, which is used for detecting the adhesion of a relay S1. One end of the detection circuit 10 is electrically connected to one end of the relay S1, and the other end of the relay S1 is electrically connected to the negative terminal BAT-.

[0045] In this embodiment, the battery includes a positive terminal BAT+ and a negative terminal BAT-. The detection circuit 10 is provided with a detection terminal, which can be connected to one end of the relay S1. At the same time, the detection circuit 10 also needs to share a common ground with the battery. Thus, when the relay S1 is in the open state, the voltage of the negative terminal BAT- of the battery can be collected to obtain the initial voltage. Then, after the relay S1 is closed, a first voltage can be obtained. Then, the first voltage is compared with the initial voltage, thereby determining whether the relay S1 of the negative terminal BAT- of the battery is stuck.

[0046] In addition, this application can also determine whether the first voltage is between a preset second voltage and a preset third voltage, so as to determine whether the relay S1 of the negative terminal BAT- of the battery is stuck.

[0047] Furthermore, in order to improve the accuracy of detecting whether the relay S1 at the negative terminal BAT- of the battery is stuck, this application may also perform voltage sampling again at the negative terminal BAT- after a preset first time, i.e. after a first time delay, to determine whether the relay S1 at the negative terminal BAT- of the battery is stuck.

[0048] The detection circuit 10 provided in this application can acquire the first voltage of the negative terminal BAT- of the battery after the battery management system is powered on and initialized. When the first voltage is greater than or equal to a preset second voltage and less than or equal to a preset third voltage, it delays for a first time and acquires the fourth voltage of the negative terminal BAT- again. Based on the first voltage and the fourth voltage, it determines whether the relay S1 is stuck, thereby accurately judging whether the total negative high voltage relay is in a stuck state. This can avoid the BMS misjudging the sticking situation that may occur when the power battery is charging and woken up, thus ensuring that the power battery and the whole vehicle work normally.

[0049] In some embodiments, such as Figure 1As shown, the detection circuit 10 includes:

[0050] The first resistor R1 is electrically connected to one end of the relay S1;

[0051] The second resistor R2 has one end connected to a voltage source and the other end electrically connected to the other end of the first resistor R1 to form a node.

[0052] The sampling chip 110 includes a power supply end and a sampling end; the power supply end is connected to a voltage source, and the sampling end is electrically connected to a node.

[0053] In this embodiment, the sampling chip 110 is understood as the main control board of the battery management system. An ADC acquisition module can be installed within the sampling chip 110. One pin of the ADC acquisition module can serve as the sampling terminal of the sampling chip 110. The sampling terminal can be electrically connected between a first resistor R1 and a second resistor R2. Simultaneously, one end of the series connection between the first resistor R1 and the second resistor R2 is electrically connected to one end of the relay S1, and the other end is connected to the power supply terminal of the sampling chip 110 via a voltage source, which can be a 5V voltage source. The resistance values ​​of both the first resistor R1 and the second resistor R2 can be 2040KΩ.

[0054] Furthermore, in some embodiments, such as Figure 1 As shown, the detection circuit 10 also includes a diode D1; wherein the positive terminal of the diode D1 is electrically connected to one end of the first resistor R1, and the negative terminal of the diode D1 is electrically connected to one end of the relay S1.

[0055] In this embodiment, the positive terminal of diode D1 is electrically connected to one end of the first resistor R1, and the negative terminal of diode D1 is electrically connected to one end of the relay S1. It can be used as a reverse connection protection device to prevent current backflow during battery discharge, which could damage the sampling chip 110.

[0056] It is understood that the detection circuit 10 provided in the above embodiments is merely an example. The detection circuit 10 described in the embodiments of this application is to more clearly illustrate the technical solutions of the embodiments of this application, and does not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of the system and the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems. Detailed descriptions will follow.

[0057] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. The relay adhesion detection method described below will be explained in detail. Furthermore, the relay adhesion detection method provided in this application can be executed by a battery management system.

[0058] Please see Figure 2 , Figure 2 This is a schematic diagram of the first process of the relay adhesion detection method provided in an embodiment of this application. Figure 2 As shown, this application provides a relay adhesion detection method, wherein the relay S1 is located at the negative terminal BAT- of the battery, and the relay S1 is configured to control the on / off state of the battery's charging and discharging circuit.

[0059] The relay adhesion detection method provided in this application includes steps S110, S120 and S130.

[0060] S110. If the battery management system of the battery is powered on and completes initialization, obtain the first voltage of the negative terminal BAT-.

[0061] In this embodiment, the battery management system's power-on initialization can be understood as the battery management system being woken up and entering initialization mode. At this time, the relay S1 at the negative terminal BAT- of the battery is in the open state by default. The power-on process of the battery management system can be specifically understood as the process of the battery's total negative high-voltage relay (the relay S1 at the negative terminal BAT-) and the battery's total positive high-voltage relay closing sequentially; or the process of the battery's total negative high-voltage relay (the relay S1 at the negative terminal BAT-) and the pre-charge circuit at the positive terminal BAT+ closing sequentially, and after the pre-charge circuit at the positive terminal BAT+ of the battery completes charging, the process of closing the battery's total positive high-voltage relay S1 and opening the pre-charge circuit.

[0062] Specifically, after the battery management system completes its initialization upon power-up, the relay S1 at the negative terminal BAT- of the battery is in the open state by default. At this time, the detection circuit 10 collects the first voltage at the negative terminal BAT- and determines whether the first voltage is between the second and third voltages to determine whether the relay S1 is stuck. If the first voltage is between the second and third voltages, it can be determined that the relay S1 is not stuck; if the first voltage is not between the second and third voltages, it can be determined that the relay S1 is stuck. The second and third voltages can be preset according to the actual application; for example, the second voltage can be 2.7V or 2.4V, and the third voltage can be 2.85V.

[0063] S120. If the first voltage is greater than or equal to the preset second voltage and less than or equal to the preset third voltage, after a preset first time, obtain the fourth voltage of the negative terminal BAT-.

[0064] In this embodiment, if the first voltage is between the second and third voltages, it can be determined that relay S1 has a high probability of sticking. To further determine whether relay S1 has already stuck, this application can collect the voltage of the negative terminal BAT- again after the first time interval, i.e., the fourth voltage. By judging whether the fourth voltage is between the second and third voltages, it can be determined whether relay S1 has already stuck. The first time interval can be 200ms.

[0065] In some embodiments, after obtaining the first voltage at the negative terminal BAT-, the method further includes: if the first voltage is less than the second voltage or the first voltage is greater than the third voltage, determining that the relay S1 is not stuck.

[0066] Specifically, this application determines whether relay S1 is stuck by judging whether the first voltage is between the second voltage and the third voltage. If it is determined that the first voltage is not between the second voltage and the third voltage, it can be determined that relay S1 is not stuck. At this time, the battery management system can continue to perform the power-on operation until the system where the battery is located completes the power-on operation and performs charging and discharging.

[0067] S130. Determine whether relay S1 is stuck based on the first voltage and the fourth voltage.

[0068] In this embodiment, the present application can also determine whether the relay S1 at the negative terminal BAT- of the battery is stuck by judging the voltage difference between the first voltage and the fourth voltage. Specifically, after obtaining the fourth voltage, the voltage difference between the two voltages is determined based on the first voltage and the fourth voltage, and it is determined whether the voltage difference is greater than a preset fifth voltage to determine whether the relay S1 is stuck.

[0069] Furthermore, in some embodiments, such as Figure 3 As shown, determining whether relay S1 is stuck based on the first voltage and the fourth voltage includes:

[0070] S131, Generate a first voltage difference between the first voltage and the fourth voltage;

[0071] S132. If the first voltage difference is greater than the preset fifth voltage, it is determined that the relay S1 is not stuck.

[0072] In the design of the electric vehicle containing the battery, the charging and discharging ports of the electric vehicle are the same, meaning the charging and discharging circuits of the battery are the same. When the battery is charged using a charging gun, the voltage rise and discharge during insulation detection by the charging gun directly affect the state of the downstream detection point of the relay S1 at the negative terminal BAT- of the battery. Consequently, at certain times, the first voltage collected by the detection circuit 10 happens to be between the second and third voltages, leading to a false judgment of adhesion.

[0073] However, comparing the actual performance of the two scenarios—real adhesion and the influence of the charging gun—it can be found that when the relay S1 at the negative terminal of the battery truly adheres, the voltage collected by the detection circuit 10 will be fixed at a point between the second and third voltages, and the voltage fluctuation will not exceed the preset fifth voltage. In contrast, under the influence of the charging gun, the voltage collected by the detection circuit 10 will drop from the initial voltage to the fourth voltage, and fluctuate within a preset first time interval, exhibiting a significant difference.

[0074] Therefore, this application can generate a first voltage difference between a first voltage and a fourth voltage, and determine whether the first voltage difference is greater than a preset fifth voltage to determine whether the relay S1 is stuck. Specifically, if the first voltage difference is greater than the fifth voltage, it can be determined that the relay S1 is not stuck; if the first voltage difference is less than or equal to the fifth voltage, it can be determined that the relay S1 is stuck. The fifth voltage can be 5mV.

[0075] In some embodiments, such as Figure 4 As shown, after generating the first voltage difference between the first voltage and the fourth voltage, the process further includes:

[0076] S133. If the first voltage difference is less than or equal to the fifth voltage, after a preset second time, obtain the sixth voltage of the negative terminal BAT-.

[0077] S134. Determine whether relay S1 is stuck based on the first voltage and the sixth voltage.

[0078] In this embodiment, to further accurately determine whether relay S1 is stuck, after the first voltage difference is less than or equal to the fifth voltage, a second time delay is applied to collect the voltage at the negative terminal BAT- again, i.e., the sixth voltage, and obtain the second voltage difference between the sixth voltage and the first voltage. At the same time, it is determined whether the second voltage difference is greater than the fifth voltage to determine whether relay S1 is stuck. The second time can be 200ms.

[0079] Specifically, if the second voltage difference is greater than the fifth voltage, it can be determined that the relay S1 is not stuck; if the second voltage difference is less than or equal to the fifth voltage, it can be determined that the relay S1 is stuck.

[0080] In addition, this application can repeat steps S133 and S134 five times to determine adhesion, so as to avoid false voltage detection caused by actual adhesion and charging connection of relay S1, thereby effectively and reliably detecting the true adhesion state and greatly avoiding false detection of adhesion faults.

[0081] In some embodiments, such as Figure 5 As shown, the relay detection method also includes steps S210 and S220.

[0082] S210. If relay S1 is in the open state, obtain the seventh voltage at the negative terminal BAT-;

[0083] S220. If relay S1 is in the closed state, determine the second voltage and the third voltage based on the seventh voltage.

[0084] In this embodiment, if the application adopts Figure 1 The detection circuit 10 shown performs relay S1 adhesion detection. When relay S1 at the negative terminal BAT- of the battery is in the open state, the detection circuit 10 is in a floating state. At this time, the initial voltage collected by the detection circuit 10, i.e., the seventh voltage, can be the voltage of the voltage source, i.e., 5V. If relay S1 at the negative terminal BAT- of the battery is in the closed state, the detection circuit 10 can collect multiple voltages. These multiple voltages can be determined by the forward voltage drop of diode D1. At this time, the minimum and maximum voltages can be determined from the multiple voltages and used as the second and third voltages, respectively.

[0085] For example, if the resistance values ​​of the first resistor R1 and the second resistor R2 are both 2040KΩ, the seventh voltage is 5V, and the forward voltage drop of diode D1 is between 0.4V and 0.7V, and if the relay S1 at the negative terminal BAT- of the battery is closed, the formula for calculating the voltage U collected at this time can be U = (5V - forward voltage drop) / 2 + forward voltage drop = 2.7V to 2.85V. In this case, the second voltage can be 2.7V, and the third voltage can be 2.85V. Alternatively, to more accurately determine whether the relay S1 is stuck, the second voltage can also be 2.4V.

[0086] The relay sticking detection method provided in this application obtains the first voltage of the negative terminal BAT- of the battery after the battery management system is powered on and initialized. When the first voltage is greater than or equal to a preset second voltage and less than or equal to a preset third voltage, a first delay is made, and a fourth voltage of the negative terminal BAT- is obtained again. The method determines whether the relay S1 is sticking based on the first voltage and the fourth voltage, thereby accurately determining whether the total negative high voltage relay is in a sticking state. This can avoid the battery management system from misjudging the sticking situation when the power battery is woken up during charging, thus ensuring the normal operation of the power battery and the vehicle.

[0087] In some embodiments, this application also provides a battery management system, which includes the detection circuit 10 provided in this application.

[0088] In some embodiments, this application also provides an electric vehicle, the electric vehicle having a charging and discharging port, the electric vehicle including the detection circuit 10 provided in this application, or the battery management system provided in this application.

[0089] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A relay adhesion detection method, characterized in that: The relay is disposed at the negative terminal of the battery, and the relay is configured to control the on-off of the charging and discharging circuit of the battery; the method comprises: If the battery management system of the battery is powered on and initialized, obtaining a first voltage at the negative terminal; If the first voltage is greater than or equal to a preset second voltage and less than or equal to a preset third voltage, after a preset first time, a fourth voltage of the negative terminal is obtained; Whether the relay is stuck is determined according to the first voltage and the fourth voltage.

2. The relay adhesion detection method according to claim 1, characterized in that: After obtaining the first voltage of the negative terminal, the method further includes: If the first voltage is less than the second voltage or the first voltage is greater than the third voltage, it is determined that the relay is not stuck.

3. The relay adhesion detection method according to claim 1, characterized in that: The determining whether the relay is stuck according to the first voltage and the fourth voltage includes: generating a first voltage difference between the first voltage and the fourth voltage; If the first voltage difference is greater than a preset fifth voltage, it is determined that the relay is not stuck.

4. The relay adhesion detection method according to claim 3, characterized in that: After generating a first voltage difference between the first voltage and the fourth voltage, the method further includes: If the first voltage difference is less than or equal to the fifth voltage, after a preset second time, obtaining a sixth voltage at the negative terminal; Whether the relay is stuck is determined according to the first voltage and the sixth voltage.

5. The relay adhesion detection method according to any one of claims 1 to 4, characterized in that: The method further comprises: If the relay is in an off state, obtaining a seventh voltage at the negative terminal; If the relay is in a closed state, the second voltage and the third voltage are determined according to the seventh voltage.

6. A detection circuit, characterized in that: A relay adhesion detection method as claimed in any one of claims 1 to 5; Wherein, one end of the detection circuit is electrically connected to one end of the relay, and the other end of the relay is electrically connected to the negative terminal.

7. The detection circuit according to claim 6, characterized in that: The detection circuit comprises: a first resistor, one end of which is electrically connected to one end of the relay; a second resistor, one end of the second resistor being connected to a voltage source, and the other end of the second resistor being electrically connected to the other end of the first resistor to form a node; The sampling chip comprises a power supply end and a sampling end; the power supply end is connected to the voltage source, and the sampling end is electrically connected to the node.

8. The detection circuit according to claim 7, characterized in that: The detection circuit also includes a diode; The anode of the diode is electrically connected to one end of the first resistor, and the cathode of the diode is electrically connected to one end of the relay.

9. A battery management system, characterized in that: The detection circuit comprises the detection circuit described in any one of claims 6-8.

10. An electric vehicle, characterized in that: The charging and discharging port of the electric vehicle comprises the detection circuit described in any one of claims 6 to 8, or the battery management system described in claim 9.

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