Relay contact detection circuit and battery management system

Abstract

The utility model relates to a relay contact detection circuit and a battery management system, the relay contact detection circuit comprises a first detection loop and a second detection loop which are connected with each other, the first detection loop comprises a first voltage source, a first contact pair, a first sampling switch and a first sampling unit which are connected in series, and the first contact pair is connected to the positive electrode output end of the first voltage source in series; the second detection loop comprises a second voltage source, a second sampling unit, a second sampling switch and a second contact pair which are connected in series, the second contact pair is connected to the negative electrode output end of the first voltage source in series, and the negative electrode output end of the second voltage source is connected with the negative electrode output end of the first voltage source. The two detection circuits respectively take mutually independent battery packs as reference power supplies, so that the stability of voltage values of sampling points is ensured, and the stability and the reliability of calculation are improved.

Description

Technical Field

[0001] This application relates to the field of relay sticking detection, and in particular to a relay contact detection circuit and a battery management system. Background Technology

[0002] Energy storage battery systems include modules such as battery modules and high-voltage boxes. As the application of energy storage battery systems becomes increasingly widespread, the safety requirements for these systems are also constantly rising, especially the determination of whether relays are stuck together, which is crucial for system safety.

[0003] In energy storage battery systems, existing technologies require the use of relays with auxiliary contacts to detect whether the main contacts are stuck together. However, relays with auxiliary contacts are expensive and have low detection reliability. Utility Model Content

[0004] Therefore, it is necessary to provide a relay contact detection circuit, method, and battery management system to address the above-mentioned technical problems. This eliminates the need for relays with auxiliary contacts, reducing costs and significantly improving detection reliability.

[0005] In a first aspect, this utility model provides a relay contact detection circuit, including a first detection circuit and a second detection circuit connected to each other. The first detection circuit includes a first voltage source, a first contact pair, a first sampling switch, and a first sampling unit connected in series, wherein the first contact pair is connected in series to the positive output terminal of the first voltage source. The second detection circuit includes a second voltage source, a second sampling unit, a second sampling switch, and a second contact pair connected in series, wherein the second contact pair is connected in series to the negative output terminal of the first voltage source, and the negative output terminal of the second voltage source is connected to the negative output terminal of the first voltage source.

[0006] The first sampling unit is used to acquire a first sampling voltage signal when the first sampling switch is closed, so as to determine whether the first contact pair is stuck together after being cut off; the second sampling unit is used to acquire a second sampling voltage signal when the second sampling switch is closed, so as to determine whether the second contact pair is stuck together after being cut off.

[0007] According to one embodiment of this application, the first sampling unit includes a first voltage divider element and a first sampling element connected in series; the second sampling unit includes a second voltage divider element and a second sampling element connected in series; the sampling point of the first sampling voltage signal is the connection point of the first voltage divider element and the first sampling element; the sampling point of the second sampling voltage signal is the connection point of the second voltage divider element and the second sampling element.

[0008] According to one embodiment of this application, the first sampling switch and the second sampling switch are mechanical switches or electronic switches; and / or, the first voltage divider element and the second voltage divider element are a voltage divider resistor or a plurality of voltage divider resistors connected in series; and / or, the first sampling element and the second sampling element are a sampling resistor or a plurality of sampling resistors connected in series.

[0009] According to one embodiment of this application, the negative output terminal of the first voltage source is grounded.

[0010] According to one embodiment of this application, the first voltage source is a battery pack consisting of multiple batteries connected in series.

[0011] According to one embodiment of this application, the first contact pair and the second contact pair are redundant contact pairs.

[0012] On the other hand, this utility model embodiment provides a battery management system, including the aforementioned relay contact detection circuit and a controller electrically connected to the relay contact detection circuit; the controller receives a first sampling voltage signal sent by the relay contact detection circuit after the first sampling switch is closed, and determines whether the first contact pair is stuck after being cut off based on the first sampling voltage signal; and the controller receives a second sampling voltage signal sent by the relay contact detection circuit after the second sampling switch is closed, and determines whether the second contact pair is stuck after being cut off based on the second sampling voltage signal.

[0013] According to one embodiment of this application, the controller is configured to receive the first sampling voltage signal after controlling the second sampling switch to open and the first sampling switch to close; the controller is also configured to receive the second sampling voltage signal after controlling the first sampling switch to open and the second sampling switch to close.

[0014] According to one embodiment of this application, the controller obtains a first detection voltage based on the first sampling voltage signal, and determines whether the first contact pair is stuck together after being cut based on the first detection voltage; and the controller obtains a second detection voltage based on the second sampling voltage signal, and determines whether the second contact pair is stuck together after being cut based on the second detection voltage.

[0015] According to one embodiment of this application, the first voltage source is connected to the load; the first detected voltage is the voltage at the connection point between the load and the first contact pair; the second detected voltage is the voltage divided by the second voltage source after being divided by the second sampling unit.

[0016] The first and second detection circuits of this application use independent battery packs as reference power sources, which ensures the stability of the voltage value at the sampling point and improves the stability and reliability of the calculation. Even if there is voltage at the load before the energy storage battery system is powered on with high voltage, it will not lead to misjudgment of the relay sticking state.

[0017] Furthermore, this application detects the first sampling voltage signal (i.e., the voltage division of the first sampling element) at the first sampling point by disconnecting the second sampling switch and closing the first sampling switch. A first detection voltage is calculated from the first sampling voltage signal, and the first detection voltage is used to determine whether the first contact pair is stuck. Similarly, by disconnecting the first sampling switch and closing the second sampling switch, a second detection voltage (the voltage division of the second sampling element) is obtained, and the second detection voltage is used to determine whether the second contact pair is stuck. In other words, the entire detection process only requires controlling the opening and closing of two sampling switches, without the need for auxiliary contacts or repeated opening and closing of other relays, to determine whether the relay under test is stuck. This means that using the solution of this application eliminates the need for relays with auxiliary contacts in the energy storage battery system, reducing relay costs and improving detection reliability. Attached Figure Description

[0018] Figure 1 This is a structural block diagram of a relay contact detection circuit in an example embodiment of this application;

[0019] Figure 2 This is a schematic diagram of a relay contact detection circuit in an example embodiment of this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the application is described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0021] like Figure 1 As shown in the figure, this application discloses a relay contact detection circuit, which is applied in a scenario including a first contact pair S2 and a second contact pair S3, to detect whether the first contact pair S2 and the second contact pair S3 are stuck together, thereby reducing the cost of high-voltage relays in energy storage battery systems.

[0022] It should be noted that in other embodiments of this application, the first contact pair S2 and the second contact pair S3 are both conventional relays without auxiliary contacts.

[0023] In relays with auxiliary contacts, the auxiliary contacts are composed of limit switches. Limit switches are mechanical structures with a limited lifespan. Furthermore, in relays with auxiliary contacts, the main contacts and auxiliary contacts often do not open or close simultaneously. For example, the main contacts may stick together, causing the auxiliary contacts to open, or vice versa. This often reduces the reliability of the relay test results. The relays under test in this application are all conventional relays without auxiliary contacts, thus improving the reliability of the test results.

[0024] The relay contact detection circuit includes a first detection circuit and a second detection circuit. For example... Figure 1 As shown, the first detection circuit is used to detect the adhesion of the first contact to S2, and the second detection circuit is used to detect the adhesion of the second contact to S3.

[0025] The first detection circuit includes: a first voltage source V, a first contact pair S2, a first sampling switch S1, and a first sampling unit connected in series, wherein the first contact pair S2 is connected in series to the positive output terminal of the first voltage source V; the second detection circuit includes a second voltage source V3, a second sampling unit, a second sampling switch S4, and a second contact pair S3 connected in series, wherein the second contact pair S3 is connected in series to the negative output terminal of the first voltage source V, and the negative output terminal of the second voltage source V3 is connected to the negative output terminal of the first voltage source V; the first sampling unit is used to acquire a first sampling voltage signal V1 when the first sampling switch S1 is closed, to determine whether there is adhesion after the first contact pair S2 is cut off; the second sampling unit is used to acquire a second sampling voltage signal V2 when the second sampling switch S4 is closed, to determine whether there is adhesion after the second contact pair S3 is cut off.

[0026] In other embodiments of this application, such as Figure 2 As shown, the first sampling unit includes a first voltage divider element R2 and a first sampling element R1 connected in series; the second sampling unit includes a second voltage divider element R3 and a second sampling element R4 connected in series; the sampling point of the first sampled voltage signal V1 is the connection point of the first voltage divider element R2 and the first sampling element R1; the sampling point of the second sampled voltage signal V2 is the connection point of the second voltage divider element R3 and the second sampling element R4.

[0027] It should be noted that the first voltage divider element R2 and the second voltage divider element R3 can be a voltage divider resistor or multiple voltage divider resistors connected in series / parallel. Similarly, the first sampling element R1 and the second sampling element R4 can also be a sampling resistor or multiple sampling resistors connected in series. In this embodiment, the first voltage divider element R2 and the second voltage divider element R3 are each a voltage divider resistor, and the first sampling element R1 and the second sampling element R4 are each a sampling resistor, as an example for illustration.

[0028] It should be noted that the first sampling switch S1 and the second sampling switch S4 are mechanical switches or electronic switches; and / or, the first voltage divider element R2 and the second voltage divider element R3 are one voltage divider resistor or multiple voltage divider resistors connected in series; and / or, the first sampling element R1 and the second sampling element R4 are one sampling resistor or multiple sampling resistors connected in series.

[0029] Specifically, one end of the first contact pair S2 is connected to the positive output terminal of the first voltage source V, and the other end is connected to the first terminal P+ of the external load. One end of the first sampling switch S1 is connected to the first terminal P+ of the external load, and the other end is connected to one end of the first voltage divider element R2. The other end of the first voltage divider element R2 is connected to one end of the first sampling element R1, and the other end of the first sampling element R1 is connected to the negative output terminal of the first voltage source V. This first detection circuit has a first voltage sampling point used to acquire the first sampling voltage signal V1. The first voltage sampling point is the connection point of the first voltage divider element R2 and the first sampling element R1, and the first sampling voltage signal V1 is the voltage divided by the first sampling element R1.

[0030] Specifically, one end of the second voltage divider element R3 is connected to the positive output terminal of the second voltage source V3, and the other end is connected to one end of the second sampling element R4. The other end of the second sampling element R4 is connected to one end of the second sampling switch S4. The other end of the second sampling switch S4 is connected to one end of the second contact pair S3 and to the second terminal P- of the external load. The other end of the second contact pair S3 and the negative output terminal of the second voltage source V3 are connected to the negative output terminal of the first voltage source V. This second detection circuit has a second voltage sampling point used to acquire the second detection voltage U3. The second voltage sampling point is the connection point of the second voltage divider element R3 and the second sampling element R4, and the second detection voltage U3 is the voltage divided by the second sampling element R4.

[0031] It should be noted that the first sampling switch S1 and the second sampling switch S4 in this embodiment are electronic switches composed of one or more MOS devices. The electronic switches can be opened and closed by controlling the level of the gate position. This embodiment does not limit this.

[0032] Preferably, in order to reduce signal interference in the circuit, the negative output terminal of the first voltage source V is grounded.

[0033] In energy storage battery systems, to ensure the battery system can be shut down normally, two sets of contact pairs are generally set up, one positive and one negative. These two sets of contact pairs are redundant; that is, in this embodiment, the first contact pair S2 and the second contact pair S3 are redundant. When one contact pair fails, the other contact pair continues to operate normally and promptly disconnects the circuit. In some embodiments, these two sets of contact pairs belong to two different relays. Preferably, the relay to which the first contact pair S2 belongs is the main positive relay, and the relay to which the second contact pair S3 belongs is the main negative relay. It is understood that the main positive relay and the main negative relay are redundant.

[0034] The relay contact detection circuit of this application controls the first sampling switch S1 to close, detects the first sampling voltage signal V1 at the first sampling point, calculates the first detection voltage U1 based on the first sampling voltage signal V1, and determines whether the first contact pair S2 is stuck by the value of U1. Similarly, by controlling the second sampling switch S4 to close, the second detection voltage U3 is obtained, and determines whether the second contact pair S3 is stuck by the second detection voltage U3.

[0035] Furthermore, in this embodiment of the invention, the first voltage source V can be an energy storage battery pack in an energy storage battery system, which can supply power to an external load. The first voltage source V can be a single energy storage battery, multiple energy storage batteries, or a battery pack composed of multiple batteries connected in series, depending on the application scenario requirements. This embodiment does not impose any limitations on this.

[0036] Furthermore, in this embodiment, the second voltage source V3 is an additional battery pack added to the energy storage battery system. This second voltage source V3 is only used to provide a reference power supply for the second detection circuit; that is, the second voltage source V3 can provide a stable reference voltage for the second detection circuit without needing to supply power to an external load. Therefore, the second voltage source V3 can be a low-power battery. For example, if the second voltage source V3 is a reference power supply providing 5V, the detection of the second contact pair S3 can be achieved. The second voltage source V3 can be a single battery or can include multiple batteries.

[0037] Since the first voltage source V and the second voltage source V3 are independent power sources, and both the first voltage source V and the second voltage source V3 can provide a stable reference voltage for their respective detection circuits, the stability of the voltage values ​​at the first sampling point and the second sampling point is ensured. Even if there is voltage at the load before the energy storage battery system is powered on at high voltage, it will not lead to misjudgment of the relay sticking state.

[0038] It should be noted that in other embodiments of this application, a battery management system is provided, including the relay contact detection circuit described above, and a controller electrically connected to the relay contact detection circuit; the controller receives a first sampling voltage signal V1 sent by the relay contact detection circuit after the first sampling switch S1 is closed, and determines whether there is adhesion after the first contact pair S2 is cut off based on the first sampling voltage signal V1; and the controller receives a second sampling voltage signal V2 sent by the relay contact detection circuit after the second sampling switch S4 is closed, and determines whether there is adhesion after the second contact pair S3 is cut off based on the second sampling voltage signal V2.

[0039] It should be noted that the first voltage source V is connected to the load, the first detection voltage U1 is the voltage at the connection point between the load and the first contact pair S2; the second detection voltage U3 is the voltage divided by the second voltage source V3 after being divided by the second sampling unit, that is, the voltage value sampled by the second sampling element R4.

[0040] In another embodiment of this application, the controller is configured to receive a first sampled voltage signal V1 after controlling the second sampling switch S4 to open and the first sampling switch S1 to close; the controller is also configured to receive a second sampled voltage signal V2 after controlling the first sampling switch S1 to open and the second sampling switch S4 to close. Closing the first sampling switch S1 while the second sampling switch S4 is open improves the sampling accuracy of the first sampled voltage signal V1; closing the second sampling switch S4 while the first sampling switch S1 is open improves the sampling accuracy of the second sampled voltage signal V2.

[0041] In another embodiment of this application, the controller acquires a first detection voltage based on a first sampling voltage signal V1, and determines whether there is adhesion after the first contact pair S2 is cut off based on the first detection voltage; and the controller acquires a second detection voltage U3 based on a second sampling voltage signal V2, and determines whether there is adhesion after the second contact pair S3 is cut off based on the second detection voltage U3. Wherein, the first detection voltage U1 = V1*(R1+R2) / R1.

[0042] In some embodiments, the controller compares the first detection voltage U1 with the voltage U0 of the first voltage source V. If the difference between the first detection voltage U1 and the voltage U0 of the first voltage source V is within a preset threshold range, or if the first detection voltage U1 = U0, then it is determined that the first contact pair S2 is stuck together; otherwise, the first contact pair S2 is not stuck together.

[0043] In a further embodiment, since the interference voltage at the external load also changes at any time, in order to avoid judgment errors, the value of the first sampling voltage signal V1 can be collected multiple times at different times, and the first detection voltage U1 can be calculated multiple times. If the difference between the first detection voltage U1 and U0 is within the preset threshold range, it is determined that the first contact pair S2 is stuck; otherwise, it is determined that the first contact pair S2 is not stuck.

[0044] In some embodiments, the controller compares the second detection voltage U3 with the reference voltage provided by the second voltage source V3. If the difference between the second detection voltage U3 and V3 is within a preset threshold range, or if the second detection voltage U3 = V3, then it is determined that the second contact pair S3 has not stuck together; otherwise, the second contact pair S3 has stuck together.

[0045] In other embodiments, the controller compares the second detection voltage U3 with the calculated voltage value U4 of the second sampling point. If the difference between the second detection voltage U3 and U4 is within a preset threshold range, or if the second detection voltage U3 = U4, then it is determined that the second contact pair S3 has adhered; otherwise, the second contact pair S3 has not adhered. Wherein, U4 = V3 * R4 / (R3 + R4).

[0046] In a further embodiment, since the interference voltage at the external load also changes at any time, multiple data acquisitions and calculations can be performed at different times to avoid judgment errors.

[0047] This application detects a first sampling voltage signal V1 (i.e., the voltage division of the first sampling element R1) at the first sampling point by opening the second sampling switch S4 and closing the first sampling switch S1. A first detection voltage U1 is calculated from the first sampling voltage signal V1, and the first detection voltage U1 is used to determine whether the first contact pair S2 is stuck. Similarly, by opening the first sampling switch S1 and closing the second sampling switch S4, a second detection voltage U3 (the voltage division of the second sampling element R4) is obtained, and the second detection voltage U3 is used to determine whether the second contact pair S3 is stuck. In other words, the entire detection process only requires controlling the opening and closing of two sampling switches, without the need for auxiliary contacts or repeated opening and closing of other relays, to determine whether the relay under test is stuck. Therefore, using the solution of this application, the energy storage battery system does not require the use of relays with auxiliary contacts, reducing relay costs and improving detection reliability.

[0048] Another embodiment of this application discloses a battery management system, which includes the relay contact detection circuit of the above embodiment and a controller electrically connected to the relay contact detection circuit.

[0049] In a further embodiment, the battery management system also includes a load connected to the relay contact detection circuit. The load can be an inverter, a charging / discharging cabinet, etc. This embodiment does not specifically limit the load.

[0050] Based on the embodiments provided in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, some design, manufacturing, or production modifications based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0051] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0052] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms “a,” “an,” “an,” “the,” and similar words used in this application do not indicate quantity limitation and may indicate singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units not listed, or may include other steps or units inherent to these processes, methods, products, or devices. The terms “connected,” “linked,” “coupled,” and similar words used in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. “Multiple” used in this application means two or more. “And / or” describes the relationship between related objects, indicating that three relationships may exist; for example, “A and / or B” can represent: A alone, A and B simultaneously, and B alone. The terms “first,” “second,” “third,” etc., used in this application are merely to distinguish similar objects and do not represent a specific ordering of the objects.

[0053] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0054] The above embodiments merely illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A relay contact detection circuit, characterized by comprising: The relay contact detection circuit comprises a first detection circuit and a second detection circuit connected to each other, The first detection circuit comprises a first voltage source, a first contact pair, a first sampling switch and a first sampling unit connected in series, wherein the first contact pair is connected in series to a positive output terminal of the first voltage source; The second detection circuit comprises a second voltage source, a second sampling unit, a second sampling switch and a second contact pair connected in series, wherein the second contact pair is connected in series to a negative output terminal of the first voltage source, and a negative output terminal of the second voltage source is connected to the negative output terminal of the first voltage source; The first sampling unit is configured to obtain a first sampling voltage signal when the first sampling switch is closed, so as to determine whether there is adhesion after the first contact pair is cut off; The second sampling unit is configured to obtain a second sampling voltage signal when the second sampling switch is closed, so as to determine whether there is adhesion after the second contact pair is cut off.

2. The relay contact detection circuit of claim 1, wherein The first sampling unit comprises a first voltage dividing element and a first sampling element connected in series; the second sampling unit comprises a second voltage dividing element and a second sampling element connected in series; a sampling point of the first sampling voltage signal is a connection point of the first voltage dividing element and the first sampling element; and a sampling point of the second sampling voltage signal is a connection point of the second voltage dividing element and the second sampling element.

3. The relay contact detection circuit of claim 2, wherein, The first sampling switch and the second sampling switch are mechanical switches or electronic switches; and / or The first voltage dividing element and the second voltage dividing element are a voltage dividing resistor or a plurality of voltage dividing resistors connected in series; and / or The first sampling element and the second sampling element are a sampling resistor or a plurality of sampling resistors connected in series.

4. The relay contact detection circuit of claim 1, wherein, The negative output terminal of the first voltage source is grounded.

5. The relay contact detection circuit of claim 1, wherein, The first voltage source is a battery pack composed of a plurality of batteries connected in series.

6. The relay contact detection circuit of claim 1, wherein, The first contact pair and the second contact pair are redundant contact pairs.

7. A battery management system, characterized by, The battery management system comprises the relay contact detection circuit and a controller electrically connected to the relay contact detection circuit. The controller receives the first sampling voltage signal sent by the relay contact detection circuit after the first sampling switch is closed, and determines whether there is adhesion after the first contact pair is cut off according to the first sampling voltage signal. The controller receives the second sampling voltage signal sent by the relay contact detection circuit after the second sampling switch is closed, and determines whether there is adhesion after the second contact pair is cut off according to the second sampling voltage signal.

8. The battery management system according to claim 7, wherein The controller is configured to receive the first sampling voltage signal after the second sampling switch is turned off and the first sampling switch is turned on. The controller is further configured to receive the second sampling voltage signal after the first sampling switch is turned off and the second sampling switch is turned on.

9. The battery management system according to claim 8, wherein The controller obtains a first detection voltage according to the first sampling voltage signal, and determines whether there is adhesion after the first contact pair is cut off according to the first detection voltage; and The controller obtains a second detection voltage according to the second sampling voltage signal, and determines whether there is adhesion after the second contact pair is cut off according to the second detection voltage. ​ The controller obtains a second detection voltage according to the second sampling voltage signal, and determines whether the second contact pair is stuck after being cut off according to the second detection voltage.

10. The battery management system of claim 9, wherein, The first voltage source is connected with a load, The first detection voltage is a voltage of a connection point between the load and the first contact pair; The second detection voltage is a voltage divided by the second voltage source through the second sampling unit.

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