A diagnostic circuit and method for a high voltage relay in a vehicle battery pack

Abstract

The application provides a diagnosis circuit and method of a high-voltage relay in a vehicle battery pack. In the vehicle battery pack, the positive and negative poles of a battery are connected to external devices of the battery pack through a main positive relay and a main negative relay respectively. The diagnosis circuit comprises: one end of the main negative relay close to the negative pole of the battery is grounded to form a ground reference point; the two ends of the main positive relay and the end of the main negative relay away from the negative pole of the battery are connected to the ground reference point through sampling resistors respectively; the circuit between the end of the main positive relay close to the positive pole of the battery and the end of the main negative relay away from the negative pole of the battery is connected through a first inclined pull resistor, and the resistance value of the first inclined pull resistor is in the order of megohm.

Description

Technical Field

[0001] This invention relates to the field of high-voltage circuits in vehicle battery packs, and more particularly to a diagnostic circuit and method for a high-voltage relay in a vehicle battery pack. Background Technology

[0002] The rapid popularization of electric vehicles has led to increasing public concern about the safety of vehicle battery packs. Diagnosing the high-voltage relays in electric vehicle battery packs is a crucial means of ensuring electrical safety. Only after diagnosis confirms that the corresponding high-voltage relays are functioning correctly can they be closed to output high-voltage electricity.

[0003] In existing technologies, the diagnostic principle for high-voltage relays in vehicle battery packs primarily relies on comparing the voltage difference between the relay's terminals to determine if it has become stuck. However, while this method is effective for the main positive and negative relays in the battery pack, it fails to accurately diagnose the main negative relay and charging negative relay, which are connected to the battery's negative terminal. Some solutions use the closing of the pre-charge relay to determine if the main negative relay is stuck, but this method becomes difficult to implement once the battery pack is removed from the vehicle environment. Furthermore, there is a lack of effective and targeted solutions for diagnosing charging negative relays, posing a potential safety hazard to electric vehicle battery packs.

[0004] In order to overcome the above-mentioned defects in the existing technology, there is an urgent need in the field for a diagnostic circuit and method for high-voltage relays in vehicle battery packs. This circuit is used for the diagnosis of high-voltage relays in electric vehicle battery packs and can accurately and effectively diagnose faults in all high-voltage relays in the battery pack, especially the main negative relay and the charging negative relay. It is highly reliable and low in cost, and effectively ensures the high-voltage power safety of electric vehicle battery packs. Summary of the Invention

[0005] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0006] To overcome the aforementioned deficiencies in the prior art, the present invention provides a diagnostic circuit for a high-voltage relay in a vehicle battery pack. In this vehicle battery pack, the positive and negative terminals of the battery are connected to external devices via a main positive relay and a main negative relay, respectively. The diagnostic circuit includes: a grounded end of the main negative relay near the negative terminal of the battery to form a grounding reference point; two ends of the main positive relay and the end of the main negative relay away from the negative terminal of the battery respectively connected to the grounding reference point via sampling resistors; a circuit with a first pull-up resistor connecting the end of the main positive relay near the positive terminal of the battery and the end of the main negative relay away from the negative terminal of the battery, the first pull-up resistor having a resistance on the order of megaohms; a first switch located near the grounding reference point in the circuit branch connected to the grounding reference point; and second and third switches located near the ends of the main positive relay and the main negative relay away from the negative terminal of the battery, respectively, in the remaining circuit branches with sampling resistors; and a fourth switch located near the end of the main negative relay in the circuit branch with the first pull-up resistor.

[0007] In one embodiment, preferably, the two busbars containing the main positive relay and the main negative relay are also connected to charging busbars, which are respectively connected to external charging equipment through the charging positive relay and the charging negative relay. The ends of the charging positive relay and the charging negative relay away from the battery are also connected to the ground reference point through sampling resistors. The diagnostic circuit further includes connecting the end of the main positive relay near the positive terminal of the battery and the end of the charging negative relay away from the negative terminal of the battery through a circuit with a second pull-up resistor, the resistance of which is on the order of megaohms.

[0008] In one embodiment, preferably, the circuit branch connecting the end of the positive charging relay away from the positive battery terminal and the end of the negative charging relay away from the negative battery terminal and having a sampling resistor has a fifth switch and a sixth switch respectively at the ends near the positive charging relay and the negative charging relay; and the circuit having a second pull-up resistor has a seventh switch at the end near the negative charging relay.

[0009] In one embodiment, preferably, the two busbars containing the main positive relay and the main negative relay are also connected to charging busbars, which are respectively connected to external charging equipment through the charging positive relay and the charging negative relay. The ends of the charging positive relay and the charging negative relay away from the battery are also connected to the ground reference point through sampling resistors. The diagnostic circuit further includes a circuit in which the ends of the charging positive relay and the charging negative relay away from the battery are connected through a circuit with a third pull-up resistor, the resistance of which is on the order of megaohms.

[0010] In one embodiment, preferably, the circuit branch connecting the end of the positive charging relay away from the positive terminal of the battery and the end of the negative charging relay away from the negative terminal of the battery, and having a sampling resistor, has a fifth switch and a sixth switch respectively at the two ends near the positive charging relay and the negative charging relay.

[0011] In one embodiment, optionally, the positive charging bus of the positive charging relay is connected to the end of the main positive relay near the positive terminal of the battery, and the negative charging bus of the negative charging relay is connected to the end of the main negative relay near the negative terminal of the battery.

[0012] In one embodiment, optionally, the positive charging bus of the positive charging relay is connected to the end of the main positive relay away from the positive terminal of the battery, and the negative charging bus of the negative charging relay is connected to the end of the main negative relay away from the negative terminal of the battery.

[0013] In one embodiment, preferably, a precharge branch consisting of a precharge relay and a precharge resistor is connected in parallel across the two ends of the main positive relay.

[0014] Another aspect of the present invention provides a diagnostic method for a high-voltage relay in a vehicle battery pack, employing a diagnostic circuit as described above. The diagnostic method includes: keeping the main positive relay and the main negative relay in an open state; closing the first switch, the second switch, the third switch, and the fourth switch; detecting the voltage difference between the end of the main negative relay furthest from the battery and the ground reference point using a sampling resistor; indicating that the main negative relay has no short-circuit fault if the voltage difference is greater than a first preset threshold; indicating that the main negative relay has a short-circuit fault if the voltage difference does not exceed a second preset threshold; closing the main positive relay and the main negative relay; again detecting the voltage difference between the end of the main negative relay furthest from the battery and the ground reference point using a sampling resistor; indicating that the main negative relay has no open-circuit fault if the voltage difference does not exceed the second preset threshold; indicating that the main negative relay has an open-circuit fault if the voltage difference is greater than the first preset threshold; and disconnecting the second switch, the third switch, and the fourth switch after the diagnostic is completed.

[0015] In one embodiment, preferably, the two busbars containing the main positive relay and the main negative relay are also connected to charging busbars. These two charging busbars are connected to external charging equipment via the charging positive relay and the charging negative relay, respectively. The ends of the charging positive relay and the charging negative relay furthest from the battery are also connected to the ground reference point via sampling resistors. The end of the main positive relay closest to the positive terminal of the battery and the end of the charging negative relay furthest from the negative terminal of the battery are connected via a circuit with a second pull-up resistor. The resistance of the second pull-up resistor is on the order of megaohms. The circuit branch connecting the ends of the charging positive relay furthest from the positive terminal of the battery and the ends of the charging negative relay furthest from the negative terminal of the battery, and equipped with sampling resistors, has a fifth switch and a sixth switch at the ends near the charging positive relay and the charging negative relay, respectively. The circuit with the second pull-up resistor has a seventh switch at the end near the charging negative relay. The diagnostic method also includes... The process includes: closing the first, second, third, fourth, sixth, and seventh switches; closing the main positive and main negative relays; keeping the charging positive and charging negative relays in an open state; detecting the voltage difference between the end of the charging negative relay furthest from the battery and the ground reference point using a sampling resistor; if the voltage difference is greater than a first preset threshold, the charging negative relay has no short-circuit fault; if the voltage difference does not exceed a second preset threshold, the charging negative relay has a short-circuit fault; closing the charging negative relay; and again detecting the voltage difference between the end of the charging negative relay furthest from the battery and the ground reference point using a sampling resistor; if the voltage difference is less than the second preset threshold, the charging negative relay has no open-circuit fault; if the voltage difference is greater than the first preset threshold, the charging negative relay has an open-circuit fault; and after the diagnosis is completed, disconnecting the sixth and seventh switches.

[0016] In one embodiment, preferably, the two busbars containing the main positive relay and the main negative relay are also connected to charging busbars. These two charging busbars are connected to external charging equipment via the charging positive relay and the charging negative relay, respectively. The ends of the charging positive relay and the charging negative relay furthest from the battery are also connected to the ground reference point via sampling resistors. The ends of the charging positive relay and the charging negative relay furthest from the battery are also connected via a circuit with a third pull-up resistor. The resistance of the third pull-up resistor is on the order of megaohms. The circuit branch connecting the ends of the charging positive relay furthest from the battery positive terminal and the charging negative relay furthest from the battery negative terminal, and equipped with sampling resistors, has a fifth switch and a sixth switch respectively near the ends of the charging positive relay and the charging negative relay. The diagnostic method further includes... The process involves: closing the main positive relay and the main negative relay, closing the first switch, the sixth switch, and the charging positive relay; detecting the voltage difference between the end of the charging negative relay furthest from the battery and the ground reference point using a sampling resistor; if the voltage difference is greater than the first preset threshold, the charging negative relay has no short circuit fault; if the voltage difference does not exceed the second preset threshold, the charging negative relay has a short circuit fault; closing the charging negative relay and detecting the voltage difference between the end of the charging negative relay furthest from the battery and the ground reference point again using a sampling resistor; if the voltage difference is less than the second preset threshold, the charging negative relay has no open circuit fault; if the voltage difference is greater than the first preset threshold, the charging negative relay has an open circuit fault; and after the diagnosis is completed, disconnecting the sixth switch.

[0017] In one embodiment, preferably, the first preset threshold is the voltage value at both ends of the battery pack, and the second preset threshold ranges from 0 to 5V. Attached Figure Description

[0018] The above-described features and advantages of the present invention will be better understood after reading the following detailed description of embodiments of the present disclosure in conjunction with the accompanying drawings. In the drawings, components are not necessarily drawn to scale, and components having similar related characteristics or features may have the same or similar reference numerals.

[0019] Figure 1 This is a schematic diagram of the circuit structure of a diagnostic circuit for a high-voltage relay in a vehicle battery pack, according to an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the circuit structure of a diagnostic circuit for a high-voltage relay in a vehicle battery pack, according to another embodiment of the present invention.

[0021] Figure 3 This is a circuit diagram illustrating the diagnostic circuit of a high-voltage relay in a vehicle battery pack according to yet another embodiment of the present invention; and

[0022] Figure 4 This is a schematic flowchart illustrating a diagnostic method for a high-voltage relay in a vehicle battery pack according to an embodiment of the present invention.

[0023] For clarity, a brief explanation of the reference numerals in the accompanying drawings is provided below:

[0024] 101 battery

[0025] 102 Main Positive Relay

[0026] 103 Main Negative Relay

[0027] 104 sampling resistor

[0028] 105 charging positive relay

[0029] 106 charging negative relay

[0030] 107 Precharge Relay

[0031] 108 precharge resistor

[0032] R grounding reference point Detailed Implementation

[0033] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention is presented in conjunction with preferred embodiments, this does not mean that the features of the invention are limited to these embodiments. On the contrary, the purpose of describing the invention in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of the present invention. To provide a thorough understanding of the invention, many specific details will be included in the following description. The invention may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of the invention, some specific details will be omitted in the description.

[0034] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] Furthermore, the terms "upper," "lower," "left," "right," "top," "bottom," "horizontal," and "vertical" used in the following description should be understood as the orientations shown in the relevant paragraphs and accompanying drawings. These relative terms are for illustrative purposes only and do not imply that the described apparatus must be manufactured or operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0036] It is understood that although terms such as "first," "second," and "third" may be used herein to describe various components, regions, layers, and / or parts, these components, regions, layers, and / or parts should not be limited by these terms, and these terms are only used to distinguish different components, regions, layers, and / or parts. Therefore, the first components, regions, layers, and / or parts discussed below may be referred to as second components, regions, layers, and / or parts without departing from some embodiments of the present invention.

[0037] To overcome the aforementioned deficiencies in the existing technology, this invention provides a diagnostic circuit and method for high-voltage relays in a vehicle battery pack. This method can accurately and effectively diagnose faults in all high-voltage relays within the battery pack, especially the main negative relay and the charging negative relay. It is highly reliable and inexpensive, effectively ensuring the high-voltage electrical safety of electric vehicle battery packs.

[0038] Figure 1 This is a schematic diagram of the circuit structure of a diagnostic circuit for a high-voltage relay in a vehicle battery pack, according to an embodiment of the present invention.

[0039] Please refer to Figure 1 The diagnostic circuit for the high-voltage relay in the vehicle battery pack provided by the present invention connects the positive and negative terminals of the battery 101 to external devices of the battery pack through the main positive relay 102 and the main negative relay 103, respectively.

[0040] like Figure 1 As shown, the diagnostic circuit includes: one end of the main negative relay 103 near the negative terminal of the battery 101 is grounded to form a grounding reference point R, and the two ends of the main positive relay 102 ( Figure 1 Points A and B in the diagram) and the end of the main negative relay 103 furthest from the negative terminal of the battery 101 ( Figure 1 Point C is connected to the grounding reference point R through sampling resistor 104.

[0041] Meanwhile, in the diagnostic circuit provided by this invention, the main positive relay 102 is positioned near the positive terminal of the battery 101 (i.e., Figure 1 Point A) is the end of the main negative relay 103 furthest from the negative terminal of the battery 101 (i.e., Figure 1The battery 101 and point C are connected by a circuit with a first pull-up resistor R1. The first pull-up resistor R1 is used to introduce the voltage of the positive terminal of the battery 101 to the end of the main negative relay 103 away from the battery 101. Preferably, the resistance of the first pull-up resistor R1 is on the order of megaohms, so that the first pull-up resistor R1 acts as a current-limiting resistor, allowing only the voltage at point C to be raised, while generating as little current as possible, thereby preventing additional consumption of the battery pack's power.

[0042] In addition, preferably, in the diagnostic circuit provided by the present invention, such as Figure 1 As shown, the circuit branch connected to the grounding reference point R has a first switch S1 near the grounding reference point R. The other circuit branches with sampling resistors 104 have a second switch S2 and a third switch S3 near the end of the main positive relay 102 away from the positive terminal of the battery 101 (point B) and the end of the main negative relay 103 away from the negative terminal of the battery 101 (point C), respectively. The circuit branch with the first pull-up resistor R1 has a fourth switch S4 near the end of the main negative relay 103. These switches are disconnected when relay diagnosis is not required to prevent the output of high voltage to consume battery power or affect electrical safety when not needed.

[0043] Figure 2 This is a schematic diagram of the diagnostic circuit of a high-voltage relay in a vehicle battery pack, according to another embodiment of the present invention.

[0044] Please refer to Figure 2 In one embodiment, preferably, in the high-voltage circuit of the vehicle battery pack provided by the present invention, the two busbars where the main positive relay 102 and the main negative relay 103 are located are respectively connected to charging busbars, and the two charging busbars are respectively connected to external charging equipment through charging positive relay 105 and charging negative relay 106.

[0045] It should be noted that the high-voltage circuit of the vehicle battery pack provided by this invention can be as follows: Figure 2 As shown, the positive charging bus of the positive charging relay 105 can be connected to the end of the main positive relay 102 near the positive terminal of the battery 101, and the negative charging bus of the negative charging relay 106 can be connected to the end of the main negative relay 103 near the negative terminal of the battery 101. Alternatively, it can be used as follows: Figure 3 As shown, the positive charging bus of the positive charging relay 105 can also be connected to the end of the main positive relay 102 away from the positive terminal of the battery, while the negative charging bus of the negative charging relay 106 is connected to the end of the main negative relay 103 away from the negative terminal of the battery 101.

[0046] Regardless of which connection method is used for the charging bus, in the high-voltage circuit of the vehicle battery pack provided by the present invention, the ends (points D and E) of the positive charging relay 105 and the negative charging relay 106 away from the battery 101 are also connected to the grounding reference point R through the sampling resistor 104.

[0047] exist Figure 2 In the illustrated embodiment, a wire is led out from a circuit connected to the ground reference point R. Points B, C, D, and E are each connected to this wire through their respective sampling resistors 104, thereby achieving connectivity with the ground reference point R. With this circuit setup, voltage sampling at specific points can be achieved through these sampling resistors 104, facilitating relay diagnostics.

[0048] Please continue to refer to this. Figure 2 The diagnostic circuit provided by this invention further includes: connecting the end of the main positive relay 102 near the positive terminal of the battery (point A) to the end of the charging negative relay 106 away from the negative terminal of the battery (point E) via a circuit equipped with a second pull-up resistor R2, thereby introducing the high voltage of the positive terminal of the battery 101 to the end of the charging negative relay 106 to facilitate diagnosis. Similar to the first pull-up resistor R1, the resistance value of the second pull-up resistor can also be on the order of megaohms.

[0049] In one embodiment, preferably, as shown below Figure 2 As shown, the circuit branch connecting the end of the positive charging relay 105 away from the battery positive terminal (point D) and the end of the negative charging relay 106 away from the battery negative terminal (point E), and equipped with a sampling resistor 104, has a fifth switch S5 and a sixth switch S6 at the two ends (points D and E) near the positive charging relay 105 and the negative charging relay 106, respectively; simultaneously, the circuit equipped with a second pull-up resistor R2 has a seventh switch S7 at the end near the negative charging relay 106. Similarly, these switches are also disconnected when diagnostics are not required, thereby preventing additional battery power consumption or the output of high voltage when not needed, which could affect electrical safety.

[0050] Figure 3 This is a schematic diagram of the circuit structure of a diagnostic circuit for a high-voltage relay in a vehicle battery pack, according to another embodiment of the present invention. Figure 3 The embodiment shows a connection method in which two charging buses are respectively connected to the end of the main positive relay 102 and the main negative relay 103 away from the battery.

[0051] In addition to the connection points of the charging bus mentioned above, compared to Figure 2 The illustrated embodiment, in Figure 3In the illustrated embodiment, preferably, the diagnostic circuit in the high-voltage circuit of the vehicle battery pack provided by the present invention may further include: the ends of the positive charging relay 105 and the negative charging relay 106 furthest from the battery (points D and E) are connected by a circuit with a third pull-up resistor R3. The resistance value of the third pull-up resistor R3 may also be on the order of megaohms. The third pull-up resistor R3 can introduce the high voltage at point D to point E when the positive charging relay 105 is closed, thereby facilitating the diagnosis of the negative charging relay 106 and simplifying the diagnostic operation steps. The specific diagnostic method will be elaborated in the method section below.

[0052] Please refer to the following: Figures 1-3 In the high-voltage circuit of the vehicle battery pack provided by the present invention, a pre-charge branch consisting of a pre-charge relay 107 and a pre-charge resistor 108 can be connected in parallel across the two ends of the main positive relay 102 to perform the pre-charge function of the vehicle battery pack. When diagnosing the high-voltage relay of the vehicle battery pack, the pre-charge relay 107 and the main positive relay 102 maintain the same state and thus perform opening and closing operations simultaneously.

[0053] As can be seen from the above embodiments, in the diagnostic circuit of the high-voltage relay in the vehicle battery pack provided by the present invention, the high voltage at a specific point is introduced into the end of the main negative relay or the charging negative relay by setting the diagonal pull resistor, which solves the problem that the main negative relay and the charging negative relay are difficult to diagnose in the prior art. It realizes comprehensive and accurate diagnosis of battery pack relays, and only sets a grounding reference point R at the negative terminal of the battery, which saves device costs and facilitates the promotion and application of the diagnostic circuit.

[0054] Another aspect of the present invention provides a diagnostic method for a high-voltage relay in a vehicle battery pack, the diagnostic method employing, as follows: Figure 1 The diagnostic circuit shown can be used in conjunction with the reference. Figure 4 .

[0055] Figure 4 This is a schematic flowchart illustrating a diagnostic method for a high-voltage relay in a vehicle battery pack according to an embodiment of the present invention.

[0056] Please refer to the reference. Figure 1 and Figure 4 ,exist Figure 1 Performed in the diagnostic circuit shown Figure 4 The diagnostic method 400 shown may specifically include:

[0057] Step 401: Keep the main positive relay 102 and the main negative relay 103 in the open state, close the first switch S1, the second switch S2, the third switch S3 and the fourth switch S4, and detect the end of the main negative relay 103 furthest from the battery (i.e., the end of the main negative relay 103 furthest from the battery) through the sampling resistor 104 connected to the main negative relay 103. Figure 1 The voltage difference between point C and the grounding reference point R;

[0058] Then, step 402 is executed: in response to the voltage difference being greater than the first preset threshold, the main negative relay 103 has no short circuit fault;

[0059] Parallel to step 402, or step 403 is performed: in response to the voltage difference not exceeding the second preset threshold, the main negative relay 103 has a short circuit fault.

[0060] Next, step 404 is executed: the main positive relay 102 and the main negative relay 103 are closed, and the end of the main negative relay 103 furthest from the battery (i.e., the end connected to the battery) is detected again through the sampling resistor 104 connected to the main negative relay 103. Figure 1 The voltage difference between point C and the grounding reference point R;

[0061] Accordingly, steps 405 and 406 are executed in parallel. Step 405: In response to the voltage difference not exceeding the second preset threshold, the main negative relay has no open circuit fault.

[0062] Step 406: In response to the voltage difference being greater than the first preset threshold, the main negative relay has an open circuit fault;

[0063] Finally, step 407 is executed: After the diagnosis is completed, the second switch S2, the third switch S3 and the fourth switch S4 are disconnected to prevent additional battery power consumption or unwanted high-voltage discharge.

[0064] In one embodiment, preferably, the first preset threshold is the voltage value at both ends of the battery pack, and the second preset threshold ranges from 0 to 5V.

[0065] As will be readily understood by those skilled in the art, in the diagnostic circuit of the high-voltage relay for the vehicle battery pack provided by the present invention, by setting up the circuit and switches and using the above method, the voltage across the main and negative relays can be compared with the magnitude of two preset threshold voltages, thereby achieving a more accurate diagnostic operation of the main and negative relays. At the same time, only one grounding reference point R is set in the circuit, ensuring reliability and safety while also saving device costs.

[0066] Meanwhile, the diagnostic work for relays other than the main negative relay and the charging negative relay is similar and simple, so it will not be elaborated on in this article.

[0067] And for Figure 2 The diagnostic circuit shown, in one embodiment, the diagnostic method for the high-voltage relay of the vehicle battery pack provided by the present invention may further include:

[0068] Close the first switch S1, the second switch S2, the third switch S3, the fourth switch S4, the sixth switch S6, and the seventh switch S7; close the main positive relay 102 and the main negative relay 103; keep the charging positive relay 105 and the charging negative relay 106 in the open state; and detect the end of the charging negative relay 106 furthest from the battery through the sampling resistor 104 connected to the charging negative relay 106. Figure 2 The voltage difference between point E and the grounding reference point R;

[0069] If the voltage difference is greater than the first preset threshold, the charging negative relay 106 has no short circuit fault; if the voltage difference is less than the second preset threshold, the charging negative relay 106 has a short circuit fault.

[0070] Next, the negative charging relay 106 is closed again, and the end of the negative charging relay 106 furthest from the battery is detected again through the sampling resistor. Figure 2 The voltage difference between point E and the grounding reference point R;

[0071] If the voltage difference is less than the second preset threshold, the charging negative relay 106 has no open circuit fault; if the voltage difference is greater than the first preset threshold, the charging negative relay 106 has an open circuit fault.

[0072] Finally, after the diagnosis is completed, disconnect the sixth switch S6 and the seventh switch S7.

[0073] In another embodiment, for example, for Figure 3 The diagnostic circuit shown in the invention, and the diagnostic method for the high-voltage relay of the vehicle battery pack provided by this invention, may further include:

[0074] First, close the main positive relay 102 and the main negative relay 103, close the first switch S1, the sixth switch S6, and the charging positive relay 105, and detect the end of the charging negative relay 106 furthest from the battery through the sampling resistor 104 connected to the charging negative relay 106. Figure 3 The voltage difference between point E and the grounding reference point R;

[0075] If the voltage difference is greater than the first preset threshold, the charging negative relay 106 has no short circuit fault; if the voltage difference is less than the second preset threshold, the charging negative relay 106 has a short circuit fault.

[0076] Next, the charging negative relay 106 is closed, and the voltage difference between the end of the charging negative relay 106 furthest from the battery (point E) and the ground reference point R is detected again through the sampling resistor.

[0077] If the voltage difference is less than the second preset threshold, the charging negative relay 106 has no open circuit fault; if the voltage difference is greater than the first preset threshold, the charging negative relay 106 has an open circuit fault.

[0078] After the final diagnosis is completed, disconnect the sixth switch S6.

[0079] As can be seen from this embodiment, the third pull-up resistor R3 provides another possible method for diagnosing the charging negative relay 106.

[0080] It should be noted that, in the above embodiments, preferably, the first preset threshold can be the voltage value at both ends of the battery pack, and the value range of the second preset threshold can be 0 to 5V. Simultaneously, the pre-charge relay 107 and the main positive relay 102 are synchronously controlled to maintain the same opening and closing state.

[0081] Although the methods described above are illustrated and depicted as a series of actions for the sake of simplicity, it should be understood and appreciated that these methods are not limited by the order of the actions, as some actions may occur in a different order and / or concurrently with other actions from the illustrations and descriptions herein or not illustrated and described herein but which may be understood by those skilled in the art, according to one or more embodiments.

[0082] The diagnostic circuit and method for high-voltage relays in vehicle battery packs provided by this invention, through the ingenious design of sampling resistors, pull-up resistors and corresponding circuits, can accurately and effectively diagnose faults in all high-voltage relays in the battery pack, especially the main negative relay and the charging negative relay. It has high reliability. At the same time, since only one grounding reference point R is set in the circuit, the device cost of the circuit is reduced, effectively ensuring the high-voltage power safety of electric vehicle battery packs and facilitating widespread application.

[0083] The prior description of this disclosure is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to this disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not intended to be limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A diagnostic circuit for a high-voltage relay in a vehicle battery pack, wherein the positive and negative terminals of the battery in the vehicle battery pack are respectively connected to external devices of the battery pack via a main positive relay and a main negative relay, the diagnostic circuit comprising: The end of the main negative relay closest to the negative terminal of the battery is grounded to form a grounding reference point. The two ends of the main positive relay and the end of the main negative relay furthest from the negative terminal of the battery are respectively connected to the grounding reference point through a sampling resistor. The end of the main positive relay near the positive terminal of the battery is connected to the end of the main negative relay away from the negative terminal of the battery through a circuit with a first inclined pull resistor, the resistance of which is on the order of megaohms. The circuit branch connected to the grounding reference point has a first switch near the grounding reference point. The other circuit branches with sampling resistors have a second switch and a third switch near the end of the main positive relay away from the positive terminal of the battery and the end of the main negative relay away from the negative terminal of the battery, respectively. The circuit branch equipped with the first inclined pull resistor has a fourth switch at the end near the main negative relay.

2. The diagnostic circuit as described in claim 1, characterized in that, The main positive relay and the main negative relay are respectively connected to charging busbars. These two charging busbars are connected to external charging equipment through the charging positive relay and the charging negative relay, respectively. The ends of the charging positive relay and the charging negative relay furthest from the battery are also connected to the ground reference point through sampling resistors. The diagnostic circuit also includes: The end of the main positive relay near the positive terminal of the battery is connected to the end of the charging negative relay away from the negative terminal of the battery through a circuit with a second pull resistor, the resistance of which is on the order of megaohms.

3. The diagnostic circuit as described in claim 2, characterized in that, A circuit branch connecting the end of the positive charging relay furthest from the battery positive terminal and the end of the negative charging relay furthest from the battery negative terminal, and equipped with a sampling resistor, has a fifth switch and a sixth switch respectively located at the ends near the positive and negative charging relays; and The circuit equipped with a second pull resistor has a seventh switch at one end near the negative charging relay.

4. The diagnostic circuit as described in claim 1, characterized in that, The main positive relay and the main negative relay are respectively connected to charging busbars. These two charging busbars are connected to external charging equipment through the charging positive relay and the charging negative relay, respectively. The ends of the charging positive relay and the charging negative relay furthest from the battery are also connected to the ground reference point through sampling resistors. The diagnostic circuit also includes: The positive charging relay and the negative charging relay are connected by a circuit with a third inclined pull resistor, the resistance of which is on the order of megaohms.

5. The diagnostic circuit as described in claim 4, characterized in that, A circuit branch connecting the end of the positive charging relay away from the positive terminal of the battery and the end of the negative charging relay away from the negative terminal of the battery, and equipped with a sampling resistor, has a fifth switch and a sixth switch respectively at the two ends near the positive charging relay and the negative charging relay.

6. The diagnostic circuit as described in any one of claims 2 or 4, characterized in that, The positive charging bus of the positive charging relay is connected to the end of the main positive relay near the positive terminal of the battery, and the negative charging bus of the negative charging relay is connected to the end of the main negative relay near the negative terminal of the battery.

7. The diagnostic circuit as described in any one of claims 2 or 4, characterized in that, The charging positive busbar of the charging positive relay is connected to the end of the main positive relay away from the positive terminal of the battery, and the charging negative busbar of the charging negative relay is connected to the end of the main negative relay away from the negative terminal of the battery.

8. The diagnostic circuit as described in claim 1, characterized in that, A precharge branch consisting of a precharge relay and a precharge resistor is connected in parallel across the two ends of the main positive relay.

9. A diagnostic method for a high-voltage relay in a vehicle battery pack, employing the diagnostic circuit as described in claim 1, the diagnostic method comprising: Keep the main positive relay and the main negative relay in the open state, close the first switch, the second switch, the third switch and the fourth switch, and detect the voltage difference between the end of the main negative relay away from the battery and the ground reference point through the sampling resistor; If the voltage difference is greater than a first preset threshold, then the main negative relay has no short-circuit fault; If the voltage difference does not exceed a second preset threshold, then the main negative relay has a short circuit fault. Close the main positive relay and the main negative relay, and again detect the voltage difference between the end of the main negative relay furthest from the battery and the ground reference point through the sampling resistor; If the voltage difference does not exceed the second preset threshold, then the main negative relay has no open circuit fault. If the voltage difference is greater than the first preset threshold, then the main negative relay has an open circuit fault. as well as After the diagnosis is completed, disconnect the second switch, the third switch, and the fourth switch.

10. The diagnostic method as described in claim 9, characterized in that, The main positive relay and the main negative relay are connected to two charging busbars, which are respectively connected to external charging equipment through the charging positive relay and the charging negative relay. The ends of the charging positive relay and the charging negative relay away from the battery are also connected to the ground reference point through sampling resistors. The end of the main positive relay near the positive terminal of the battery and the end of the charging negative relay away from the negative terminal of the battery are connected by a circuit with a second inclined pull resistor. The resistance of the second inclined pull resistor is on the order of megaohms. The circuit branch connecting the end of the charging positive relay away from the positive terminal of the battery and the end of the charging negative relay away from the negative terminal of the battery, and equipped with a sampling resistor, has a fifth switch and a sixth switch at the two ends near the charging positive relay and the charging negative relay, respectively. The circuit with the second pull-up resistor has a seventh switch at one end near the negative charging relay, and the diagnostic method further includes: Close the first switch, the second switch, the third switch, the fourth switch, the sixth switch, and the seventh switch; close the main positive relay and the main negative relay; keep the charging positive relay and the charging negative relay in the open state; and detect the voltage difference between the end of the charging negative relay furthest from the battery and the ground reference point through the sampling resistor. If the voltage difference is greater than the first preset threshold, then the charging negative relay has no short circuit fault. If the voltage difference does not exceed the second preset threshold, then the charging negative relay has a short circuit fault; Close the charging negative relay and detect the voltage difference between the end of the charging negative relay furthest from the battery and the ground reference point again through the sampling resistor; If the voltage difference is less than the second preset threshold, then the charging negative relay has no open circuit fault. If the voltage difference exceeds the first preset threshold, then the charging negative relay has an open circuit fault; and After the diagnosis is completed, disconnect the sixth switch and the seventh switch.

11. The diagnostic method as described in claim 9, characterized in that, The main positive relay and the main negative relay are connected to two charging busbars, which are respectively connected to external charging equipment through the charging positive relay and the charging negative relay. The ends of the charging positive relay and the charging negative relay furthest from the battery are also connected to the ground reference point through sampling resistors. The ends of the charging positive relay and the charging negative relay furthest from the battery are also connected by a circuit with a third inclined pull resistor. The resistance of the third inclined pull resistor is on the order of megaohms. The circuit branch connecting the ends of the charging positive relay furthest from the battery positive terminal and the ends of the charging negative relay furthest from the battery negative terminal, and equipped with sampling resistors, has a fifth switch and a sixth switch respectively near the ends of the charging positive relay and the charging negative relay. The diagnostic method further includes: Close the main positive relay and the main negative relay, close the first switch, the sixth switch and the charging positive relay, and detect the voltage difference between the end of the charging negative relay away from the battery and the ground reference point through the sampling resistor; If the voltage difference is greater than the first preset threshold, then the charging negative relay has no short circuit fault. If the voltage difference does not exceed the second preset threshold, then the charging negative relay has a short circuit fault; Close the charging negative relay and detect the voltage difference between the end of the charging negative relay furthest from the battery and the ground reference point again through the sampling resistor; If the voltage difference is less than the second preset threshold, then the charging negative relay has no open circuit fault. If the voltage difference exceeds the first preset threshold, then the charging negative relay has an open circuit fault; and After the diagnosis is completed, disconnect the sixth switch.

12. The diagnostic method according to any one of claims 9 to 11, characterized in that, The first preset threshold is the voltage value at both ends of the battery pack, and the second preset threshold ranges from 0 to 5V.

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