A relay sticking detection circuit and system

Abstract

The application provides a relay sticking detection circuit and system, and relates to the technical field of relays.The first ends of the first detection module and the second detection module in the circuit are connected with the input ends of the positive bus relay and the negative bus relay respectively, the second end of the first detection module is connected with the output end of the positive bus relay and the input end of the negative bus relay respectively, and the second end of the second detection module is connected with the output end of the negative bus relay and the input end of the positive bus relay respectively.The output end of the first detection module outputs the first level when the positive bus relay has a sticking fault, and outputs the second level when the positive bus relay does not have a sticking fault.The output end of the second detection module outputs the first level when the negative bus relay has a sticking fault, and outputs the second level when the negative bus relay does not have a sticking fault.The relay sticking detection circuit realizes the sticking detection function of the non-feedback contact relay, and reduces the cost.

Description

Technical Field

[0001] This application relates to the field of relay technology, and more specifically, to a relay adhesion detection circuit and system. Background Technology

[0002] In the high-voltage boxes of energy storage products, the PCS (Power Conversion System), and the high-voltage power-on control circuits of electric vehicles, both the positive and negative DC busbars are equipped with relay switching circuits. Because the positive and negative busbar relays need to handle large operating currents during abnormal shutdowns, their contacts may stick together. In such cases, the system must be able to detect and identify this sticking in a timely manner to facilitate subsequent protection actions.

[0003] Existing detection methods use relays with feedback contacts to detect contact status. These relays use internal mechanical structures (such as auxiliary contacts) to provide feedback on the actual on / off state of the main contacts, thereby determining whether a sticking fault exists. However, this design relies on complex mechanical linkage mechanisms, resulting in a large overall relay size and high manufacturing costs. In other words, existing relays with feedback contacts are not suitable for applications requiring high space utilization and low cost. Utility Model Content

[0004] The purpose of this application is to provide a relay adhesion detection circuit and system to reduce costs while achieving relay adhesion detection.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0006] On the one hand, this application provides a relay adhesion detection circuit, including: a positive bus relay, a negative bus relay, a first detection module and a second detection module;

[0007] The input and output terminals of the positive bus relay are respectively connected to the positive terminal of the battery and one end of the bus capacitor, and the input and output terminals of the negative bus relay are respectively connected to the negative terminal of the battery and the other end of the bus capacitor.

[0008] The first terminal of the first detection module is connected to the input terminal of the positive bus relay, and the second terminal of the first detection module is connected to the output terminal of the positive bus relay and the input terminal of the negative bus relay, respectively; the first terminal of the second detection module is connected to the input terminal of the negative bus relay, and the second terminal of the second detection module is connected to the output terminal of the negative bus relay and the input terminal of the positive bus relay, respectively.

[0009] The output terminal of the first detection module is used to output a first level when the positive bus relay has a sticking fault, and to output a second level when the positive bus relay does not have a sticking fault;

[0010] The output terminal of the second detection module is used to output a first level when the negative bus relay has a sticking fault, and to output a second level when the negative bus relay does not have a sticking fault.

[0011] Furthermore, the relay adhesion detection circuit also includes a first resistor, and the first detection module includes a first optocoupler, a first diode, and a second resistor;

[0012] The anode of the first diode is connected to the input terminal of the positive bus relay, and the cathode of the first diode is connected to the anode of the first optocoupler. The cathode of the first optocoupler is connected to the output terminal of the positive bus relay and one end of the first resistor, while the other end of the first resistor is connected to the input terminal of the negative bus relay. The emitter of the first optocoupler is grounded, and the collector of the first optocoupler is connected to one end of the second resistor, while the other end of the second resistor is connected to the power supply. The collector of the first optocoupler serves as the output terminal of the first detection module.

[0013] When the positive bus relay experiences a sticking fault, the first optocoupler is cut off, and the collector of the first optocoupler outputs a high level.

[0014] When the positive bus relay does not experience a sticking fault, the first optocoupler is turned on, and the collector of the first optocoupler outputs a low level.

[0015] Furthermore, the first detection module also includes a second diode; the anode of the second diode is connected to the cathode of the first optocoupler, and the cathode of the second diode is connected to the anode of the first optocoupler.

[0016] Furthermore, the first detection module also includes a third resistor; one end of the third resistor is connected to the cathode of the first optocoupler, and the other end of the third resistor is connected to the output terminal of the positive bus relay and one end of the first resistor, respectively.

[0017] Furthermore, the relay adhesion detection circuit also includes a fourth resistor, and the second detection module includes a second optocoupler, a third diode, and a fifth resistor;

[0018] The cathode of the second optocoupler is connected to the input terminal of the negative bus relay, and the anode of the second optocoupler is connected to the cathode of the third diode. The anode of the third diode is connected to the output terminal of the negative bus relay and one end of the fourth resistor, respectively. The other end of the fourth resistor is connected to the input terminal of the positive bus relay. The emitter of the second optocoupler is grounded, and the collector of the second optocoupler is connected to one end of the fifth resistor. The other end of the fifth resistor is connected to the power supply. The collector of the second optocoupler serves as the output terminal of the second detection module.

[0019] When the negative bus relay experiences a sticking fault, the second optocoupler is cut off, and the collector of the second optocoupler outputs a high level.

[0020] When the negative bus relay does not experience a sticking fault, the second optocoupler is turned on, and the collector of the second optocoupler outputs a low level.

[0021] Furthermore, the second detection module also includes a fourth diode; the anode of the fourth diode is connected to the cathode of the second optocoupler, and the cathode of the fourth diode is connected to the anode of the second optocoupler.

[0022] Furthermore, the second detection module also includes a sixth resistor; one end of the sixth resistor is connected to the cathode of the second optocoupler, and the other end of the sixth resistor is connected to the input terminal of the negative bus relay.

[0023] Furthermore, the relay adhesion detection circuit also includes a control detection module; the first input terminal of the control detection module is connected to the output terminal of the first detection module, and the second input terminal of the control detection module is connected to the output terminal of the second detection module;

[0024] The control detection module is used to determine the adhesion state of the positive bus relay based on the level signal output by the first detection module, and to determine the adhesion state of the negative bus relay based on the level signal output by the second detection module.

[0025] On the other hand, this application also provides a relay sticking detection system, including: a battery, a bus capacitor, and a relay sticking detection circuit as described in any of the foregoing embodiments.

[0026] Furthermore, the relay adhesion detection system also includes: a positive busbar pre-charge relay, a negative busbar pre-charge relay, a positive busbar pre-charge resistor, and a negative busbar pre-charge resistor;

[0027] One end of the positive bus precharge relay is connected to the positive terminal of the battery, and the other end of the positive bus precharge relay is connected to one end of the bus capacitor through the positive bus precharge resistor.

[0028] One end of the negative bus precharge relay is connected to the negative terminal of the battery, and the other end of the negative bus precharge relay is connected to the other end of the bus capacitor through the negative bus precharge resistor.

[0029] Compared with the prior art, this application has the following advantages:

[0030] This application provides a relay sticking detection circuit and system. The circuit includes: a positive bus relay, a negative bus relay, a first detection module, and a second detection module. The input and output terminals of the positive bus relay are connected to the positive terminal of a battery and one end of a bus capacitor, respectively. The input and output terminals of the negative bus relay are connected to the negative terminal of the battery and the other end of the bus capacitor, respectively. The first terminal of the first detection module is connected to the input terminal of the positive bus relay, and the second terminal of the first detection module is connected to both the output terminal of the positive bus relay and the input terminal of the negative bus relay. The first terminal of the second detection module is connected to the input terminal of the negative bus relay, and the second terminal of the second detection module is connected to both the output terminal of the negative bus relay and the input terminal of the positive bus relay. The output terminal of the first detection module outputs a first level when a sticking fault occurs in the positive bus relay, and outputs a second level when no sticking fault occurs in the positive bus relay. The output terminal of the second detection module outputs a first level when a sticking fault occurs in the negative bus relay, and outputs a second level when no sticking fault occurs in the negative bus relay.

[0031] Compared to the feedback-contact relays used in existing technologies, the positive and negative bus relays in this embodiment are ordinary relays without feedback contacts. The level signal output by the first detection module can effectively detect the sticking state of the positive bus relay, and the level signal output by the second detection module can effectively detect the sticking state of the negative bus relay, thus realizing the sticking detection function of the feedback-free contact relay. The relay sticking detection circuit provided in this embodiment has a simple structure, requiring no complex mechanical structure design, reducing the overall system size and cost, and expanding the application range of low-cost feedback-free contact relays. Attached Figure Description

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, 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. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0033] Figure 1 One of the circuit diagrams of a relay adhesion detection circuit provided in the embodiments of this application;

[0034] Figure 2 A second circuit diagram of a relay adhesion detection circuit provided in an embodiment of this application;

[0035] Figure 3 A third circuit diagram of a relay adhesion detection circuit provided in an embodiment of this application;

[0036] Figure 4 The fourth circuit diagram of a relay adhesion detection circuit provided in the embodiments of this application;

[0037] Figure 5 This is one of the schematic diagrams of a relay adhesion detection circuit provided in an embodiment of this application;

[0038] Figure 6 A schematic diagram of a relay adhesion detection circuit provided in an embodiment of this application;

[0039] Figure 7 This is a circuit diagram of a relay adhesion detection system provided in an embodiment of this application.

[0040] Icons: 10 - Relay adhesion detection circuit; 11 - Positive bus relay; 12 - Negative bus relay; 13 - First detection module; 14 - Second detection module; OC1 - First optocoupler; OC2 - Second optocoupler; D1 - First diode; D2 - Second diode; D3 - Third diode; D4 - Fourth diode; R1 - First resistor; R2 - Second resistor; R3 - Third resistor; R4 - Fourth resistor; R5 - Fifth resistor; R6 - Sixth resistor; 100 - Relay adhesion detection system; 20 - Battery; 30 - Bus capacitor; 40 - Positive bus pre-charge relay; 50 - Negative bus pre-charge relay; R7 - Positive bus pre-charge resistor; R8 - Negative bus pre-charge resistor. Detailed Implementation

[0041] 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 a part of the embodiments of this application, and not all of the embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0042] In the description of this application, it should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The term "connection" should be interpreted broadly, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0043] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0044] As described in the background section, in abnormal shutdown situations, the system needs to quickly disconnect the positive and negative bus relays to meet response speed requirements. At this time, because the positive and negative bus relays are in a load-switching state, the high-voltage, high-current shutdown can easily cause arcing, leading to erosion and aging of the contact plating. Over time, this can result in the relay contacts sticking together. Although the power circuit can be cut off through system control, if this sticking condition is not detected in time, the surge current will impact the bus capacitor upon the next power-on, causing significant damage to the system. Therefore, detecting the sticking condition of the positive and negative bus relays is particularly important.

[0045] Existing technology uses relays with feedback contacts to detect contact status. However, this type of relay has a complex internal structure, resulting in a large size and high manufacturing cost, making it unsuitable for space-constrained or cost-sensitive applications.

[0046] In view of this, this application selects a relay solution without feedback contacts. In this case, a relay adhesion detection circuit is needed to identify the contact state to achieve the purpose of system protection. To support the needs of this application, improve the overall power density, and save costs, this application provides a relay adhesion detection circuit for DC bus to realize the adhesion detection function of the feedbackless contact relay, thereby reducing the cost of system circuit design and expanding the application scope of low-cost feedbackless contact relays.

[0047] Specifically, please refer to Figure 1 This application provides a relay adhesion detection circuit 10, which includes: a positive bus relay 11, a negative bus relay 12, a first detection module 13, and a second detection module 14.

[0048] The input and output terminals of the positive bus relay 11 are connected to the positive terminal (BAT+) of the battery 20 and one end (BUS+) of the bus capacitor 30, respectively, while the input and output terminals of the negative bus relay 12 are connected to the negative terminal (BAT-) of the battery 20 and the other end (BUS-) of the bus capacitor 30, respectively.

[0049] The first terminal of the first detection module 13 is connected to the input terminal of the positive bus relay 11, and the second terminal of the first detection module 13 is connected to the output terminal of the positive bus relay 11 and the input terminal of the negative bus relay 12, respectively. The first terminal of the second detection module 14 is connected to the input terminal of the negative bus relay 12, and the second terminal of the second detection module 14 is connected to the output terminal of the negative bus relay 12 and the input terminal of the positive bus relay 11, respectively.

[0050] The output terminal of the first detection module 13 is used to output a first level when the positive bus relay 11 has a sticking fault, and to output a second level when the positive bus relay 11 does not have a sticking fault.

[0051] The output terminal of the second detection module 14 is used to output a first level when the negative bus relay 12 has a sticking fault, and to output a second level when the negative bus relay 12 does not have a sticking fault.

[0052] Compared to the feedback contact relays used in existing technologies, the positive bus relay 11 and negative bus relay 12 in this embodiment are both ordinary relays without feedback contacts. The level signal output by the first detection module 13 can effectively detect the sticking state of the positive bus relay 11, and the level signal output by the second detection module 14 can effectively detect the sticking state of the negative bus relay 12, thus realizing the sticking detection function of the feedbackless contact relay. The relay sticking detection circuit 10 provided in this embodiment has a simple structure, does not require complex mechanical linkage design, reduces the size and cost of the entire system, and expands the application range of low-cost feedbackless contact relays.

[0053] Furthermore, in this embodiment, the relay adhesion detection circuit 10 further includes a control detection module (not shown in the figure). The first input terminal of the control detection module is connected to the output terminal of the first detection module 13, and the second input terminal of the control detection module is connected to the output terminal of the second detection module 14.

[0054] The control detection module is used to determine the sticking state of the positive bus relay 11 based on the level signal output by the first detection module 13, and to determine the sticking state of the negative bus relay 12 based on the level signal output by the second detection module 14.

[0055] For a better understanding, please refer to Figure 2 In one optional embodiment, the relay adhesion detection circuit 10 further includes a first resistor R1, and the first detection module 13 includes a first optocoupler OC1, a first diode D1, and a second resistor R2.

[0056] The anode of the first diode D1 is connected to the input terminal of the positive bus relay 11, and the cathode of the first diode D1 is connected to the anode of the first optocoupler OC1. The cathode of the first optocoupler OC1 is connected to both the output terminal of the positive bus relay 11 and one end of the first resistor R1. The other end of the first resistor R1 is connected to the input terminal of the negative bus relay 12. Furthermore, the emitter of the first optocoupler OC1 is grounded, and the collector of the first optocoupler OC1 is connected to one end of the second resistor R2. The other end of the second resistor R2 is connected to the power supply VCC. The collector of the first optocoupler OC1 serves as the output terminal of the first detection module 13.

[0057] When the positive bus relay 11 experiences a sticking fault, the first optocoupler OC1 is cut off, and the collector of the first optocoupler OC1 outputs a high level (i.e., the first level).

[0058] When the positive bus relay 11 does not experience a sticking fault, the first optocoupler OC1 is turned on, and the collector of the first optocoupler OC1 outputs a low level (i.e., the second level).

[0059] Based on the above design, in the event of an abnormal shutdown, if the positive bus relay 11 becomes stuck, the first optocoupler OC1 will be short-circuited (i.e., the first optocoupler OC1 will be cut off). At this time, no current flows through the first optocoupler OC1, and the signal at the collector of the first optocoupler OC1 will be pulled high to the high level VCC by the second resistor R2 (i.e., the collector of the first optocoupler OC1 will output a high level). The control detection module can detect the sticking fault of the positive bus relay 11 through this high-level signal.

[0060] Correspondingly, if the positive bus relay 11 is not stuck (i.e., the positive bus relay 11 is open), the current flows out from the positive terminal of the battery 20, through the first diode D1, the first optocoupler OC1 and the first resistor R1 back to the negative terminal of the battery 20. At this time, the first optocoupler OC1 is effectively driven (i.e., the first optocoupler OC1 is turned on), and the signal at the collector of the first optocoupler OC1 is pulled down to ground GND (i.e., the collector of the first optocoupler OC1 outputs a low level). The control detection module can detect that the positive bus relay 11 has not experienced a sticking fault through this low-level signal.

[0061] In another alternative embodiment, the relay adhesion detection circuit 10 further includes a fourth resistor R4, and the second detection module 14 includes a second optocoupler OC2, a third diode D3, and a fifth resistor R5.

[0062] The cathode of the second optocoupler OC2 is connected to the input terminal of the negative bus relay 12, and the anode of the second optocoupler OC2 is connected to the cathode of the third diode D3. The anode of the third diode D3 is connected to both the output terminal of the negative bus relay 12 and one end of the fourth resistor R4. The other end of the fourth resistor R4 is connected to the input terminal of the positive bus relay 11. Furthermore, the emitter of the second optocoupler OC2 is grounded, and the collector of the second optocoupler OC2 is connected to one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to the power supply VCC. The collector of the second optocoupler OC2 serves as the output terminal of the second detection module 14.

[0063] When the negative bus relay 12 experiences a sticking fault, the second optocoupler OC2 is cut off, and the collector of the second optocoupler OC2 outputs a high level (i.e., the first level).

[0064] When the negative bus relay 12 does not experience a sticking fault, the second optocoupler OC2 is turned on, and the collector of the second optocoupler OC2 outputs a low level (i.e., the second level).

[0065] Based on the above design, in the event of an abnormal shutdown, if the negative bus relay 12 sticks together, the second optocoupler OC2 will be short-circuited (i.e., the second optocoupler OC2 will be cut off). At this time, no current flows through the second optocoupler OC2, and the signal at the collector of the second optocoupler OC2 will be pulled high to the high level VCC by the fifth resistor R5 (i.e., the collector of the second optocoupler OC2 will output a high level). The control detection module can detect the sticking fault of the negative bus relay 12 through this high-level signal.

[0066] Correspondingly, if the negative bus relay 12 is not stuck (i.e., the negative bus relay 12 is open), the current flows out from the positive terminal of the battery 20, through the fourth resistor R4, the third diode D3, and the second optocoupler OC2 back to the negative terminal of the battery 20. At this time, the second optocoupler OC2 is effectively driven (i.e., the second optocoupler OC2 is turned on), and the signal at the collector of the second optocoupler OC2 is pulled down to ground GND (i.e., the collector of the second optocoupler OC2 outputs a low level). The control detection module can detect that the negative bus relay 12 has not experienced a sticking fault through this low-level signal.

[0067] It should be noted that, in this embodiment, the first diode D1 and the third diode D3 serve as rectifier diodes, providing unidirectional current to the first optocoupler OC1 and the second optocoupler OC2, respectively. Furthermore, the first resistor R1 can be formed by connecting multiple resistors in series, and the fourth resistor R4 can also be formed by connecting multiple resistors in series to meet voltage withstand requirements.

[0068] In this embodiment, the cathode of the first optocoupler OC1 is also connected to the input terminal of the negative bus relay 12 (i.e., the negative terminal of the battery 20) through a first resistor R1, and the anode of the third diode D3 is also connected to the input terminal of the positive bus relay 11 (i.e., the positive terminal of the battery 20) through a fourth resistor R4. The purpose is to ensure that when the positive bus relay 11 and / or the negative bus relay 12 are disconnected (i.e., when no sticking fault occurs), the corresponding optocoupler can be effectively driven to output a low level. The specific analysis is as follows:

[0069] Please see Figure 3Assuming the cathode of the first optocoupler OC1 is connected only to the output terminal of the positive bus relay 11, and the anode of the third diode D3 is connected only to the output terminal of the negative bus relay 12, then when the system power circuit is not started (i.e., the voltage difference between the bus capacitor 30 and the battery 20 is small), if the positive bus relay 11 and / or the negative bus relay 12 are disconnected, only a very small current will flow through the first optocoupler OC1 and / or the second optocoupler OC2. Since the CTR (Current Transfer Ratio) of the optocoupler is finite, the photodiode inside the optocoupler cannot effectively drive the internal transistor. That is, the first optocoupler OC1 and / or the second optocoupler OC2 will remain in the off state, outputting a high level. This will cause the control detection module to incorrectly detect the relay state as a stuck state.

[0070] To avoid the above situation, please refer to the following again. Figure 2 This application, by adding a first resistor R1 and a fourth resistor R4, ensures that even when the voltage of battery 20 and bus capacitor 30 are not significantly different, as long as the positive bus relay 11 and / or the negative bus relay 12 are disconnected, the current flowing through the first resistor R1 and / or the fourth resistor R4 will form a current loop through the first optocoupler OC1 and / or the second optocoupler OC2 respectively (this current loop does not pass through the bus capacitor 30), and finally return to the negative terminal of battery 20. At this time, the first optocoupler OC1 and / or the second optocoupler OC2 can be effectively driven, outputting a low level, and the control detection module can correctly detect that the positive bus relay 11 and / or the negative bus relay 12 have not experienced a sticking fault.

[0071] Furthermore, since the photodiode in the optocoupler has a weak reverse voltage tolerance, if a reverse voltage is unexpectedly generated in the circuit, it may cause the photodiode to break down and be damaged.

[0072] In view of this, please refer to Figure 4 As an optional implementation, the first detection module 13 further includes a second diode D2. The anode of the second diode D2 is connected to the cathode of the first optocoupler OC1, and the cathode of the second diode D2 is connected to the anode of the first optocoupler OC1. By connecting a second diode D2 in reverse parallel to the photodiode side of the first optocoupler OC1, protection is provided for the photodiode in the first optocoupler OC1.

[0073] Furthermore, the first detection module 13 also includes a third resistor R3. One end of the third resistor R3 is connected to the cathode of the first optocoupler OC1, and the other end of the third resistor R3 is connected to the output terminal of the positive bus relay 11 and one end of the first resistor R1.

[0074] As an alternative implementation, the second detection module 14 further includes a fourth diode D4. The anode of the fourth diode D4 is connected to the cathode of the second optocoupler OC2, and the cathode of the fourth diode D4 is connected to the anode of the second optocoupler OC2. By connecting a fourth diode D4 in reverse parallel to the photodiode side of the second optocoupler OC2, protection is provided for the photodiode in the second optocoupler OC2.

[0075] Furthermore, the second detection module 14 also includes a sixth resistor R6. One end of the sixth resistor R6 is connected to the cathode of the second optocoupler OC2, and the other end is connected to the input terminal of the negative bus relay 12. The third resistor R3 and the sixth resistor R6 are the current-limiting resistors at the cathodes of the first optocoupler OC1 and the second optocoupler OC2, respectively.

[0076] Based on the above design, the following is combined with Figure 5 and Figure 6 The overall working principle of the relay adhesion detection circuit 10 provided in the embodiments of this application will be explained.

[0077] like Figure 5 As shown, in the case of abnormal shutdown, if the positive bus relay 11 sticks together, the first optocoupler OC1 will be short-circuited. At this time, no current flows through the first optocoupler OC1 (i.e., the first optocoupler OC1 is cut off). The signal at the collector of the first optocoupler OC1 is pulled up to the high level VCC by the second resistor R2. The sticking fault of the positive bus relay 11 can be detected by the high-level signal output from the collector of the first optocoupler OC1.

[0078] Correspondingly, if the positive bus relay 11 is not stuck, the current flows out from the positive terminal of the battery 20, sequentially through the first diode D1, the first optocoupler OC1, the second resistor R2, and the first resistor R1, finally returning to the negative terminal of the battery 20. At this time, the first optocoupler OC1 is effectively driven (i.e., the first optocoupler OC1 is turned on), and the signal at the collector of the first optocoupler OC1 is pulled down to ground GND. The low-level signal output from the collector of the first optocoupler OC1 can be used to detect that the positive bus relay 11 has not experienced a sticking fault.

[0079] like Figure 6 As shown, under abnormal shutdown conditions, if the negative bus relay 12 sticks together, the second optocoupler OC2 will be short-circuited. At this time, no current flows through the second optocoupler OC2 (i.e., the second optocoupler OC2 is cut off). The signal at the collector of the second optocoupler OC2 is pulled high to the high level VCC by the fifth resistor R5. The sticking fault of the negative bus relay 12 can be detected by the high-level signal output from the collector of the second optocoupler OC2.

[0080] Correspondingly, if the negative bus relay 12 is not stuck, the current flows from the positive terminal of the battery 20, through the fourth resistor R4, the third diode D3, the second optocoupler OC2, and the sixth resistor R6 in sequence, and finally returns to the negative terminal of the battery 20. At this time, the second optocoupler OC2 is effectively driven (i.e., the second optocoupler OC2 is turned on), and the signal at the collector of the second optocoupler OC2 is pulled down to ground GND. The low-level signal output from the collector of the second optocoupler OC2 can be used to detect that the negative bus relay 12 has not experienced a sticking fault.

[0081] Optionally, please refer to Figure 7 This application also provides a relay adhesion detection system 100, which includes a battery 20, a bus capacitor 30, and a relay adhesion detection circuit 10 as described in any of the foregoing embodiments.

[0082] Furthermore, the relay adhesion detection system 100 also includes: a positive bus pre-charge relay 40, a negative bus pre-charge relay 50, a positive bus pre-charge resistor R7, and a negative bus pre-charge resistor R8.

[0083] One end of the positive bus pre-charge relay 40 is connected to the positive terminal of the battery 20, and the other end of the positive bus pre-charge relay 40 is connected to one end of the bus capacitor 30 through the positive bus pre-charge resistor R7. One end of the negative bus pre-charge relay 50 is connected to the negative terminal of the battery 20, and the other end of the negative bus pre-charge relay 50 is connected to the other end of the bus capacitor 30 through the negative bus pre-charge resistor R8.

[0084] The positive bus precharge relay 40 and the positive bus precharge resistor R7 constitute the positive bus precharge circuit, and the negative bus precharge relay 50 and the negative bus precharge resistor R8 constitute the negative bus precharge circuit. They are used to precharge the bus capacitor 30 when the high voltage is applied. After the precharge is completed, both the positive bus precharge relay 40 and the negative bus precharge relay 50 are disconnected.

[0085] In summary, this application provides a relay sticking detection circuit and system. The circuit includes a positive bus relay, a negative bus relay, a first detection module, and a second detection module. The input and output terminals of the positive bus relay are connected to the positive terminal of a battery and one end of a bus capacitor, respectively. The input and output terminals of the negative bus relay are connected to the negative terminal of a battery and the other end of the bus capacitor, respectively. The first terminal of the first detection module is connected to the input terminal of the positive bus relay, and the second terminal of the first detection module is connected to the output terminal of the positive bus relay and the input terminal of the negative bus relay, respectively. The first terminal of the second detection module is connected to the input terminal of the negative bus relay, and the second terminal of the second detection module is connected to the output terminal of the negative bus relay and the input terminal of the positive bus relay, respectively. The output terminal of the first detection module outputs a first level when a sticking fault occurs in the positive bus relay, and outputs a second level when no sticking fault occurs in the positive bus relay. The output terminal of the second detection module outputs a first level when a sticking fault occurs in the negative bus relay, and outputs a second level when no sticking fault occurs in the negative bus relay.

[0086] Compared to the feedback-contact relays used in existing technologies, the positive and negative bus relays in this embodiment are ordinary relays without feedback contacts. The level signal output by the first detection module can effectively detect the sticking state of the positive bus relay, and the level signal output by the second detection module can effectively detect the sticking state of the negative bus relay, thus realizing the sticking detection function of the feedback-free contact relay. The relay sticking detection circuit provided in this embodiment has a simple structure, eliminating the need for complex mechanical linkage design, reducing the overall system size and cost, and expanding the application range of low-cost feedback-free contact relays.

[0087] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

[0088] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this application. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A relay adhesion detection circuit, characterized in that, include: Positive busbar relay, negative busbar relay, first detection module, and second detection module; The input and output terminals of the positive bus relay are respectively connected to the positive terminal of the battery and one end of the bus capacitor, and the input and output terminals of the negative bus relay are respectively connected to the negative terminal of the battery and the other end of the bus capacitor. The first terminal of the first detection module is connected to the input terminal of the positive bus relay, and the second terminal of the first detection module is connected to the output terminal of the positive bus relay and the input terminal of the negative bus relay, respectively; the first terminal of the second detection module is connected to the input terminal of the negative bus relay, and the second terminal of the second detection module is connected to the output terminal of the negative bus relay and the input terminal of the positive bus relay, respectively. The output terminal of the first detection module is used to output a first level when the positive bus relay has a sticking fault, and to output a second level when the positive bus relay does not have a sticking fault; The output terminal of the second detection module is used to output a first level when the negative bus relay has a sticking fault, and to output a second level when the negative bus relay does not have a sticking fault.

2. The relay adhesion detection circuit according to claim 1, characterized in that, The relay adhesion detection circuit further includes a first resistor, and the first detection module includes a first optocoupler, a first diode, and a second resistor. The anode of the first diode is connected to the input terminal of the positive bus relay, the cathode of the first diode is connected to the anode of the first optocoupler, the cathode of the first optocoupler is connected to the output terminal of the positive bus relay and one end of the first resistor, and the other end of the first resistor is connected to the input terminal of the negative bus relay. The emitter of the first optocoupler is grounded, the collector of the first optocoupler is connected to one end of the second resistor, and the other end of the second resistor is connected to the power supply; wherein, the collector of the first optocoupler serves as the output terminal of the first detection module; When the positive bus relay experiences a sticking fault, the first optocoupler is cut off, and the collector of the first optocoupler outputs a high level. When the positive bus relay does not experience a sticking fault, the first optocoupler is turned on, and the collector of the first optocoupler outputs a low level.

3. The relay adhesion detection circuit according to claim 2, characterized in that, The first detection module further includes a second diode; the anode of the second diode is connected to the cathode of the first optocoupler, and the cathode of the second diode is connected to the anode of the first optocoupler.

4. The relay adhesion detection circuit according to claim 2, characterized in that, The first detection module further includes a third resistor; one end of the third resistor is connected to the cathode of the first optocoupler, and the other end of the third resistor is connected to the output terminal of the positive bus relay and one end of the first resistor, respectively.

5. The relay adhesion detection circuit according to claim 1, characterized in that, The relay adhesion detection circuit further includes a fourth resistor, and the second detection module includes a second optocoupler, a third diode, and a fifth resistor. The cathode of the second optocoupler is connected to the input terminal of the negative bus relay, and the anode of the second optocoupler is connected to the cathode of the third diode. The anode of the third diode is connected to the output terminal of the negative bus relay and one end of the fourth resistor, respectively. The other end of the fourth resistor is connected to the input terminal of the positive bus relay. The emitter of the second optocoupler is grounded, and the collector of the second optocoupler is connected to one end of the fifth resistor. The other end of the fifth resistor is connected to the power supply. The collector of the second optocoupler serves as the output terminal of the second detection module. When the negative bus relay experiences a sticking fault, the second optocoupler is cut off, and the collector of the second optocoupler outputs a high level. When the negative bus relay does not experience a sticking fault, the second optocoupler is turned on, and the collector of the second optocoupler outputs a low level.

6. The relay adhesion detection circuit according to claim 5, characterized in that, The second detection module further includes a fourth diode; the anode of the fourth diode is connected to the cathode of the second optocoupler, and the cathode of the fourth diode is connected to the anode of the second optocoupler.

7. The relay adhesion detection circuit according to claim 5, characterized in that, The second detection module further includes a sixth resistor; one end of the sixth resistor is connected to the cathode of the second optocoupler, and the other end of the sixth resistor is connected to the input terminal of the negative bus relay.

8. The relay adhesion detection circuit according to claim 1, characterized in that, The relay adhesion detection circuit further includes a control detection module; the first input terminal of the control detection module is connected to the output terminal of the first detection module, and the second input terminal of the control detection module is connected to the output terminal of the second detection module. The control detection module is used to determine the adhesion state of the positive bus relay based on the level signal output by the first detection module, and to determine the adhesion state of the negative bus relay based on the level signal output by the second detection module.

9. A relay adhesion detection system, characterized in that, include: The battery, the bus capacitor, and the relay adhesion detection circuit as described in any one of claims 1-8.

10. The relay adhesion detection system according to claim 9, characterized in that, The relay adhesion detection system further includes: a positive busbar pre-charge relay, a negative busbar pre-charge relay, a positive busbar pre-charge resistor, and a negative busbar pre-charge resistor; One end of the positive bus precharge relay is connected to the positive terminal of the battery, and the other end of the positive bus precharge relay is connected to one end of the bus capacitor through the positive bus precharge resistor. One end of the negative bus precharge relay is connected to the negative terminal of the battery, and the other end of the negative bus precharge relay is connected to the other end of the bus capacitor through the negative bus precharge resistor.

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