Adhesion detection circuit suitable for multi-branch parallel relays and method

Abstract

An adhesion detection circuit suitable for multi-branch parallel relays and a method. The adhesion detection circuit comprises: a first detection circuit, used for being connected to a first auxiliary contact of a relay; and a second detection circuit, used for being connected to a second auxiliary contact of the relay. When an input end of the first detection circuit receives a high-level signal, an output end of the first detection circuit outputs a high level to the first auxiliary contact of the relay; when an input end of the second detection circuit receives a high-level signal from the second auxiliary contact of the relay, an output end of the second detection circuit outputs a low-level signal; when the input end of the first detection circuit receives a low-level signal, the output end of the first detection circuit outputs a low level to the first auxiliary contact of the relay; and when the input end of the second detection circuit receives a low-level signal from the second auxiliary contact of the relay, the output end of the second detection circuit outputs a high-level signal. The detection circuit and the method have high independence in determining faults in parallel relays and high reliability.

Description

A circuit and method for detecting adhesion of multi-branch parallel relays

[0001] The application claims priority to Chinese Patent Application No. 202411837947.8, filed on December 13, 2024, entitled "A Circuit and Method for Detecting Adhesion of Multi-Branch Parallel Relays", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention belongs to the field of electric vehicle technology, specifically relating to a sticking detection circuit and method suitable for multi-branch parallel relays. Background Technology

[0003] In the field of electric buses, multiple high-voltage systems are often connected in parallel, corresponding to the need for multiple parallel branch positive relay control and judgment of their working status. Relay sticking detection is one of the basic functions that the battery pack must complete during power-on self-test. The mainstream relay sticking detection circuit is shown in Figure 1. After the battery management system is powered on, it detects the voltage V1 of the battery positive terminal (BAT+ in Figure 1) through the ADC port with the negative terminal of the battery (BAT- in Figure 1) as the reference voltage point. Before sending the closing command to the pre-charge relay and the main positive relay (B+ in Figure 1), the voltage values ​​are compared. If V2 > 98% * V1, then at least one of the main positive relays or the pre-charge relay has a relay sticking fault. Because the pre-charge relay is connected in series with the pre-charge resistor R, under normal circumstances, the pre-charge resistor R is not short-circuited, and the pre-charge relay will not stick. Generally, it is considered that the main positive relay has a sticking fault. However, at the moment of sticking fault, this scheme cannot directly determine which of the main positive relays or the pre-charge relay is sticking and causing the V2 voltage to rise. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a sticking detection circuit and method applicable to multi-branch parallel relays, which provides high independence and reliability in fault diagnosis of parallel relays.

[0005] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0006] In a first aspect, the present invention provides a sticking detection circuit suitable for multi-branch parallel relays, comprising:

[0007] The first detection circuit is used to connect to the first auxiliary contact of the relay;

[0008] The second detection circuit is used to connect to the second auxiliary contact of the relay;

[0009] When the input terminal of the first detection circuit receives a high-level signal, its output terminal outputs a high-level signal to the first auxiliary contact of the relay.

[0010] When the input terminal of the second detection circuit receives a high-level signal from the second auxiliary contact of the relay, its output terminal outputs a low-level signal.

[0011] When the input terminal of the first detection circuit receives a low-level signal, its output terminal outputs a low-level signal to the first auxiliary contact of the relay.

[0012] When the input terminal of the second detection circuit receives a low-level signal from the second auxiliary contact of the relay, its output terminal outputs a high-level signal.

[0013] In the above scheme, the first detection circuit and the second detection circuit are respectively connected to the two auxiliary contacts of the same relay to detect whether a single relay is stuck. This scheme can realize the independent detection of multiple relays, and the corresponding multiple branches do not interfere with each other. It has strong independence, is easy to reuse, and has high reliability.

[0014] In conjunction with the first aspect, optionally, the first detection circuit includes an NPN type first transistor, a second transistor, a third transistor, and a PNP type fourth transistor;

[0015] The bases of the first transistor and the second transistor are connected to form the input terminal of the first detection circuit, which is used to connect to the controller and receive high-level signals or low-level signals.

[0016] The collector of the first transistor is connected to one end of the first resistor, the other end of the first resistor is connected to the base of the third transistor, and the emitter of the first transistor is grounded.

[0017] The emitter of the third transistor is used to receive a 24V voltage signal, its collector is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the cathode of the first diode, and the anode of the first diode is connected to the collector of the fourth transistor, forming the output terminal of the first detection circuit.

[0018] The collector of the second transistor is connected to one end of the second resistor and one end of the third resistor, respectively, and the other end of the second resistor is connected to a 3.3V voltage signal; the other end of the third resistor is connected to the base of the fourth transistor and one end of the fourth resistor, respectively; the emitter of the second transistor is grounded; the other end of the fourth resistor and the emitter of the fourth transistor are both grounded.

[0019] In the above scheme, when the input terminal of the first detection circuit receives a high level, the first and second transistors are simultaneously in the conducting state, causing the third and fourth resistors to act as bias resistors for the fourth transistor. The voltage levels across the third and fourth resistors are pulled to 0V, so the fourth transistor is in the cut-off state. The third transistor has two internal bias resistors, and the first resistor configures the third transistor to be in a saturated conducting state. The 24V voltage passes through the emitter to the collector of the third transistor, then through the fifth resistor and the first diode, and finally outputs a 24V high level through the output terminal of the first detection circuit. When the input terminal of the first detection circuit receives a low level, the first and second transistors are simultaneously in the cut-off state, causing the third transistor to be in the cut-off state. At this time, the base of the fourth transistor is pulled up by a 3.3V voltage, and through the third and fourth resistors, it is made to be in a fully saturated conducting state, and then connected to GND, outputting a 0V low level through the output terminal of the first detection circuit.

[0020] In conjunction with the first aspect, optionally, the first detection circuit further includes a first protection circuit, the first protection circuit including a second diode, the positive terminal of the second diode being grounded, and the negative terminal being connected to the output terminal of the first detection circuit.

[0021] In the above scheme, the output terminal of the first detection circuit is protected by the second diode. The second diode has an SMA package size and a rated operating voltage of 33V.

[0022] In conjunction with the first aspect, the first detection circuit may optionally further include a voltage divider circuit and a first filter circuit;

[0023] The voltage divider circuit includes a sixth resistor and a seventh resistor; one end of the sixth resistor is connected to the output terminal of the first detection circuit, and the other end is connected to one end of the seventh resistor, with the other end of the seventh resistor grounded.

[0024] The first filter circuit includes an eighth resistor and a first capacitor. One end of the eighth resistor is connected to the connection point between the sixth and seventh resistors, and the other end is connected to one end of the first capacitor to form an output voltage detection point. The other end of the first capacitor is grounded.

[0025] In the above scheme, the output voltage of the first detection circuit is monitored using the sixth and seventh resistors. When the output voltage detection point continuously outputs a signal, it indicates that the first detection circuit is in a normal state. In practical implementation, the output voltage detection point is generally connected to the Opti1_ADC port of the controller, thereby realizing the ADC retrieval function, which can self-check for hardware faults in the bonding circuit and improve the safety level. Furthermore, a first filtering circuit is set up to filter and protect the Opti1_ADC port of the controller.

[0026] In conjunction with the first aspect, optionally, the second detection circuit includes: an NPN type fifth transistor and a reverse breakdown diode;

[0027] The base of the fifth transistor is connected to the negative terminal of the reverse breakdown diode, its emitter is grounded, and one end of its collector is connected to one end of the ninth resistor, serving as the output terminal of the second detection circuit; the other end of the ninth resistor is used to connect to a 3V voltage.

[0028] The positive terminal of the reverse breakdown diode is used as the input terminal of the second detection circuit.

[0029] In the above scheme, when the input terminal of the second detection circuit receives a high-level signal from the second auxiliary contact of the relay, the fifth transistor is turned on after the diode is reverse-broken down, and the output terminal of the second detection circuit outputs a low level of 0V. When the input terminal of the second detection circuit receives a high-level signal from the second auxiliary contact of the relay, the fifth transistor is turned off after the diode is reverse-broken down, causing the collector and emitter to be unable to conduct. Therefore, through the pull-up voltage of the ninth resistor, the output terminal of the second detection circuit outputs a high level of 3.3V.

[0030] In conjunction with the first aspect, optionally, the second detection circuit further includes a second protection circuit, which includes a second capacitor and a third diode; one end of the second capacitor is connected to the positive terminal of the third diode and then grounded, and the other end is connected to the negative terminal of the third diode and then connected to the positive terminal of the breakdown diode.

[0031] In the above scheme, the second capacitor and the third diode work together to protect the input signal received by the second detection circuit. The third diode has an SMA package size and a rated operating voltage of 33V.

[0032] In conjunction with the first aspect, the second detection circuit may optionally further include a second filter circuit, which includes a tenth resistor and a third capacitor;

[0033] One end of the tenth resistor is connected to the base of the fifth transistor and one end of the third capacitor, respectively, and the other end is connected to the negative terminal of the reverse breakdown diode; the other end of the third capacitor is connected to the emitter of the fifth transistor.

[0034] In the above scheme, the second filtering circuit is used to filter and protect the signal received by the second detection circuit.

[0035] Secondly, the present invention provides a detection method based on the adhesion detection circuit described in any one of the first aspects, comprising:

[0036] The duty cycle is calculated based on the low-level and high-level signals output by the second detection circuit.

[0037] When the calculated duty cycle is within the preset duty cycle range, it means that the auxiliary contacts of the relay are in the closed state and the main contacts of the relay are in the open state, and the relay is determined to be non-stick.

[0038] If the calculated duty cycle is outside the preset duty cycle range, it indicates that the relay's auxiliary contacts are in the open state and the relay's main contacts are in the closed state, indicating that the relay is stuck.

[0039] In the above scheme, the first detection circuit and the second detection circuit are respectively connected to the two auxiliary contacts of the same relay to detect whether a single relay is stuck. This scheme can realize the independent detection of multiple relays, and the corresponding multiple branches do not interfere with each other. It has strong independence, is easy to reuse, and has high reliability.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] This invention utilizes a first detection circuit and a second detection circuit, which are respectively connected to two auxiliary contacts of the same relay, to detect whether a single relay is stuck together. This solution can realize independent detection of multiple relays, with multiple branches not interfering with each other, strong independence, easy reuse, and high reliability.

[0042] This invention features ADC retrieval functionality, enabling self-detection of hardware faults in the sticky circuit and improving safety levels. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0044] Figure 1 is a schematic diagram of a detection circuit in the prior art;

[0045] Figure 2 is a circuit diagram of the first detection circuit according to an embodiment of the present invention;

[0046] Figure 3 is a circuit diagram of the second detection circuit according to an embodiment of the present invention;

[0047] Figure 4 is a schematic diagram of the adhesion detection circuit according to an embodiment of the present invention;

[0048] Figure 5 shows the internal structure of a relay with auxiliary contacts. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may include different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0051] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0052] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0053] The application principle of the present invention will be described in detail below with reference to the accompanying drawings.

[0054] Example 1

[0055] This invention provides an adhesion detection circuit suitable for multi-branch parallel relays, as shown in Figures 2 and 3, including: a first detection circuit and a second detection circuit;

[0056] The first detection circuit is used to connect to the first auxiliary contact of the relay;

[0057] The second detection circuit is used to connect to the second auxiliary contact of the relay;

[0058] When the input terminal of the first detection circuit receives a high-level signal, its output terminal outputs a high-level signal to the first auxiliary contact of the relay.

[0059] When the input terminal of the second detection circuit receives a high-level signal from the second auxiliary contact of the relay, its output terminal outputs a low-level signal.

[0060] When the input terminal of the first detection circuit receives a low-level signal, its output terminal outputs a low-level signal to the first auxiliary contact of the relay.

[0061] When the input terminal of the second detection circuit receives a low-level signal from the second auxiliary contact of the relay, its output terminal outputs a high-level signal.

[0062] In the above scheme, the first detection circuit and the second detection circuit are respectively connected to the two auxiliary contacts of the same relay to detect whether a single relay is stuck. This scheme can realize the independent detection of multiple relays, and the corresponding multiple branches do not interfere with each other. It has strong independence, is easy to reuse, and has high reliability.

[0063] In one specific embodiment of the present invention, as shown in FIG2, the first detection circuit includes an NPN type first transistor Q6201, a second transistor Q6204, a third transistor Q6200, and a PNP type fourth transistor Q6203; the first transistor Q6201, the second transistor Q6204, and the third transistor Q6200 are all provided with bias resistors inside;

[0064] The bases of the first transistor Q6201 and the second transistor Q6204 are connected to form the input terminal of the first detection circuit, which is used to connect to the controller (i.e., the MCU chip inside the BMS host in Figure 4) to receive high-level signals or low-level signals.

[0065] The collector of the first transistor Q6201 is connected to one end of the first resistor R6226, the other end of the first resistor R6226 is connected to the base of the third transistor Q6200, and the emitter of the first transistor Q6201 is grounded.

[0066] The emitter of the third transistor Q6200 is used to receive a 24V voltage signal (i.e., the KL30 signal), and its collector is connected to one end of the fifth resistor R6200. The other end of the fifth resistor R6200 is connected to the cathode of the first diode D6200, and the anode of the first diode D6200 is connected to the collector of the fourth transistor Q6203, forming the output terminal of the first detection circuit.

[0067] The collector of the second transistor Q6204 is connected to one end of the second resistor R6210 and the third resistor R6211, respectively. The other end of the second resistor R6210 is connected to a 3.3V voltage signal. The other end of the third resistor R6211 is connected to the base of the fourth transistor Q6203 and one end of the fourth resistor R6212, respectively. The emitter of the second transistor Q6204 is grounded. The other end of the fourth resistor R6212 and the emitter of the fourth transistor Q6203 are both grounded.

[0068] In the above scheme, when the input terminal of the first detection circuit receives a high level (i.e., the PWM_OUT_EN1 pin in Figure 2 receives a high level from the controller), the first transistor Q6201 and the second transistor Q6204 are simultaneously in the conducting state. This causes the third resistor R6211 (which can be set to 10KΩ in specific applications) and the fourth resistor R6212 (which can be set to 10KΩ in specific applications) to act as bias resistors for the fourth transistor Q6203. The voltage levels across the third resistor R6211 and the fourth resistor R6212 are pulled to 0V, so the fourth transistor Q6203 is in the cut-off state. The third transistor Q6200 has two internal bias resistors (which can be set to 10KΩ in specific applications), and the first resistor R6226 (which can be set to 10KΩ in specific applications) configures the third transistor Q6200 to be in the saturated conducting state. The 24V voltage passes through the third transistor... The emitter (pin 2) of transistor Q6200 is connected to the collector (pin 3), then through the fifth resistor R6200 (which can be set to 10KΩ in specific applications) and the first diode D6200, and finally outputs a 24V high level through the output terminal of the first detection circuit (i.e., outputs a 24V high level through PWM_OUT1 in Figure 2). When the input terminal of the first detection circuit receives a low level (i.e., the PWM_OUT_EN1 pin in Figure 2 receives a low level from the controller), the first transistor Q6201 and the second transistor are simultaneously cut off, causing the third transistor Q6200 to be cut off. At this time, the base of the fourth transistor Q6203 is pulled up by a 3.3V voltage, and through the third resistor R6211 and the fourth resistor R6212, it is made to be fully saturated and conducting, and then connected to GND, outputting a 0V low level through the output terminal of the first detection circuit (i.e., PWM_OUT1 outputs a 0V low level). In practice, the resistance of the second resistor R6210 can be set to 1kΩ.

[0069] In one specific embodiment of the present invention, as shown in FIG2, the first detection circuit further includes a first protection circuit, the first protection circuit including a second diode D6202, the positive terminal of the second diode D6202 being grounded, and the negative terminal being connected to the output terminal of the first detection circuit.

[0070] In the above scheme, the output terminal of the first detection circuit is protected by the second diode D6202. The second diode D6202 has an SMA package size and a rated operating voltage of 33V.

[0071] In one specific embodiment of the present invention, as shown in FIG2, the first detection circuit further includes a voltage divider circuit and a first filter circuit.

[0072] The voltage divider circuit includes a sixth resistor R6204 and a seventh resistor R6206; one end of the sixth resistor R6204 is connected to the output terminal of the first detection circuit, and the other end is connected to one end of the seventh resistor R6206, and the other end of the seventh resistor R6206 is grounded.

[0073] The first filter circuit includes an eighth resistor R6205 and a first capacitor C6201. One end of the eighth resistor R6205 is connected to the connection point between the sixth resistor R6204 and the seventh resistor R6206, and the other end is connected to one end of the first capacitor C6201 to form an output voltage detection point. The other end of the first capacitor C6201 is grounded. In a specific implementation, the eighth resistor R6205 can be set to 10kΩ, and the first capacitor C6201 can be set to 10nF.

[0074] In the above scheme, the output voltage of the first detection circuit is monitored using the sixth resistor R6204 and the seventh resistor R6206. When the output voltage detection point continuously outputs a signal, it indicates that the first detection circuit is in a normal state. In practical implementation, the output voltage detection point is generally connected to the controller's Opt1_ADC port. The real-time voltage retracement of the Opt1_ADC port is used to monitor whether the output function of the first detection circuit is normal, thus realizing the ADC retracement function. This allows for self-checking of hardware faults in the stuck circuit, improving the safety level. Furthermore, a first filtering circuit is set up to filter and protect the controller's Opt1_ADC port. In specific applications, the sixth resistor R6204 is 33kΩ, and the seventh resistor R6206 is 4.7kΩ.

[0075] In one specific embodiment of the present invention, as shown in FIG3, the second detection circuit includes: an NPN type fifth transistor Q6202 and a reverse breakdown diode Z6200;

[0076] The base of the fifth transistor Q6202 is connected to the negative terminal of the reverse breakdown diode Z6200, its emitter is grounded, and one end of its collector is connected to one end of the ninth resistor R6207, which is used as the output terminal of the second detection circuit (i.e., Input1_MCU in Figure 3); the other end of the ninth resistor R6207 is used to connect to a 3V voltage.

[0077] The positive terminal of the reverse breakdown diode Z6200 is used as the input terminal of the second detection circuit (i.e., PWMIN1 in Figure 3).

[0078] In the above scheme, when the input terminal of the second detection circuit receives a high-level signal from the second auxiliary contact of the relay, the fifth transistor Q6202 is turned on after reverse breakdown of the diode, and the output terminal of the second detection circuit outputs a 0V low level to the MCU chip inside the BMS host. When the input terminal of the second detection circuit receives a high-level signal from the second auxiliary contact of the relay, the fifth transistor Q6202 is turned off after reverse breakdown of the diode, causing the collector and emitter of the fifth transistor Q6202 to be unable to conduct. Therefore, the voltage is pulled up through the pull-up resistor R6207, and the output terminal of the second detection circuit outputs a 3.3V high level. In the specific implementation, the reverse breakdown diode Z6200 is packaged as SOD123 with a rated breakdown voltage of 2V. In the specific implementation, the resistance of the ninth resistor R6207 is 10kΩ.

[0079] In one specific embodiment of the present invention, as shown in FIG3, the second detection circuit further includes a second protection circuit, which includes a second capacitor C6203 and a third diode D6201; one end of the second capacitor C6203 is connected to the positive terminal of the third diode D6201 and then grounded, and the other end is connected to the negative terminal of the third diode D6201 and then connected to the positive terminal of the breakdown diode.

[0080] In the above scheme, the second capacitor C6203 and the third diode D6201 work together to protect the input signal received by the second detection circuit. The third diode D6201 has an SMA package size and a rated operating voltage of 33V. In specific implementation, the second capacitor C6203 can be set to 10nF.

[0081] In one specific embodiment of the present invention, as shown in FIG3, the second detection circuit further includes a second filter circuit, which includes: a tenth resistor R6209 and a third capacitor C6202.

[0082] One end of the tenth resistor R6209 is connected to the base of the fifth transistor Q6202 and one end of the third capacitor C6202, respectively, and the other end is connected to the negative terminal of the reverse breakdown diode Z6200; the other end of the third capacitor C6202 is connected to the emitter of the fifth transistor Q6202.

[0083] In the above scheme, the second filter circuit is used to filter and protect the signal received by the second detection circuit. In specific implementation, the resistance value of the tenth resistor R6209 can be set to 10KΩ, and the third capacitor C6202 can be set to 10nF.

[0084] In the specific implementation process, a relay is connected in series in each branch. As shown in Figure 4, three relays are used as an example for explanation. The three relays are denoted as S1, S2 and S3, and are connected to drive lines HSD and KL31 respectively. HV1, HV2, HV4, HV5 and HV6 are high voltage detection points. PWM_OUT is used to connect to the output terminal of the first detection circuit, PWM_IN is used to connect to the input terminal of the second detection circuit, M1 is the vehicle motor load, Pre-RES is the pre-charge resistor of the battery pack, shunt is the current sensor of the battery pack, and PACK- is the total negative reference point of the battery pack. There are also three main positive, main negative and pre-charge relays, Pack1, Pack2 and Pack3 are three electrical test packs, and Fuse1, Fuse2 and Fuse3 are three fuses in the battery pack. All three relays have auxiliary contacts. The internal structure of the relay is shown in Figure 5. The state of the auxiliary contacts is opposite to the state of the main contacts of the actual relays, that is, the main contacts are open and the auxiliary contacts are closed, and the main contacts are closed and the auxiliary contacts are open. The relay is connected in series in the branch circuit. The two main contacts of the relay are connected to the branch circuit respectively, and the two auxiliary contacts of the relay are connected to the adhesion detection circuit proposed in the embodiment of the present invention.

[0085] Based on the low-level and high-level signals output by the second detection circuit, the duty cycle is calculated. When the calculated duty cycle is within a preset duty cycle range (e.g., 40%-60%), it indicates that the relay's auxiliary contacts are closed and the relay's main contacts are open, indicating that the relay is not stuck. When the calculated duty cycle is outside the preset duty cycle range, it indicates that the relay's auxiliary contacts are open and the relay's main contacts are closed, indicating that the relay is stuck. The duty cycle range is set according to actual needs.

[0086] Example 2

[0087] This invention provides a detection method based on the adhesion detection circuit described in any one of Embodiments 1, comprising the following steps:

[0088] (1) Calculate the duty cycle based on the low-level signal and high-level signal output by the second detection circuit;

[0089] (2) When the calculated duty cycle is within the preset duty cycle range, it means that the auxiliary contact of the relay is in the closed state and the main contact of the relay is in the open state, and the relay is determined to be non-stick.

[0090] (3) When the calculated duty cycle is outside the preset duty cycle range, it means that the auxiliary contact of the relay is in the open state and the main contact of the relay is in the closed state, and the relay is determined to be stuck.

[0091] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of the present invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of the present invention.

[0092] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents. Industrial applicability:

[0093] The solution provided in this application embodiment can be applied to the field of electric vehicle technology. In this application embodiment, the first detection circuit and the second detection circuit are respectively connected to the two auxiliary contacts of the same relay to detect whether a single relay is stuck. This solution can realize the independent detection of multiple relays, and the corresponding multiple branches do not interfere with each other. It has strong independence, is easy to reuse, and has high reliability.

Claims

1. A sticking detection circuit suitable for multi-branch parallel relays, comprising: The first detection circuit is used to connect to the first auxiliary contact of the relay; The second detection circuit is used to connect to the second auxiliary contact of the relay; When the input terminal of the first detection circuit receives a high-level signal, its output terminal outputs a high-level signal to the first auxiliary contact of the relay. When the input terminal of the second detection circuit receives a high-level signal from the second auxiliary contact of the relay, its output terminal outputs a low-level signal. When the input terminal of the first detection circuit receives a low-level signal, its output terminal outputs a low-level signal to the first auxiliary contact of the relay. When the input terminal of the second detection circuit receives a low-level signal from the second auxiliary contact of the relay, its output terminal outputs a high-level signal.

2. The adhesion detection circuit for multi-branch parallel relays according to claim 1, wherein: The first detection circuit includes an NPN type first transistor, a second transistor, a third transistor, and a PNP type fourth transistor; The bases of the first transistor and the second transistor are connected to form the input terminal of the first detection circuit, which is used to connect to the controller and receive high-level signals or low-level signals. The collector of the first transistor is connected to one end of the first resistor, the other end of the first resistor is connected to the base of the third transistor, and the emitter of the first transistor is grounded. The emitter of the third transistor is used to receive a 24V voltage signal, its collector is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the cathode of the first diode, and the anode of the first diode is connected to the collector of the fourth transistor, forming the output terminal of the first detection circuit. The collector of the second transistor is connected to one end of the second resistor and one end of the third resistor, respectively, and the other end of the second resistor is connected to a 3.3V voltage signal; the other end of the third resistor is connected to the base of the fourth transistor and one end of the fourth resistor, respectively; the emitter of the second transistor is grounded; the other end of the fourth resistor and the emitter of the fourth transistor are both grounded.

3. The adhesion detection circuit for multi-branch parallel relays according to claim 2, wherein: The first detection circuit further includes a first protection circuit, which includes a second diode. The positive terminal of the second diode is grounded, and the negative terminal is connected to the output terminal of the first detection circuit.

4. A sticking detection circuit suitable for multi-branch parallel relays according to claim 2 or 3, wherein: The first detection circuit also includes a voltage divider circuit and a first filter circuit; The voltage divider circuit includes a sixth resistor and a seventh resistor; one end of the sixth resistor is connected to the output terminal of the first detection circuit, and the other end is connected to one end of the seventh resistor, with the other end of the seventh resistor grounded. The first filter circuit includes an eighth resistor and a first capacitor. One end of the eighth resistor is connected to the connection point between the sixth and seventh resistors, and the other end is connected to one end of the first capacitor to form an output voltage detection point. The other end of the first capacitor is grounded.

5. A sticking detection circuit suitable for multi-branch parallel relays according to claim 2, wherein, When the input terminal of the first detection circuit receives a high level, the first transistor and the second transistor are simultaneously in the conducting state, causing the third resistor and the fourth resistor to act as bias resistors for the fourth transistor. The voltage levels across the third resistor and the fourth resistor are pulled to 0V, so the fourth transistor is in the cut-off state. The third transistor has two internal bias resistors, and the first resistor configures the third transistor to be in the saturated conducting state. The 24V voltage passes through the emitter to the collector of the third transistor, then through the fifth resistor and the first diode, and finally outputs a 24V high level through the output terminal of the first detection circuit. When the input terminal of the first detection circuit receives a low level, the first transistor and the second transistor are simultaneously cut off, causing the third transistor to be cut off. At this time, the base of the fourth transistor is pulled up by a 3.3V voltage, and through the third resistor and the fourth resistor, it is made to be in a fully saturated conduction state and directly grounded, outputting a 0V low level through the output terminal of the first detection circuit.

6. The adhesion detection circuit for multi-branch parallel relays according to claim 1, wherein, The second detection circuit includes: an NPN type fifth transistor and a reverse breakdown diode; The base of the fifth transistor is connected to the negative terminal of the reverse breakdown diode, its emitter is grounded, and one end of its collector is connected to one end of the ninth resistor, serving as the output terminal of the second detection circuit; the other end of the ninth resistor is used to connect to a 3V voltage. The positive terminal of the reverse breakdown diode is used as the input terminal of the second detection circuit.

7. A sticking detection circuit for multi-branch parallel relays according to claim 5, wherein: The second detection circuit also includes a second protection circuit, which includes a second capacitor and a third diode; one end of the second capacitor is connected to the positive terminal of the third diode and then grounded, and the other end is connected to the negative terminal of the third diode and then connected to the positive terminal of the breakdown diode.

8. A sticking detection circuit for multi-branch parallel relays according to claim 5 or 6, wherein: The second detection circuit further includes a second filter circuit, which includes a tenth resistor and a third capacitor; One end of the tenth resistor is connected to the base of the fifth transistor and one end of the third capacitor, respectively, and the other end is connected to the negative terminal of the reverse breakdown diode; the other end of the third capacitor is connected to the emitter of the fifth transistor.

9. A sticking detection circuit for multi-branch parallel relays according to claim 1, wherein: When the input terminal of the second detection circuit receives a high-level signal from the second auxiliary contact of the relay, the fifth transistor is turned on after the diode is reversed and broken down. The output terminal of the second detection circuit outputs a low level of 0V. When the input terminal of the second detection circuit receives a high-level signal from the second auxiliary contact of the relay, the fifth transistor is cut off after the diode is reversed, causing the collector and emitter to be unable to conduct. Therefore, through the pull-up voltage of the ninth resistor, the output terminal of the second detection circuit outputs a 3.3V high level.

10. A detection method based on the adhesion detection circuit according to any one of claims 1-9, comprising: The duty cycle is calculated based on the low-level and high-level signals output by the second detection circuit. When the calculated duty cycle is within the preset duty cycle range, it means that the auxiliary contacts of the relay are in the closed state and the main contacts of the relay are in the open state, and the relay is determined to be non-stick. If the calculated duty cycle is outside the preset duty cycle range, it indicates that the relay's auxiliary contacts are in the open state and the relay's main contacts are in the closed state, indicating that the relay is stuck.

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