Relay state detection circuit and detection method

Abstract

This invention discloses a relay status detection circuit and method, including a battery pack, multiple relays, multiple diagnostic circuits, a first resistor, and a first capacitor. The positive terminal of the battery pack is connected to one end of a first main relay, and the negative terminal of the battery pack is connected to one end of a second main relay. One end of the first diagnostic circuit, a first charging relay, the first resistor, and the first capacitor are respectively connected to the other end of the first main relay. One end of the second charging relay, the other end of the first diagnostic circuit, the first resistor, and the first capacitor are respectively connected to the other end of the second main relay. The other end of the first charging relay is connected to the positive terminal of a third diagnostic circuit and a charging interface, and the other end of the second charging relay is connected to the negative terminal of a fourth diagnostic circuit and a charging interface. Through this method, the residual voltage of the vehicle's load capacitor discharge circuit is used to determine the status of the positive and negative charging relays.

Description

Technical Field

[0001] This invention relates to the field of relay detection technology, and in particular to a relay status detection circuit and detection method. Background Technology

[0002] With the continuous development of the new energy industry, the safety performance requirements for electric vehicles are also gradually increasing. The safety performance of the high-voltage system in electric vehicles is becoming increasingly important. As the switch that supplies power from the battery pack to the external load, the reliability of the high-voltage DC contactor is crucial. For contactor status detection, such as normal operation and failure states (failure to engage or disengage), the controller must make accurate judgments and promptly feed back the contactor's status to the driver to reduce safety risks. Traditional methods of measuring voltage to determine the charging relay status are susceptible to interference from the residual voltage of the load capacitor, which can affect the accuracy of the data acquisition. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a relay state detection circuit and method, which solves the problem in the prior art where inaccurate judgment of the state of the charging relay is caused by interference.

[0004] A first aspect of this invention provides a relay state detection circuit, the circuit including a battery pack (100), a plurality of relays, a plurality of diagnostic circuits, a first resistor (401) and a first capacitor (500).

[0005] Among them, the multiple relays include a first main relay (301), a second main relay (302), a first charging relay (303), and a second charging relay (304), and the multiple diagnostic circuits include a first diagnostic circuit, a third diagnostic circuit, and a fourth diagnostic circuit.

[0006] The positive terminal of the battery pack (100) is connected to one end of the first main relay (301), and the negative terminal of the battery pack (100) is connected to one end of the second main relay (302);

[0007] One end of the first diagnostic circuit, one end of the first charging relay (303), one end of the first resistor (401), and one end of the first capacitor (500) are respectively connected to the other end of the first main relay (301);

[0008] The other end of the first diagnostic circuit, one end of the second charging relay (304), the other end of the first resistor (401), and the other end of the first capacitor (500) are respectively connected to the other end of the second main relay (302);

[0009] The other end of the first charging relay (303) is connected to the positive terminal (701) of the third diagnostic circuit and the vehicle's charging interface, and the other end of the second charging relay (304) is connected to the negative terminal (702) of the fourth diagnostic circuit and the vehicle's charging interface.

[0010] In one possible implementation of the first aspect, the first diagnostic circuit includes a second resistor (402), a third resistor (403), a fourth resistor (404), a fifth resistor (405), and a first reference source (201).

[0011] Among them, one end of the second resistor (402) is connected to the other end of the first main relay (301), the other end of the second resistor (402) is connected to one end of the third resistor (403), the other end of the third resistor (403) is connected to the first reference source (201), and the second resistor (402) and the third resistor (403) are connected in series.

[0012] The other end of the fifth resistor (405) is connected to the other end of the second main relay (302), one end of the fifth resistor (405) is connected to one end of the fourth resistor (404), the other end of the fourth resistor (404) is connected to the first reference source (201), and the fifth resistor (405) and the fourth resistor (404) are connected in series.

[0013] In one possible implementation of the first aspect, the diagnostic circuit further includes a second diagnostic circuit connected to the other end of the first charging relay (303), wherein,

[0014] The second diagnostic circuit includes a sixth resistor (406) and a seventh resistor (407), which are connected in series.

[0015] In one possible implementation of the first aspect, the third diagnostic circuit includes an eighth resistor (408), a ninth resistor (409), and a first analog-to-digital converter (601), one end of which is connected to a node between the eighth resistor (408) and the ninth resistor (409), which are connected in series.

[0016] In one possible implementation of the first aspect, the fourth diagnostic circuit includes a second reference source (202), a tenth resistor (410), an eleventh resistor (411), a twelfth resistor (412), a diode (800), and a second analog-to-digital converter (602).

[0017] One end of the tenth resistor (410) is connected to the positive terminal of the second reference source (202), and the other end of the tenth resistor (410) is connected to the input terminal of the second analog-to-digital converter (602).

[0018] One end of the eleventh resistor (411) is connected to the anode of the diode (800), the cathode of the diode (800) is connected to one end of the twelfth resistor (412), and the other end of the twelfth resistor (412) is connected to the other end of the second charging relay (304).

[0019] The tenth resistor (410) and the eleventh resistor (411) are connected in series, and the eleventh resistor (411) and the twelfth resistor (412) are connected in parallel.

[0020] To address the same technical problem, a second aspect of the present invention provides a relay state detection method, the method comprising:

[0021] Based on the first voltage value in the first diagnostic circuit, the third voltage value obtained by the third diagnostic circuit, or the fourth voltage value obtained by the fourth diagnostic circuit, a first diagnostic result is obtained.

[0022] A second diagnostic result is obtained based on the fourth voltage value obtained from the fourth diagnostic circuit or the second voltage value obtained from the second diagnostic circuit.

[0023] The status of the charging relay is determined based on the first and second diagnostic results.

[0024] In one possible implementation of the second aspect, determining the state of the charging relay based on the first diagnostic result and the second diagnostic result includes:

[0025] When the vehicle is powered on, the first charging relay (303) is set to the closed state and the second charging relay (304) is set to the closed state. If the first diagnostic result is the first preset value and the second diagnostic result is the second preset value, then the first charging relay (303) and the second charging relay (304) are judged to be in normal state.

[0026] When the vehicle is powered on, the first charging relay (303) is set to the closed state and the second charging relay (304) is set to the closed state. If the first diagnostic result is 0V and the second diagnostic result is the third preset value, then the first charging relay (303) and the second charging relay (304) are judged to be in a fault state.

[0027] When the vehicle is powered on, the first charging relay (303) is set to the closed state and the second charging relay (304) is set to the closed state. If the first diagnostic result is the first preset value and the second diagnostic result is the third preset value, then the first charging relay (303) is judged to be in a normal state and the second charging relay (304) is in a fault state.

[0028] When the vehicle is powered on, the first charging relay (303) is set to the closed state and the second charging relay (304) is set to the closed state. If the first diagnostic result is 0V and the second diagnostic result is the second preset value, then the first charging relay (303) is judged to be in a fault state and the second charging relay (304) is in a normal state.

[0029] In one possible implementation of the second aspect, determining the state of the charging relay based on the first diagnostic result and the second diagnostic result further includes:

[0030] When the vehicle is powered off, the first charging relay (303) is set to the off state and the second charging relay (304) is set to the off state. If the first diagnostic result is 0V and the second diagnostic result is the third preset value, then the first charging relay (303) and the second charging relay (304) are judged to be in normal state.

[0031] When the vehicle is powered off, the first charging relay (303) is set to the off state and the second charging relay (304) is set to the off state. If the first diagnostic result is the fourth preset value and the second diagnostic result is less than the fifth preset value, then the first charging relay (303) and the second charging relay (304) are judged to be in a fault state.

[0032] When the vehicle is powered off, the first charging relay (303) is set to the off state and the second charging relay (304) is set to the off state. If the first diagnostic result is 0V and the second diagnostic result is less than the fifth preset value, then the first charging relay (303) is judged to be in normal state and the second charging relay (304) is in fault state.

[0033] When the vehicle is powered off, the first charging relay (303) is set to the off state and the second charging relay (304) is set to the off state. If the first diagnostic result is the fifth preset value and the second diagnostic result is the third preset value, then the first charging relay (303) is determined to be in a fault state and the second charging relay (304) is in a normal state.

[0034] In one possible implementation of the second aspect, the first preset value is calculated based on the eighth resistance value, the ninth resistance value, and the voltage of the battery pack (100);

[0035] The second preset value is calculated based on the tenth resistance value, the eleventh resistance value, the twelfth resistance value, and the voltage of the second reference source (202);

[0036] The third preset value is calculated based on the tenth resistance value, the eleventh resistance value, and the voltage of the second reference source (202).

[0037] In one possible implementation of the second aspect, the fourth preset value is obtained based on the third voltage value and the fourth voltage value;

[0038] The fifth preset value is obtained based on the second and fourth voltage values, or calculated based on the eleventh resistor value in the fourth diagnostic circuit.

[0039] The technical solution of this invention has the following advantages:

[0040] The relay status detection circuit provided in this embodiment of the invention, by setting multiple diagnostic circuits in the vehicle charging circuit, realizes the status judgment of the positive charging relay and the negative charging relay by using the residual voltage of the discharge circuit of the vehicle load capacitor, reduces the influence of the residual voltage of the load capacitor on the judgment result, and improves the accuracy of the judgment.

[0041] The relay status detection method provided in this invention obtains a first diagnostic result based on a first voltage value in a first diagnostic circuit, a third voltage value obtained by a third diagnostic circuit, or a fourth voltage value obtained by a fourth diagnostic circuit; obtains a second diagnostic result based on the fourth voltage value obtained by a fourth diagnostic circuit or a second voltage value obtained by a second diagnostic circuit; and determines the status of the charging relay based on the first and second diagnostic results. By using different combinations of diagnostic circuits to determine the status of the positive charging relay and the negative charging relay, the method utilizes the residual voltage of the discharge circuit of the vehicle load capacitor to improve the accuracy of the determination results. Attached Figure Description

[0042] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0043] Figure 1 This is a schematic diagram of the circuit structure of the relay state detection circuit in an embodiment of the present invention;

[0044] Figure 2 This is a flowchart of the relay state detection method in an embodiment of the present invention;

[0045] Figure 3 This is a discharge circuit path diagram in the second combination of the relay state detection method in the emergency mode of the present invention embodiment;

[0046] Figure 4 This is a waveform diagram of the voltage collected by the first analog-to-digital converter in the second combination of the relay state detection method in the emergency mode of the embodiment of the present invention.

[0047] Figure 5 This is a current path analysis diagram at the second analog-to-digital converter in the second combination of the relay state detection method in the emergency mode of the embodiment of the present invention;

[0048] Figure 6 This is a discharge circuit path diagram in the third combination of the relay status detection method in the emergency mode of the present invention embodiment;

[0049] Figure 7 This is a current path analysis diagram at the second analog-to-digital converter in the third combination of the emergency mode of the relay state detection method in this embodiment of the invention;

[0050] The reference numerals in the accompanying drawings are as follows: 100 - Battery pack; 101 - Positive terminal of the battery pack; 102 - Negative terminal of the battery pack; 901 - Positive terminal of the vehicle's load interface; 902 - Negative terminal of the vehicle's load interface; 701 - Positive terminal of the vehicle's charging interface; 702 - Negative terminal of the vehicle's charging interface; 201 - First reference source; 202 - Second reference source; 401 - First resistor; 402 - Second resistor; 403 - Third resistor; 404 - Fourth resistor. Resistors; 405 - Fifth resistor; 406 - Sixth resistor; 407 - Seventh resistor; 408 - Eighth resistor; 409 - Ninth resistor; 410 - Tenth resistor; 411 - Eleventh resistor; 412 - Twelfth resistor; 500 - First capacitor; 800 - Diode; 601 - First analog-to-digital converter; 602 - Second analog-to-digital converter; 301 - First main relay; 302 - Second main relay; 303 - First charging relay; 304 - Second charging relay. Detailed Implementation

[0051] 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. 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.

[0052] In the description of this invention, it should be noted that the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0053] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, 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 mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can also refer to the internal connection of two components; it can be a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0054] The relay status detection circuit provided in this embodiment of the invention, such as Figure 1 As shown, the relay status detection circuit includes a battery pack (100), multiple relays, multiple diagnostic circuits, a first resistor (401), and a first capacitor (500).

[0055] Among them, the multiple relays include a first main relay (301), a second main relay (302), a first charging relay (303), and a second charging relay (304), and the multiple diagnostic circuits include a first diagnostic circuit, a second diagnostic circuit, a third diagnostic circuit, and a fourth diagnostic circuit.

[0056] The positive terminal of the battery pack (100) is connected to one end of the first main relay (301), and the negative terminal of the battery pack (100) is connected to one end of the second main relay (302);

[0057] One end of the first diagnostic circuit, one end of the first charging relay (303), one end of the first resistor (401), and one end of the first capacitor (500) are respectively connected to the other end of the first main relay (301);

[0058] The other end of the first diagnostic circuit, one end of the second charging relay (304), the other end of the first resistor (401), and the other end of the first capacitor (500) are respectively connected to the other end of the second main relay (302);

[0059] One end of the first charging relay (303) is connected to the second diagnostic circuit, the other end of the first charging relay (303) is connected to the third diagnostic circuit and the positive terminal (701) of the vehicle's charging interface, and the other end of the second charging relay (304) is connected to the fourth diagnostic circuit and the negative terminal (702) of the vehicle's charging interface.

[0060] In this embodiment, by setting up positive terminal relay sampling circuits and negative terminal relay sampling circuits, it is possible to determine whether there is a charging input voltage outside the vehicle when making a judgment on the charging relay. Specifically, as follows: Figure 1As shown, the positive terminal (901) and negative terminal (902) of the load interface of the vehicle are the load interfaces of the vehicle, which are generally connected to other high-voltage loads of the vehicle. The positive terminal (701) and negative terminal (702) of the charging interface of the vehicle are the charging interfaces of the vehicle, which are connected to external charging piles.

[0061] The positive terminal (101) of the battery pack is connected to one side of the first main relay (301), and the other side of the first main relay (301) is connected to one side of the first resistor (401), the first capacitor (500), and the first charging relay (303). The positive terminal (102) of the battery pack is connected to one side of the second main relay (302), and the other side of the second main relay (302) is connected to the other side of the first discharge resistor (401), the first capacitor (500), and the second charging relay (304).

[0062] It should be noted that the first main relay (301) refers to the main positive relay, the second main relay (302) is the main negative relay, the first charging relay (303) refers to the charging positive relay, and the second charging relay (304) refers to the charging negative relay. The charging relay is an electromagnetic control switch used to control the positive or negative connection in the charging circuit, and plays the role of connecting or disconnecting the charging positive line in the charging system. The battery pack (100) refers to the battery module. The first diagnostic circuit refers to the diagnostic circuit between the vehicle load positive terminal (901) and the vehicle load interface negative terminal (902). The second diagnostic circuit refers to the diagnostic circuit between the vehicle load interface positive terminal (901) and the battery pack negative terminal (102). The third diagnostic circuit refers to the diagnostic circuit between the vehicle charging interface positive terminal (701) and the battery pack negative terminal (102). The fourth diagnostic circuit refers to the diagnostic circuit between the vehicle charging interface negative terminal (702) and the battery pack negative terminal (102).

[0063] The relay status detection circuit provided in this embodiment of the invention, by setting multiple diagnostic circuits in the vehicle charging circuit, realizes the status judgment of the positive charging relay and the negative charging relay by using the residual voltage of the discharge circuit of the vehicle load capacitor, reduces the influence of the residual voltage of the load capacitor on the judgment result, and improves the accuracy of the judgment.

[0064] In one embodiment, the first diagnostic circuit includes a second resistor (402), a third resistor (403), a fourth resistor (404), a fifth resistor (405), and a first reference source (201).

[0065] Among them, one end of the second resistor (402) is connected to the other end of the first main relay (301), the other end of the second resistor (402) is connected to one end of the third resistor (403), the other end of the third resistor (403) is connected to the first reference source (201), and the second resistor (402) and the third resistor (403) are connected in series.

[0066] The other end of the fifth resistor (405) is connected to the other end of the second main relay (302), one end of the fifth resistor (405) is connected to one end of the fourth resistor (404), the other end of the fourth resistor (404) is connected to the first reference source (201), and the fifth resistor (405) and the fourth resistor (404) are connected in series.

[0067] In this embodiment, the diagnostic circuit of the positive terminal (901) and negative terminal (902) of the load interface of the vehicle includes a second resistor (402), a third resistor (403), a fourth resistor (404) and a fifth resistor (405). The second resistor (402) and the third resistor (403) are connected in series, and the fourth resistor (404) and the fifth resistor (405) are connected in series. The other end of the third resistor (403) is connected to one end of the first reference source (201), and the other end of the fourth resistor (404) is connected to the first reference source (201). One end of the second resistor (402) is connected to the other side of the positive main relay, and one end of the fifth resistor (405) is connected to the other side of the negative main relay.

[0068] It should be noted that the first reference source (201) is a reference voltage source used to provide a stable voltage reference.

[0069] In one embodiment, the second diagnostic circuit includes a sixth resistor (406) and a seventh resistor (407), which are connected in series.

[0070] In this embodiment, the diagnostic circuit between the positive terminal (901) of the load interface of the vehicle and the negative terminal (102) of the battery pack includes a sixth resistor (406) and a seventh resistor (407). The sixth resistor (406) and the seventh resistor (407) are connected in series and connected to one side of the first charging relay (303).

[0071] In one embodiment, the third diagnostic circuit includes an eighth resistor (408), a ninth resistor (409), and a first analog-to-digital converter (601), one end of which is connected to a node between the eighth resistor (408) and the ninth resistor (409), which are connected in series.

[0072] In this embodiment, the diagnostic circuit between the positive terminal (701) of the vehicle's charging interface and the negative terminal (102) of the battery pack includes an eighth resistor (408) and a ninth resistor (409). One end of the first analog-to-digital converter (601) is connected to the node between the eighth resistor (408) and the ninth resistor (409), and the eighth resistor (408) and the ninth resistor (409) are connected in series.

[0073] In one embodiment, the fourth diagnostic circuit includes a second reference source (202), a tenth resistor (410), an eleventh resistor (411), a twelfth resistor (412), a diode (800), and a second analog-to-digital converter (602).

[0074] One end of the tenth resistor (410) is connected to the positive terminal of the second reference source (202), and the other end of the tenth resistor (410) is connected to the input terminal of the second analog-to-digital converter (602).

[0075] One end of the eleventh resistor (411) is connected to the anode of the diode (800), the cathode of the diode (800) is connected to one end of the twelfth resistor (412), and the other end of the twelfth resistor (412) is connected to the other end of the second charging relay (304).

[0076] The tenth resistor (410) and the eleventh resistor (411) are connected in series, and the eleventh resistor (411) and the twelfth resistor (412) are connected in parallel.

[0077] In this embodiment, the diagnostic circuit between the negative terminal (702) of the vehicle's charging interface and the negative terminal (102) of the battery pack includes a first resistor (401), a diode (800), and a first resistor (401). One end of the first resistor (401) is connected to the positive terminal of the second reference source (202), and the other end of the first resistor (401) is connected to the input terminal of the second analog-to-digital converter (602). One end of the first resistor (401) is connected to the anode of the diode (800), and the cathode of the diode (800) is connected to the first resistor (401). The other end of the first resistor (401) is connected to the other side of the second charging relay (304). The first resistors (401) are connected in series and in parallel.

[0078] The relay status detection method provided in this embodiment of the invention, such as... Figure 2 The diagram shown is a flowchart of the relay state detection method provided in an embodiment of the present invention, including steps S201 to S202, each step of which is as follows:

[0079] S201: Based on the first voltage value in the first diagnostic circuit, the third voltage value obtained by the third diagnostic circuit, or the fourth voltage value obtained by the fourth diagnostic circuit, a first diagnostic result is obtained.

[0080] In this embodiment, under normal power-on / off mode or emergency power-off mode, when the vehicle is powered on or powered off, the first analog-to-digital converter (601) is used to collect the diagnostic circuit between the positive terminal (901) and the negative terminal (902) of the load interface of the vehicle, the diagnostic circuit between the positive terminal (701) of the charging interface of the vehicle and the negative terminal (102) of the battery pack, or the diagnostic circuit between the negative terminal (702) of the charging interface of the vehicle and the negative terminal (102) of the battery pack, and calculates the voltage to obtain the first diagnostic result.

[0081] S202: Based on the fourth voltage value obtained in the fourth diagnostic circuit or the second voltage value obtained in the second diagnostic circuit, a second diagnostic result is obtained.

[0082] In this embodiment, under normal power-on / off mode or emergency power-off mode, when the vehicle is powered on or powered off, the second analog-to-digital converter (602) is used to collect the voltage of the diagnostic circuit between the positive terminal (901) of the load interface of the vehicle and the negative terminal (102) of the battery pack or the voltage of the diagnostic circuit between the negative terminal (702) of the charging interface of the vehicle and the negative terminal (102) of the battery pack and calculate to obtain the second diagnostic result.

[0083] S203: Determine the status of the charging relay based on the first and second diagnostic results.

[0084] In this embodiment, the state of the charging relay is determined by using the voltages acquired by the first analog-to-digital converter (601) and the second analog-to-digital converter (602). Since the voltages acquired by the first analog-to-digital converter (601) and the second analog-to-digital converter (602) are different, the different states of the relay can be determined by the voltage states of the first analog-to-digital converter (601) and the second analog-to-digital converter (602).

[0085] In one embodiment, determining the state of the charging relay based on the first diagnostic result and the second diagnostic result includes:

[0086] When the vehicle is powered on, the first charging relay (303) is set to the closed state and the second charging relay (304) is set to the closed state. If the first diagnostic result is the first preset value and the second diagnostic result is the second preset value, then the first charging relay (303) and the second charging relay (304) are judged to be in normal state.

[0087] When the vehicle is powered on, the first charging relay (303) is set to the closed state and the second charging relay (304) is set to the closed state. If the first diagnostic result is 0V and the second diagnostic result is the third preset value, then the first charging relay (303) and the second charging relay (304) are judged to be in a fault state.

[0088] When the vehicle is powered on, the first charging relay (303) is set to the closed state and the second charging relay (304) is set to the closed state. If the first diagnostic result is the first preset value and the second diagnostic result is the third preset value, then the first charging relay (303) is judged to be in a normal state and the second charging relay (304) is in a fault state.

[0089] When the vehicle is powered on, the first charging relay (303) is set to the closed state and the second charging relay (304) is set to the closed state. If the first diagnostic result is 0V and the second diagnostic result is the second preset value, then the first charging relay (303) is judged to be in a fault state and the second charging relay (304) is in a normal state.

[0090] In this embodiment, under normal power-on / off mode, when the vehicle is powered on, the first charging relay (303) and the second charging relay (304) are both set to the closed state. If the first diagnostic result is a first preset value and the second diagnostic result is a second preset value, then the first charging relay (303) and the second charging relay (304) are determined to be in a normal state. If the first diagnostic result is 0V and the second diagnostic result is a third preset value, then the first charging relay (303) and the second charging relay (304) are determined to be in a fault state. If the first diagnostic result is a first preset value and the second diagnostic result is a third preset value, then the first charging relay (303) is determined to be in a normal state and the second charging relay (304) is in a fault state. If the first diagnostic result is 0V and the second diagnostic result is a second preset value, then the first charging relay (303) is determined to be in a fault state and the second charging relay (304) is in a normal state.

[0091] In one embodiment, determining the state of the charging relay based on the first diagnostic result and the second diagnostic result further includes:

[0092] When the vehicle is powered off, the first charging relay (303) is set to the off state and the second charging relay (304) is set to the off state. If the first diagnostic result is 0V and the second diagnostic result is the third preset value, then the first charging relay (303) and the second charging relay (304) are judged to be in normal state.

[0093] When the vehicle is powered off, the first charging relay (303) is set to the off state and the second charging relay (304) is set to the off state. If the first diagnostic result is the fourth preset value and the second diagnostic result is less than the fifth preset value, then the first charging relay (303) and the second charging relay (304) are judged to be in a fault state.

[0094] When the vehicle is powered off, the first charging relay (303) is set to the off state and the second charging relay (304) is set to the off state. If the first diagnostic result is 0V and the second diagnostic result is less than the fifth preset value, then the first charging relay (303) is judged to be in normal state and the second charging relay (304) is in fault state.

[0095] When the vehicle is powered off, the first charging relay (303) is set to the off state and the second charging relay (304) is set to the off state. If the first diagnostic result is the fifth preset value and the second diagnostic result is the third preset value, then the first charging relay (303) is determined to be in a fault state and the second charging relay (304) is in a normal state.

[0096] In this embodiment, in the emergency power-down mode, all relays are disconnected simultaneously. The first main relay (301) and the second main relay (302) can disconnect normally. The positive charging relay is disconnected, and the negative charging relay should also be disconnected. If the first diagnostic result is 0V and the second diagnostic result is the third preset value, then the first charging relay (303) and the second charging relay (304) are judged to be in a normal state. If the first diagnostic result is the fourth preset value and the second diagnostic result is less than the fifth preset value, then the first charging relay (303) and the second charging relay (304) are judged to be in a fault state. If the first diagnostic result is 0V and the second diagnostic result is less than the fifth preset value, then the first charging relay (303) is judged to be in a normal state and the second charging relay (304) is in a fault state. If the first diagnostic result is the fifth preset value and the second diagnostic result is the third preset value, then the first charging relay (303) is judged to be in a fault state and the second charging relay (304) is in a normal state.

[0097] In one embodiment, the first preset value is calculated based on the eighth resistance value, the ninth resistance value, and the voltage of the battery pack (100);

[0098] The second preset value is calculated based on the tenth resistance value, the eleventh resistance value, the twelfth resistance value, and the voltage of the second reference source (202);

[0099] The third preset value is calculated based on the tenth resistance value, the eleventh resistance value, and the voltage of the second reference source (202).

[0100] In this embodiment, the first preset value is calculated as follows:

[0101]

[0102] In the formula, Vb+b- is the voltage between the positive terminal (102) and the negative terminal (101) of the battery pack, R8 is the resistance value of the eighth resistor (408), R9 is the resistance value of the ninth resistor (409), and ADC1 is the first diagnostic result.

[0103] The formula for calculating the second preset value is:

[0104]

[0105] In the formula, Vref2 is the reference voltage of the second reference source (202), and R 11 R is the resistance value of the first resistor (401). 10 ADC1 represents the resistance value of the first resistor (401), and ADC2 represents the second diagnostic result.

[0106] The formula for calculating the third preset value is:

[0107]

[0108] In the formula, Vref2 is the reference voltage of the second reference source (202), and R 11 R is the resistance value of the first resistor (401). 10 The resistance value of the first resistor (401) is given, and ADC2 represents the second diagnostic result. R 12 The resistance value of the first resistor (401).

[0109] In one embodiment, the fourth preset value is obtained based on the third voltage value and the fourth voltage value;

[0110] The fifth preset value is obtained based on the second voltage value and the fourth voltage value, or calculated based on the eleventh resistor value in the fourth diagnostic circuit;

[0111] The fifth preset value is obtained based on the eleventh resistance value and the third voltage value.

[0112] In this embodiment, when the positive charging relay is unable to disconnect and the negative charging relay is unable to disconnect, the discharge circuit of the first capacitor (500) (hundred-uf level) of the vehicle is as follows: Figure 3 The arrow path shown indicates that the voltage waveform acquired by the first analog-to-digital converter (601) is approximately the discharge curve of the first capacitor (500) against the first resistor (401), i.e., the fourth preset value, as shown. Figure 4 As shown. For the reasonable detection time of the voltage of the first analog-to-digital converter (601), the discharge time of C1 τ = 3*R1*C1 can be referenced.

[0113] At this time, the node current path of the second analog-to-digital converter (602) is as follows: Figure 5 As shown, the formula for calculating the fifth preset value is:

[0114] ADC2 = -R 11 *IR 11

[0115] In the formula, ADC2 represents the second diagnostic result, and R... 11 Let I be the resistance of the first resistor (401), I be the current, and IR be the resistance of the first resistor (401). 11 After being limited by the bridge arm resistor, the current is only in the μA range, so the voltage sampled by the second analog-to-digital converter (602) is close to 0V.

[0116] When the positive charging relay is disconnected and the negative charging relay cannot be disconnected, the discharge circuit is as follows: Figure 6 As shown, the voltage waveform collected by the first analog-to-digital converter (601) at this time is approximately the discharge curve of the first capacitor (500) to R1. The voltage detection time of the first analog-to-digital converter (601) can be referenced to the discharge time of C1, τ = 3 * R1 * C1.

[0117] For the current path analysis of the second analog-to-digital converter (602) as follows: Figure 7 As shown, at this time ADC2 = -R 11 *IR 11 Since IR11 is limited to the uA level by the bridge arm resistor, the voltage sampled by the second analog-to-digital converter (602) is close to 0V.

[0118] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0119] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A relay state detection method, applied to a relay state detection circuit, characterized in that, The relay status detection circuit includes a battery pack (100), multiple relays, multiple diagnostic circuits, a first resistor (401) and a first capacitor (500). The multiple relays include a first main relay (301), a second main relay (302), a first charging relay (303) and a second charging relay (304). The multiple diagnostic circuits include a first diagnostic circuit, a third diagnostic circuit and a fourth diagnostic circuit. The positive terminal of the battery pack (100) is connected to one end of the first main relay (301), the negative terminal of the battery pack (100) is connected to one end of the second main relay (302), and one end of the first diagnostic circuit, one end of the first charging relay (303), one end of the first resistor (401), and one end of the first capacitor (500) are respectively connected to the other end of the first main relay (301). The other end of the first diagnostic circuit, one end of the second charging relay (304), the other end of the first resistor (401), and the other end of the first capacitor (500) are respectively connected to the other end of the second main relay (302); The other end of the first charging relay (303) is connected to the positive terminal (701) of the third diagnostic circuit and the vehicle's charging interface, and the other end of the second charging relay (304) is connected to the negative terminal (702) of the fourth diagnostic circuit and the vehicle's charging interface. The first diagnostic circuit includes a second resistor (402), a third resistor (403), a fourth resistor (404), a fifth resistor (405), and a first reference source (201). One end of the second resistor (402) is connected to the other end of the first main relay (301), and the other end of the second resistor (402) is connected to one end of the third resistor (403). The other end of the third resistor (403) is connected to the first reference source (201), and the second resistor (402) and the third resistor (403) are connected in series. The other end of the fifth resistor (405) is connected to the other end of the second main relay (302), and one end of the fifth resistor (405) is connected to one end of the fourth resistor (404). The other end of the fourth resistor (404) is connected to the first reference source (201), and the fifth resistor (405) and the fourth resistor (404) are connected in series. The diagnostic circuit further includes a second diagnostic circuit, which is connected to the other end of the first charging relay (303). The second diagnostic circuit includes a sixth resistor (406) and a seventh resistor (407), which are connected in series. The third diagnostic circuit includes an eighth resistor (408), a ninth resistor (409), and a first analog-to-digital converter (601), wherein one end of the first analog-to-digital converter (601) is connected to a node between the eighth resistor (408) and the ninth resistor (409), and the eighth resistor (408) and the ninth resistor (409) are connected in series. The fourth diagnostic circuit includes a second reference source (202), a tenth resistor (410), an eleventh resistor (411), a twelfth resistor (412), a diode (800), and a second analog-to-digital converter (602). One end of the tenth resistor (410) is connected to the positive terminal of the second reference source (202), and the other end of the tenth resistor (410) is connected to the input terminal of the second analog-to-digital converter (602). One end of the eleventh resistor (411) is connected to the anode of the diode (800), and the cathode of the diode (800) is connected to one end of the twelfth resistor (412). The other end of the twelfth resistor (412) is connected to the other end of the second charging relay (304). The tenth resistor (410) and the eleventh resistor (411) are connected in series, and the eleventh resistor (411) and the twelfth resistor (412) are connected in parallel. The relay status detection method includes: The first diagnostic result is obtained by using the voltage collected by the first analog-to-digital converter (601) when the vehicle is powered on or off; A second diagnostic result is obtained by using the voltage collected by the second analog-to-digital converter (602) when the vehicle is powered on or off; The state of the charging relay is determined based on the first diagnostic result and the second diagnostic result.

2. The relay state detection method as described in claim 1, characterized in that, The step of determining the state of the charging relay based on the first diagnostic result and the second diagnostic result includes: When the vehicle is powered on, the first charging relay (303) is set to the closed state and the second charging relay (304) is set to the closed state. If the first diagnostic result is the first preset value and the second diagnostic result is the second preset value, then the first charging relay (303) and the second charging relay (304) are judged to be in normal state. When the vehicle is powered on, the first charging relay (303) is set to the closed state and the second charging relay (304) is set to the closed state. If the first diagnostic result is 0V and the second diagnostic result is the third preset value, then the first charging relay (303) and the second charging relay (304) are determined to be in a fault state. When the vehicle is powered on, the first charging relay (303) is set to the closed state and the second charging relay (304) is set to the closed state. If the first diagnostic result is the first preset value and the second diagnostic result is the third preset value, then the first charging relay (303) is determined to be in a normal state and the second charging relay (304) is in a fault state. When the vehicle is powered on, the first charging relay (303) is set to the closed state and the second charging relay (304) is set to the closed state. If the first diagnostic result is 0V and the second diagnostic result is the second preset value, then the first charging relay (303) is determined to be in a fault state and the second charging relay (304) is in a normal state.

3. The relay state detection method as described in claim 2, characterized in that, The step of determining the state of the charging relay based on the first diagnostic result and the second diagnostic result further includes: When the vehicle is powered off, the first charging relay (303) is set to the off state and the second charging relay (304) is set to the off state. If the first diagnostic result is 0V and the second diagnostic result is the third preset value, then the first charging relay (303) and the second charging relay (304) are judged to be in normal state. When the vehicle is powered off, the first charging relay (303) is set to the off state and the second charging relay (304) is set to the off state. If the first diagnostic result is the fourth preset value and the second diagnostic result is less than the fifth preset value, then the first charging relay (303) and the second charging relay (304) are determined to be in a fault state. When the vehicle is powered off, the first charging relay (303) is set to the off state and the second charging relay (304) is set to the off state. If the first diagnostic result is 0V and the second diagnostic result is less than the fifth preset value, then the first charging relay (303) is judged to be in a normal state and the second charging relay (304) is in a fault state. When the vehicle is powered off, the first charging relay (303) is set to the off state and the second charging relay (304) is set to the off state. If the first diagnostic result is the fifth preset value and the second diagnostic result is the third preset value, then the first charging relay (303) is determined to be in a fault state and the second charging relay (304) is in a normal state.

4. The relay state detection method as described in claim 3, characterized in that, The first preset value is calculated based on the eighth resistance value, the ninth resistance value, and the voltage of the battery pack (100); The second preset value is calculated based on the tenth resistance value, the eleventh resistance value, and the voltage of the second reference source (202); The third preset value is calculated based on the tenth resistance value, the eleventh resistance value, the twelfth resistance value, and the voltage of the second reference source (202).

5. The relay status detection method as described in claim 4, characterized in that, The fourth preset value is determined based on the discharge curve of the first capacitor (500) to the first resistor (401); The fifth preset value is calculated based on the eleventh resistance value.

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