Relay state detection circuit and detection method

Abstract

The invention discloses a relay state detection circuit and method, and the circuit comprises a battery pack, a plurality of relays, a plurality of diagnosis circuits, a first resistor and a first capacitor, the positive electrode of the battery pack is connected with one end of a first main relay, and the negative electrode of the battery pack is connected with one end of a second main relay; one ends of the first diagnosis circuit, the first charging relay, the first resistor and the first capacitor are respectively connected with the other end of the first main relay; one end of the second charging relay, the first diagnosis circuit, the first resistor and the other end of the first capacitor are respectively connected with the other end of the second main relay; the other end of the first charging relay is connected with the third diagnosis circuit and the positive electrode of the charging interface. The other end of the second charging relay is connected with the fourth diagnosis circuit and the negative electrode of the charging interface. According to the method, the state judgment of the charging positive relay and the charging negative relay is realized by utilizing the residual voltage of the discharging loop of the whole vehicle load capacitor.

Description

Technical Field

[0001] The present invention relates to the technical field of relay detection, and in particular to a relay state detection circuit and a detection method. Background Art

[0002] With the continuous development of the new energy industry, the safety performance requirements of electric vehicles are also gradually increasing. The safety performance of the high-voltage system of electric vehicles is becoming more and more important. As a switch for the battery pack to supply power to the external load, the reliability of the high-voltage DC contactor becomes crucial; for the state detection of the contactor, such as normal operation and failure state (unable to attract, unable to disconnect), the controller must make accurate judgments and be able to promptly feedback the state of the contactor to the driver to reduce safety risks. The traditional voltage physical quantity measurement method determines the state of the charging relay. The interference term is the residual voltage of the load capacitor, which will affect the accuracy of the acquisition. Summary of the invention

[0003] In order to solve the above technical problems, the embodiments of the present invention provide a relay state detection circuit and a detection method, which solve the problem in the prior art that the state of the charging relay is inaccurately determined due to interference items.

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

[0005] The plurality of 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 plurality of diagnostic circuits include a first diagnostic circuit, a third diagnostic circuit and a fourth diagnostic circuit;

[0006] The positive electrode of the battery pack (100) is connected to one end of the first main relay (301), and the negative electrode 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 third diagnostic circuit and the positive pole (701) of the charging interface of the whole vehicle, and the other end of the second charging relay (304) is connected to the fourth diagnostic circuit and the negative pole (702) of the charging interface of the whole vehicle.

[0010] In a possible implementation manner 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] 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 a possible implementation manner of the first aspect, the diagnostic circuit further includes a second diagnostic circuit, the second diagnostic circuit being 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), and the sixth resistor (406) and the seventh resistor (407) are connected in series.

[0015] In a 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 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.

[0016] In a possible implementation manner 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 electrode of the second reference source (202), and the other end of the tenth resistor (410) is connected to the input end 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] In order to solve the same technical problem, a second aspect of an embodiment of the present invention provides a relay state detection method, the method comprising:

[0021] Obtaining a first diagnostic result based on a first voltage value in the first diagnostic circuit, a third voltage value obtained by the third diagnostic circuit, or a fourth voltage value obtained by the fourth diagnostic circuit;

[0022] Obtaining a second diagnostic result based on a fourth voltage value obtained in the fourth diagnostic circuit or a second voltage value obtained in the second diagnostic circuit;

[0023] The state of the charging relay is determined according to the first diagnosis result and the second diagnosis result.

[0024] In a possible implementation manner of the second aspect, judging the state of the charging relay according to 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 a closed state, and the second charging relay (304) is set to a 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 judged to be in a normal state;

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

[0029] In a possible implementation manner of the second aspect, judging the state of the charging relay according to 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 a disconnected state, and the second charging relay (304) is set to a disconnected state; if the first diagnostic result is 0V and the second diagnostic result is a third preset value, the first charging relay (303) and the second charging relay (304) are judged to be in a normal state;

[0031] When the vehicle is powered off, the first charging relay (303) is set to a disconnected state, and the second charging relay (304) is set to a disconnected state; if the first diagnostic result is a fourth preset value, and the second diagnostic result is less than a 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 a disconnected state, and the second charging relay (304) is set to a disconnected state; if the first diagnostic result is 0V and the second diagnostic result is less than a fifth preset value, it is determined that the first charging relay (303) is in a normal state and the second charging relay (304) is in a fault state;

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

[0034] In a possible implementation manner 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 standard 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 standard source (202).

[0037] In a possible implementation manner of the second aspect, the fourth preset value is obtained according to the third voltage value and the fourth voltage value;

[0038] The fifth preset value is obtained according to the second voltage value and the fourth voltage value, or is calculated according to the eleventh resistance value in the fourth diagnostic circuit.

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

[0040] The relay state detection circuit provided in the embodiment of the present invention realizes the state judgment of the charging positive relay and the charging negative relay by using the residual voltage of the discharge circuit of the load capacitor of the whole vehicle, by setting multiple diagnostic circuits in the automobile charging circuit, thereby reducing the influence of the interference term of the residual voltage of the load capacitor on the judgment result and improving the accuracy of the judgment.

[0041] The relay state detection method provided by the embodiment of the present invention obtains a first diagnostic result 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; obtains a second diagnostic result based on the fourth voltage value obtained in the fourth diagnostic circuit or the second voltage value obtained by the second diagnostic circuit; judges the state of the charging relay according to the first diagnostic result and the second diagnostic result, and judges the state of the charging positive relay and the charging negative relay through different diagnostic circuit combinations, thereby realizing the use of the residual voltage of the discharge circuit of the vehicle load capacitor to improve the accuracy of the judgment result. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 Schematic diagram of the circuit structure of the relay state detection circuit in an embodiment of the present invention;

[0044] Figure 2 Flow chart of a detection method of a relay state detection method in an embodiment of the present invention;

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

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

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

[0048] Figure 6 A discharge circuit path diagram in the third combination in the emergency mode of the relay state detection method in an embodiment of the present invention;

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

[0050] The reference numerals of the drawings in the specification are as follows: 100-battery pack; 101-positive electrode of the battery pack; 102-negative electrode of the battery pack; 901-positive electrode of the load interface of the whole vehicle; 902-negative electrode of the load interface of the whole vehicle; 701-positive electrode of the charging interface of the whole vehicle; 702-negative electrode of the charging interface of the whole vehicle; 201-first reference source; 202-second reference source; 401-first resistor; 402-second resistor; 403-third resistor; 404-fourth Resistor; 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 DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0053] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense, 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, or it can be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0054] The relay state detection circuit provided by the embodiment of the present invention is as follows: Figure 1 As shown, the relay state detection circuit comprises a battery pack (100), a plurality of relays, a plurality of diagnostic circuits, a first resistor (401) and a first capacitor (500),

[0055] The plurality of 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 plurality of diagnostic circuits include a first diagnostic circuit, a second diagnostic circuit, a third diagnostic circuit and a fourth diagnostic circuit;

[0056] The positive electrode of the battery pack (100) is connected to one end of the first main relay (301), and the negative electrode 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 pole (701) of the charging interface of the whole vehicle, and the other end of the second charging relay (304) is connected to the fourth diagnostic circuit and the negative pole (702) of the charging interface of the whole vehicle.

[0060] In this embodiment, by setting the positive terminal relay sampling circuit and the negative terminal relay sampling circuit, it is possible to determine whether there is a charging input voltage outside the vehicle and to perform a judgment on the charging relay. Specifically, Figure 1As shown, the positive pole (901) of the load interface of the whole vehicle and the negative pole (902) of the load interface are the load interface of the whole vehicle, which are generally connected to other high-voltage loads of the whole vehicle, and the positive pole (701) of the charging interface of the whole vehicle and the negative pole (702) of the charging interface of the whole vehicle are the charging interface of the whole vehicle, which are connected to an external charging pile.

[0061] The positive electrode (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 electrode (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 resistor (401), the first capacitor (500) and the second charging relay (304) of the vehicle discharge.

[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, wherein the charging relay is an electromagnetic control switch used to control the positive or negative connection in the charging circuit, and plays a role in connecting or disconnecting the charging positive line in the charging system. The battery pack (100) refers to a battery module. The first diagnostic circuit refers to the diagnostic circuit between the positive pole (901) of the vehicle load and the negative pole (902) of the vehicle load interface, the second diagnostic circuit refers to the diagnostic circuit between the positive pole (901) of the vehicle load interface and the negative pole (102) of the battery pack, the third diagnostic circuit refers to the diagnostic circuit between the positive pole (701) of the vehicle charging interface and the negative pole (102) of the battery pack, and the fourth diagnostic circuit refers to the diagnostic circuit between the negative pole (702) of the vehicle charging interface and the negative pole (102) of the battery pack.

[0063] The relay state detection circuit provided in the embodiment of the present invention realizes the state judgment of the charging positive relay and the charging negative relay by using the residual voltage of the discharge circuit of the load capacitor of the whole vehicle, by setting multiple diagnostic circuits in the automobile charging circuit, thereby reducing the influence of the interference term of the residual voltage of the load capacitor on the judgment result and improving 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] 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 electrode (901) of the load interface of the whole vehicle and the negative electrode (902) of the load interface of the whole 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, 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), 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, which is 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), and the sixth resistor (406) and the seventh resistor (407) are connected in series.

[0070] In this embodiment, the diagnostic circuit between the positive electrode (901) of the load interface of the whole vehicle and the negative electrode (102) of the battery pack includes a sixth resistor (406) and a seventh resistor (407), and 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 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.

[0072] In this embodiment, the diagnostic circuit between the positive electrode (701) of the charging interface of the whole vehicle and the negative electrode (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 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.

[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 electrode of the second reference source (202), and the other end of the tenth resistor (410) is connected to the input end 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 electrode (702) of the charging interface of the whole vehicle and the negative electrode (102) of the battery pack includes a first resistor (401), a first resistor (401), a diode (800) and a first resistor (401), one end of the first resistor (401) is connected to the positive electrode of the second reference source (202), and the other end of the first resistor (401) is connected to the input end of the second analog-to-digital converter (602); one end of the first resistor (401) is connected to the anode of the diode (800), the cathode of the diode (800) is connected to the first resistor (401), and the other end of the first resistor (401) is connected to the other side of the second charging relay (304). The first resistor (401) is connected in series with the first resistor (401), and the first resistor (401) is connected in parallel with the first resistor (401).

[0078] The relay state detection method provided by the embodiment of the present invention is as follows: Figure 2 As shown, it is a flow chart of the relay state detection method provided by an embodiment of the present invention, including steps S201 to S202, and each step is specifically as follows:

[0079] S201: Obtain 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.

[0080] In this embodiment, in the normal power-on and power-off mode or the 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 voltage in the diagnostic circuit of the positive pole (901) of the load interface of the whole vehicle and the negative pole (902) of the load interface of the whole vehicle, the diagnostic circuit between the positive pole (701) of the charging interface of the whole vehicle and the negative pole (102) of the battery pack, or the diagnostic circuit between the negative pole (702) of the charging interface of the whole vehicle and the negative pole (102) of the battery pack to obtain a first diagnostic result.

[0081] S202: Obtain a second diagnostic result based on a fourth voltage value obtained by the fourth diagnostic circuit or a second voltage value obtained by the second diagnostic circuit.

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

[0083] S203: Determine the state of the charging relay according to the first diagnosis result and the second diagnosis result.

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

[0085] In one embodiment, judging the state of the charging relay according to the first diagnosis result and the second diagnosis result includes:

[0086] When the vehicle is powered on, the first charging relay (303) is set to a closed state, and the second charging relay (304) is set to a 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 judged to be in a normal state;

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

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

[0091] In one embodiment, judging the state of the charging relay according to the first diagnosis result and the second diagnosis result further includes:

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

[0093] When the vehicle is powered off, the first charging relay (303) is set to a disconnected state, and the second charging relay (304) is set to a disconnected state; if the first diagnostic result is a fourth preset value, and the second diagnostic result is less than a 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 a disconnected state, and the second charging relay (304) is set to a disconnected state; if the first diagnostic result is 0V and the second diagnostic result is less than a fifth preset value, it is determined that the first charging relay (303) is in a normal state and the second charging relay (304) is in a fault state;

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

[0096] In the present embodiment, in the emergency power-off mode, all relays are disconnected simultaneously, the first main relay (301) and the second main relay (302) can be disconnected normally, the charging positive relay is disconnected, and the charging negative relay should also be disconnected. If the first diagnostic result is 0V and the second diagnostic result is the third preset value, 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, 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, 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, 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 standard 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 standard source (202).

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

[0101]

[0102] Wherein, Vb+b- is the voltage between the positive electrode (102) and the negative electrode (101) of the battery pack, R 8 is the resistance value of the eighth resistor (408), R 9 is the resistance value of the ninth resistor (409), ADC 1 This is the first diagnosis result.

[0103] The calculation formula of the second preset value is:

[0104]

[0105] Wherein, Vref2 is the reference voltage of the second reference source (202), R 11 is the resistance value of the first resistor (401), R 10 is the resistance value of the first resistor (401), ADC 2 This is the second diagnosis result.

[0106] The calculation formula of the third preset value is:

[0107]

[0108] Wherein, Vref2 is the reference voltage of the second reference source (202), R 11 is the resistance value of the first resistor (401), R 10 is the resistance value of the first resistor (401), ADC 2 is the second diagnosis result, R 12 is the resistance value of the first resistor (401).

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

[0110] The fifth preset value is obtained according to the second voltage value and the fourth voltage value, or is calculated according to the eleventh resistance value in the fourth diagnostic circuit;

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

[0112] In this embodiment, when the charging positive relay cannot be disconnected and the charging negative relay cannot be disconnected, the first capacitor (500) (hundred uf level) of the vehicle discharge circuit is as follows: Figure 3 The arrow path shown in FIG. 1 shows, at this time, the voltage waveform collected by the first analog-to-digital converter (601) is approximately the discharge curve of the first capacitor (500) to the first resistor (401), that is, the fourth preset value, such as Figure 4As shown, the reasonable detection time of the voltage of the first analog-to-digital converter (601) can refer to the discharge time τ of C1 = 3*R1*C1.

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

[0114] ADC 2 =-R 11 *IR 11

[0115] Where, ADC 2 is the second diagnosis result, R 11 is the resistance of the first resistor (401), I is the current, IR 11 After being limited by the bridge arm resistor, the current is only at the uA level, 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, at this time, the voltage waveform collected on the first analog-to-digital converter (601) 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 refer to the discharge time τ=3*R1*C1 of C1.

[0117] The current path analysis for the second analog-to-digital converter (602) is as follows: Figure 7 As shown, at this time ADC 2 =-R 11 *IR 11 Since IR11 is limited by the bridge arm resistor to only uA level, the voltage sampled by the second analog-to-digital converter (602) is close to 0V.

[0118] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, 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 solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A relay state detection circuit, characterized in that: The invention comprises a battery pack (100), a plurality of relays, a plurality of diagnostic circuits, a first resistor (401) and a first capacitor (500), The plurality of 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 plurality of diagnostic circuits include a first diagnostic circuit, a third diagnostic circuit and a fourth diagnostic circuit; The positive electrode of the battery pack (100) is connected to one end of the first main relay (301), and the negative electrode of the battery pack (100) is connected to one end of the second main relay (302); 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 third diagnostic circuit and the positive pole (701) of the charging interface of the whole vehicle, and the other end of the second charging relay (304) is connected to the fourth diagnostic circuit and the negative pole (702) of the charging interface of the whole vehicle.

2. The relay state detection circuit according to claim 1, characterized in that: The first diagnostic circuit comprises a second resistor (402), a third resistor (403), a fourth resistor (404), a fifth resistor (405) and a first reference source (201). wherein 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; 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) is connected in series with the fourth resistor (404).

3. The relay state detection circuit according to claim 1, characterized in that: The diagnostic circuit further comprises a second diagnostic circuit, wherein the second diagnostic circuit 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), wherein the sixth resistor (406) and the seventh resistor (407) are connected in series.

4. The relay state detection circuit according to claim 1, characterized in that: The third diagnostic circuit comprises 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.

5. The relay state detection circuit according to claim 1, characterized in that: The fourth diagnostic circuit comprises 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). Wherein, one end of the tenth resistor (410) is connected to the positive electrode of the second reference standard source (202), and the other end of the tenth resistor (410) is connected to the input end of the second analog-to-digital converter (602); 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); The tenth resistor (410) is connected in series with the eleventh resistor (411), and the eleventh resistor (411) is connected in parallel with the twelfth resistor (412).

6. A relay state detection method, characterized in that: The method is implemented by a relay state detection circuit as claimed in any one of claims 1 to 5, comprising: Obtaining a first diagnostic result based on a first voltage value in the first diagnostic circuit, a third voltage value obtained by the third diagnostic circuit, or a fourth voltage value obtained by the fourth diagnostic circuit; Obtaining a second diagnostic result based on a fourth voltage value obtained in the fourth diagnostic circuit or a second voltage value obtained in the second diagnostic circuit; The state of the charging relay is determined according to the first diagnosis result and the second diagnosis result.

7. The relay state detection method according to claim 6, characterized in that: The determining the state of the charging relay according to the first diagnostic result and the second diagnostic result includes: When the vehicle is powered on, the first charging relay (303) is set to a closed state, and the second charging relay (304) is set to a 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 judged to be in a normal state; When the vehicle is powered on, the first charging relay (303) is set to a closed state, and the second charging relay (304) is set to a closed state; if the first diagnostic result is 0V and the second diagnostic result is a third preset value, the first charging relay (303) and the second charging relay (304) are judged to be in a fault state; When the vehicle is powered on, the first charging relay (303) is set to a closed state, and the second charging relay (304) is set to a closed state; if the first diagnostic result is a first preset value, and the second diagnostic result is a third preset value, then it is determined that the first charging relay (303) is 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 a closed state, and the second charging relay (304) is set to a closed state. If the first diagnostic result is 0V and the second diagnostic result is a second preset value, it is determined that the first charging relay (303) is in a fault state and the second charging relay (304) is in a normal state.

8. The relay state detection method according to claim 6, characterized in that: The step of determining the state of the charging relay according to 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 a disconnected state, and the second charging relay (304) is set to a disconnected 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 judged to be in a normal state; When the vehicle is powered off, the first charging relay (303) is set to a disconnected state, and the second charging relay (304) is set to a disconnected state; if the first diagnostic result is a fourth preset value, and the second diagnostic result is less than a fifth preset value, then the first charging relay (303) and the second charging relay (304) are judged to be in a fault state; When the vehicle is powered off, the first charging relay (303) is set to a disconnected state, and the second charging relay (304) is set to a disconnected state; if the first diagnostic result is 0V and the second diagnostic result is less than a fifth preset value, it is determined that the first charging relay (303) is 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 a disconnected state, and the second charging relay (304) is set to a disconnected state. If the first diagnostic result is a fifth preset value and the second diagnostic result is a third preset value, it is determined that the first charging relay (303) is in a fault state and the second charging relay (304) is in a normal state.

9. The relay state detection method according to claim 6, 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, the twelfth resistance value and the voltage of the second reference standard source (202); The third preset value is calculated based on the tenth resistance value, the eleventh resistance value and the voltage of the second reference standard source (202).

10. The relay state detection method according to any one of claims 6 or 8, characterized in that: The fourth preset value is obtained according to the third voltage value and the fourth voltage value; The fifth preset value is obtained according to the second voltage value and the fourth voltage value, or is calculated according to an eleventh resistance value in the fourth diagnostic circuit.

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