Fault diagnosis circuit and method for direct-current high-voltage relay

Abstract

The invention provides a fault diagnosis circuit and method for a direct-current high-voltage relay. The fault diagnosis circuit comprises a single-chip microcomputer controller, a first detection circuit and a second detection circuit. According to the invention, the single-chip microcomputer controller controls the on-off of the main positive relay, the main negative relay and the pre-charging relay and sends a first control signal and a second control signal to control the first detection circuit and the second detection circuit to detect the main positive relay and the main negative relay and obtain a feedback signal; the feedback signals are sent to the single-chip microcomputer controller for fault state judgment, and fault state detection results of the main positive relay and the main negative relay are obtained; compared with the prior art, adhesion type faults can be judged, the fault that the relay cannot be closed can be judged, the reliability of fault state diagnosis of the relay is improved, and therefore safety accidents are effectively prevented.

Description

Technical Field

[0001] The invention relates to the technical field of electric vehicle relay fault diagnosis, and in particular to a fault diagnosis circuit and method for a DC high voltage relay. Background Art

[0002] With the development of new energy vehicle technology, electric vehicles have become an important direction for the development of automobile technology. In electric vehicles, the safety performance of the power battery control system is the most important content of the performance of the whole vehicle. In the battery pack management system, the battery control unit is the core of the power battery control system, and the DC high-voltage relay is a key switching device. When the relay fails and is not controlled, there will be great safety risks. Therefore, in the high-voltage battery pack management system, the relay must be able to work stably for a long time; so the battery pack management system for electric vehicles not only needs to have the basic function of controlling the opening and closing of the high-voltage relay, but also has the relay fault diagnosis function.

[0003] There are currently two solutions used in energy storage products and automotive power battery products:

[0004] The first is to use a DC high-voltage relay with auxiliary contacts. This type of relay uses inert gas to control the on and off of the relay, and contains a mechanical linkage device between the auxiliary contact and the main contact. When the main contact is closed or opened, the auxiliary contact is also closed or opened at the same time; the microcontroller determines the switching state of the main contact by detecting the switching value of the auxiliary contact; however, the cost of the relay selected in this solution is high, the relay is large in size, and the fault type cannot be accurately diagnosed;

[0005] The second method is to sample the voltage at the output end of the battery management system, that is, the output end of the relay, and determine whether it is sticking by sampling the voltage when the relay is not closed. However, this solution cannot determine the fault condition of a single relay, but can only determine the condition where both relays are sticking. Summary of the invention

[0006] The present invention provides a fault diagnosis circuit and method for a DC high voltage relay, the purpose of which is to improve the reliability of fault diagnosis.

[0007] In order to achieve the above object, the present invention provides a fault diagnosis circuit of a DC high voltage relay, the DC high voltage relay includes a main positive relay, a main negative relay, a pre-charge relay, and a battery pack, and the fault diagnosis circuit includes:

[0008] A single chip microcomputer controller, a first detection circuit and a second detection circuit;

[0009] The output end of the single-chip microcomputer controller is respectively connected to the control end of the main positive relay, the control end of the main negative relay, the control end of the pre-charge relay, the control end of the first detection circuit, and the control end of the second detection circuit;

[0010] The first end of the first detection module is respectively connected to the second end of the main positive relay, the second end of the pre-charge relay, and the positive electrode of the output end of the DC high-voltage relay;

[0011] The first end of the second detection module is respectively connected to the first end of the main positive relay, the second end of the pre-charge relay, and the positive electrode of the battery pack;

[0012] The second end of the first detection module is connected to the first end of the main negative relay and the negative electrode of the battery pack respectively;

[0013] The second end of the second detection module is connected to the second end of the main negative relay and the negative pole of the output end of the DC high-voltage relay respectively;

[0014] The third end of the first detection module and the third end of the second detection module are both connected to the input end of the single-chip microcomputer controller;

[0015] The single-chip microcomputer controller controls the main positive relay, main negative relay, and pre-charge relay on and off;

[0016] The single-chip microcomputer controller sends a first control signal and a second control signal to control the first detection circuit and the second detection circuit to detect the main positive relay and the main negative relay, receives feedback signals sent by the first detection circuit and the second detection circuit after detection, and performs fault status judgment based on the feedback signals to obtain the fault status detection results of the main positive relay and the main negative relay.

[0017] Further, the first detection circuit includes a first voltage dividing module, a first relay, a first photocoupler, a first resistor R1, a first NMOS tube, and a second resistor;

[0018] The second detection circuit includes a second voltage dividing module, a second relay, a second photoelectric coupler, a third resistor, a second NMOS tube, and a fourth resistor;

[0019] The first end of the first voltage divider module is respectively connected to the second end of the main positive relay, the second end of the pre-charge relay, and the positive electrode of the DC high-voltage relay output end, the second end of the first voltage divider module is connected to the first contact end of the first relay, the second contact end of the first relay is connected to the first end of the first photoelectric coupler, the second end of the first photoelectric coupler is connected to the negative electrode of the battery pack, the second end of the first photoelectric coupler is connected to the second end of the second photoelectric coupler through the main negative relay, the third end of the first photoelectric coupler is respectively connected to the signal transmission end of the single-chip controller and the first end of the first resistor R1, the fourth end of the first photoelectric coupler is connected to the system power supply, and the system power supply is connected to the second end of the first resistor R1 and grounded;

[0020] The first coil end of the first relay is connected to the power supply end, the second coil end of the first relay is connected to the drain of the first NMOS tube, the gate of the first NMOS tube is connected to the signal transmission end of the single-chip controller through the second resistor, and the source of the first NMOS tube is grounded;

[0021] The first end of the second voltage divider module is respectively connected to the first end of the main positive relay, the second end of the pre-charge relay, and the positive electrode of the battery pack, the second end of the first voltage divider module is connected to the first contact end of the second relay, the second contact end of the second relay is connected to the first end of the second photoelectric coupler, the second end of the second photoelectric coupler is connected to the negative electrode of the output end of the DC high-voltage relay, the third end of the second photoelectric coupler is respectively connected to the signal transmission end of the single-chip controller and the first end of the third resistor, the fourth end of the second photoelectric coupler is connected to the system power supply, and the system power supply is connected to the second end of the third resistor and grounded;

[0022] The first coil end of the second relay is connected to the power supply end, the second coil end of the second relay is connected to the drain of the second NMOS tube, the gate of the second NMOS tube is connected to the signal transmission end of the microcontroller controller through the fourth resistor, and the source of the second NMOS tube is grounded.

[0023] Further, the first detection circuit also includes: a first Schottky diode, a first Zener diode, and a first freewheeling diode;

[0024] The second detection circuit also includes: a second Schottky diode, a second Zener diode, and a second freewheeling diode;

[0025] An anode of the first Schottky diode is connected to the second end of the first voltage divider module, and a cathode of the first Schottky diode is connected to the first contact end of the first relay;

[0026] The cathode of the first Zener diode is connected to the second contact terminal of the first relay, and the anode of the first Zener diode is connected to the first terminal of the first photocoupler;

[0027] The cathode of the first freewheeling diode is respectively connected to the first coil end and the power supply end of the first relay, and the anode of the first freewheeling diode is respectively connected to the second coil end of the first relay, the drain of the first NMOS tube, and the power supply end;

[0028] An anode of the second Schottky diode is connected to the second end of the second voltage divider module, and a cathode of the second Schottky diode is connected to the first contact end of the second relay;

[0029] The cathode of the second Zener diode is connected to the second contact terminal of the second relay, and the anode of the second Zener diode is connected to the first terminal of the second photoelectric coupler;

[0030] The cathode of the second freewheeling diode is respectively connected to the first coil end and the power supply end of the second relay, and the anode of the second freewheeling diode is respectively connected to the second coil end of the second relay, the drain of the second NMOS tube, and the power supply end.

[0031] Further, the first voltage dividing module and the second voltage dividing module are both formed by n high-resistance voltage dividing resistors connected in series;

[0032] In the first voltage-dividing module, the first end of the first high-resistance voltage-dividing resistor is respectively connected to the second end of the main positive relay, the second end of the pre-charge relay, and the positive electrode of the output end of the DC high-voltage relay, and the second end of the nth high-resistance voltage-dividing resistor is connected to the anode of the first Schottky diode;

[0033] In the second voltage divider module, the first end of the first high-resistance voltage divider resistor is respectively connected to the first end of the main positive relay, the second end of the pre-charge relay, and the positive electrode of the battery pack, and the second end of the nth high-resistance voltage divider resistor is connected to the anode of the second Schottky diode.

[0034] Furthermore, the first detection circuit also includes a first capacitor, a second capacitor, and a third capacitor;

[0035] The second detection circuit also includes a fourth capacitor, a fifth capacitor, and a sixth capacitor;

[0036] The first end of the first capacitor is connected to the system power supply and the fourth end of the first photoelectric coupler respectively, and the second end of the first capacitor is connected to the third end of the first photoelectric coupler and is grounded;

[0037] The first end of the second capacitor is respectively connected to the second end of the first resistor R1, the gate of the first NMOS transistor, and the first end of the second resistor, and the second end of the second capacitor is respectively connected to the second end of the second resistor and the source of the first NMOS transistor and grounded;

[0038] A first end of the third capacitor is connected to the cathode of the first freewheeling diode and the power supply end respectively, and a second end of the third capacitor is grounded;

[0039] The first end of the fourth capacitor is connected to the system power supply and the fourth end of the second photoelectric coupler respectively, and the second end of the fourth capacitor is connected to the third end of the second photoelectric coupler and is grounded;

[0040] The first end of the fifth capacitor is respectively connected to the second end of the third resistor, the gate of the second NMOS transistor, and the first end of the fourth resistor, and the second end of the fifth capacitor is respectively connected to the second end of the fourth resistor and the source of the second NMOS transistor and is grounded;

[0041] The first end of the sixth capacitor is connected to the cathode of the second freewheeling diode and the power supply end respectively, and the second end of the sixth capacitor is grounded.

[0042] Furthermore, the first detection circuit also includes a fifth resistor and a sixth resistor;

[0043] The second detection circuit also includes a seventh resistor and an eighth resistor;

[0044] A first end of the fifth resistor is connected to the fourth pin of the first photocoupler, and a second end of the fifth resistor is connected to the first end of the first capacitor and the system power supply respectively;

[0045] The first end of the sixth resistor is connected to the third pin of the first photocoupler, and the second end of the sixth resistor is connected to the second end of the first capacitor and grounded;

[0046] The first end of the seventh resistor is connected to the fourth pin of the second photoelectric coupler, and the second end of the seventh resistor is connected to the first end of the fourth capacitor and the system power supply respectively;

[0047] The first end of the eighth resistor is connected to the third pin of the second photoelectric coupler, and the second end of the eighth resistor is connected to the second end of the fourth capacitor and is grounded.

[0048] Further, when the single-chip microcomputer controller controls both the main positive relay and the main negative relay to be disconnected, the first control signal is pulled up to a high level by closing the pre-charge relay and cooperating with the fault diagnosis circuit, and the feedback signal is at a high level, the fault state is that the main positive relay is stuck;

[0049] When the single-chip microcomputer controller controls the main positive relay and the main negative relay to be closed, the pre-charge relay is disconnected, the first control signal is pulled up to a high level, and the feedback signal is a low level, the fault state is that the main positive relay cannot be closed;

[0050] When the single-chip microcomputer controller controls the main positive relay to be disconnected and the main negative relay to be closed, the second control signal is pulled up to a high level, and the feedback signal is a low level, the fault state is that the main negative relay cannot be closed;

[0051] When the single chip microcomputer controller controls the main positive relay and the main negative relay to be disconnected, the pre-charge relay is closed and cooperates with the fault diagnosis circuit to pull the second control signal up to a high level. When the feedback signal is a high level, the fault state is that the main negative relay is stuck.

[0052] The present invention also provides a fault diagnosis method for a DC high voltage relay, using the above-mentioned fault diagnosis circuit for the DC high voltage relay, the method comprises:

[0053] Step 1, the single chip microcomputer controller controls the main positive relay, the main negative relay, and the pre-charge relay to turn on and off;

[0054] Step 2, the single-chip microcomputer controller sends a first control signal and a second control signal to control the first detection circuit and the second detection circuit to detect the main positive relay and the main negative relay, and receives feedback signals sent by the first detection circuit and the second detection circuit after detection;

[0055] Step 3, the single chip microcomputer controller determines the fault status of the main positive relay and the main negative relay according to the feedback signal, and obtains the fault status detection results of the main positive relay and the main negative relay.

[0056] The above scheme of the present invention has the following beneficial effects:

[0057] The fault diagnosis circuit provided by the present invention includes a single-chip microcomputer controller, a first detection circuit and a second detection circuit; the output end of the single-chip microcomputer controller is respectively connected to the control end of the main positive relay, the control end of the main negative relay, the control end of the pre-charge relay, the control end of the first detection circuit, and the control end of the second detection circuit; the first end of the first detection module is respectively connected to the second end of the main positive relay, the second end of the pre-charge relay, and the positive pole of the output end of the DC high-voltage relay; the first end of the second detection module is respectively connected to the first end of the main positive relay, the second end of the pre-charge relay, and the positive pole of the battery pack; the second end of the first detection module is respectively connected to the first end of the main negative relay and the negative pole of the battery pack; the second end of the second detection module is respectively connected to the second end of the main negative relay, the DC high-voltage relay The negative pole of the output terminal is connected; the present invention controls the on and off of the main positive relay, the main negative relay and the pre-charge relay through a single-chip microcomputer controller; and sends a first control signal and a second control signal to control the first detection circuit and the second detection circuit to detect the main positive relay and the main negative relay, and receives the feedback signal sent by the first detection circuit and the second detection circuit after the detection; the single-chip microcomputer controller judges the fault state of the main positive relay and the main negative relay according to the feedback signal, and obtains the fault state detection result of the main positive relay and the main negative relay; compared with the prior art, the present invention can not only judge the adhesion type fault, but also judge the relay cannot close fault according to the different states of the feedback signal, thereby improving the reliability of the relay fault state diagnosis, thereby effectively preventing the occurrence of safety accidents.

[0058] Other beneficial effects of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 is a principle block diagram of an embodiment of the present invention;

[0060] Figure 2 is a circuit schematic diagram of a first detection circuit and a second detection circuit in an embodiment of the present invention;

[0061] Figure 3 The figure is a flow chart of a method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0062] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than 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.

[0063] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0064] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a locking 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 communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0065] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0066] In view of the existing problems, the present invention provides a fault diagnosis circuit and method for a DC high voltage relay.

[0067] like Figure 1 As shown, an embodiment of the present invention provides a fault diagnosis circuit of a DC high-voltage relay, wherein the DC high-voltage relay includes a main positive relay, a main negative relay, a pre-charge relay, and a battery pack, and the fault diagnosis circuit includes:

[0068] A single chip microcomputer controller, a first detection circuit and a second detection circuit;

[0069] The output end of the single-chip microcomputer controller is respectively connected to the control end of the main positive relay, the control end of the main negative relay, the control end of the pre-charge relay, the control end of the first detection circuit, and the control end of the second detection circuit;

[0070] The first end of the first detection module is respectively connected to the second end of the main positive relay, the second end of the pre-charge relay, and the positive electrode PV+ of the output end of the DC high-voltage relay;

[0071] The first end of the second detection module is respectively connected to the first end of the main positive relay, the second end of the pre-charge relay, and the positive electrode HV+ of the battery pack;

[0072] The second end of the first detection module is connected to the first end of the main negative relay and the negative electrode HV- of the battery pack respectively;

[0073] The second end of the second detection module is respectively connected to the second end of the main negative relay and the negative pole PV- of the output end of the DC high voltage relay;

[0074] The third end of the first detection module and the third end of the second detection module are both connected to the input end of the single-chip microcomputer controller;

[0075] The single-chip microcomputer controller controls the main positive relay, main negative relay, and pre-charge relay on and off;

[0076] The single-chip microcomputer controller sends a first control signal and a second control signal to control the first detection circuit and the second detection circuit to detect the main positive relay and the main negative relay, receives feedback signals sent by the first detection circuit and the second detection circuit after detection, and performs fault status judgment based on the feedback signals to obtain the fault status detection results of the main positive relay and the main negative relay.

[0077] In an embodiment of the present invention, the single-chip microcomputer controller controls the main positive relay and the main negative relay to be disconnected, the pre-charge relay to be closed and connected to the second detection circuit, and sends a first control signal to the first detection circuit to detect the main positive relay, sends a second control signal to the second detection circuit to detect the main negative relay, receives feedback signals sent by the first detection circuit and the second detection circuit after detection, and determines whether the main positive relay has a sticking fault and whether the main negative relay has a fault that cannot be closed according to the level state of the feedback signal;

[0078] The single-chip microcomputer controller controls the main positive relay and the main negative relay to close, and sends a first control signal to the first detection circuit to detect the main positive relay, sends a second control signal to the second detection circuit to detect the main negative relay, receives feedback signals sent by the first detection circuit and the second detection circuit after detection, and determines whether the main positive relay has a fault that cannot be closed and whether the main negative relay has a adhesion fault according to the level state of the feedback signal.

[0079] Most preferably, Figure 2 As shown, the first detection circuit includes a first voltage dividing module, a first relay S1, a first photocoupler OC1, a first resistor R1 for driving a first NMOS transistor Q1, the first NMOS transistor Q1, and a second resistor R2;

[0080] The second detection circuit includes a second voltage dividing module, a second relay S2, a second photocoupler OC2, a third resistor R3 for driving the second NMOS transistor Q2, the second NMOS transistor Q2, and a fourth resistor R4;

[0081] The first end of the first voltage-dividing module is respectively connected to the second end of the main positive relay, the second end of the pre-charge relay, and the positive electrode PV+ of the output end of the DC high-voltage relay, the second end of the first voltage-dividing module is connected to the first contact end of the first relay S1, the second contact end of the first relay S1 is connected to the first end of the first photoelectric coupler OC1, the second end of the first photoelectric coupler OC1 is connected to the negative electrode HV- of the battery pack, the second end of the first photoelectric coupler OC1 is connected to the second end of the second photoelectric coupler OC2 through the main negative relay, the third end of the first photoelectric coupler OC1 is respectively connected to the signal transmission end of the single-chip controller and the first end of the first resistor R1, the fourth end of the first photoelectric coupler OC1 is connected to the system power supply, and the system power supply is connected to the second end of the first resistor R1 and grounded;

[0082] A first coil end of the first relay S1 is connected to the power supply end POWER SUPPLY, a second coil end of the first relay S1 is connected to the drain of the first NMOS transistor Q1, a gate of the first NMOS transistor Q1 is connected to the signal transmission end of the single-chip controller through a second resistor R2, and a source of the first NMOS transistor Q1 is grounded;

[0083] The first end of the second voltage-dividing module is respectively connected to the first end of the main positive relay, the second end of the pre-charging relay, and the positive electrode HV+ of the battery pack, the second end of the first voltage-dividing module is connected to the first contact end of the second relay S2, the second contact end of the second relay S2 is connected to the first end of the second photoelectric coupler OC2, the second end of the second photoelectric coupler OC2 is connected to the negative electrode PV- of the output end of the DC high-voltage relay, the third end of the second photoelectric coupler OC2 is respectively connected to the signal transmission end of the single-chip controller and the first end of the third resistor R3, the fourth end of the second photoelectric coupler OC2 is connected to the system power supply, and the system power supply is connected to the second end of the third resistor R3 and grounded;

[0084] The first coil end of the second relay S2 is connected to the power supply end POWER SUPPLY, the second coil end of the second relay S2 is connected to the drain of the second NMOS tube Q2, the gate of the second NMOS tube Q2 is connected to the signal transmission end of the single-chip controller through the fourth resistor R4, and the source of the second NMOS tube Q2 is grounded.

[0085] In the embodiment of the present invention, the first relay S1 and the second relay S2 are both low-power relays, which are used as line switches of the fault diagnosis circuit; the embodiment of the present invention controls the on and off of the main positive relay and the pre-charge relay through the single-chip microcomputer controller, and at the same time cooperates to control the on and off of the low-power relay. The single-chip microcomputer controller reads feedback signals from the first photocoupler OC1 and the second photocoupler OC2 to determine the fault status.

[0086] In the embodiment of the present invention, the power supply terminal POWER SUPPLY is connected to a 24V power supply, which supplies power to the first detection circuit, the second detection circuit, the main positive relay, the main negative relay and the pre-charge relay respectively.

[0087] Most preferably, the first detection circuit further comprises: a first Zener diode ZD1, a first freewheeling diode FD1, and a first Schottky diode SD1 for preventing reverse current;

[0088] The second detection circuit also includes: a second Zener diode ZD2, a second freewheeling diode FD2, and a second Schottky diode SD2 for preventing reverse current;

[0089] An anode of the first Schottky diode SD1 is connected to the second end of the first voltage divider module, and a cathode of the first Schottky diode SD1 is connected to the first contact end of the first relay S1;

[0090] The cathode of the first Zener diode ZD1 is connected to the second contact terminal of the first relay S1, and the anode of the first Zener diode ZD1 is connected to the first terminal of the first photocoupler OC1;

[0091] The cathode of the first freewheeling diode FD1 is respectively connected to the first coil end of the first relay S1 and the power supply end POWERSUPPLY, and the anode of the first freewheeling diode FD1 is respectively connected to the second coil end of the first relay S1, the drain of the first NMOS transistor Q1, and the power supply end POWER SUPPLY;

[0092] An anode of the second Schottky diode SD2 is connected to the second end of the second voltage divider module, and a cathode of the second Schottky diode SD2 is connected to the first contact end of the second relay S2;

[0093] The cathode of the second Zener diode ZD2 is connected to the second contact end of the second relay S2, and the anode of the second Zener diode ZD2 is connected to the first end of the second photocoupler OC2;

[0094] The cathode of the second freewheeling diode FD2 is respectively connected to the first coil end of the second relay S2 and the power supply end POWERSUPPLY, and the anode of the second freewheeling diode FD2 is respectively connected to the second coil end of the second relay S2, the drain of the second NMOS tube Q2, and the power supply end POWER SUPPLY.

[0095] Most preferably, the first voltage dividing module and the second voltage dividing module are both formed by n high-resistance voltage dividing resistors connected in series, namely FR1, FR2, ..., FRn;

[0096] In the first voltage-dividing module, the first end of the first high-resistance voltage-dividing resistor is respectively connected to the second end of the main positive relay, the second end of the pre-charge relay, and the positive electrode PV+ of the output end of the DC high-voltage relay, and the second end of the nth high-resistance voltage-dividing resistor is connected to the anode of the first Schottky diode SD1;

[0097] In the second voltage divider module, the first end of the first high-resistance voltage divider resistor is respectively connected to the first end of the main positive relay, the second end of the pre-charge relay, and the positive pole HV+ of the battery pack, and the second end of the nth high-resistance voltage divider resistor is connected to the anode of the second Schottky diode SD2.

[0098] In the embodiment of the present invention, the selection of the resistors in the first voltage dividing module and the second voltage dividing module needs to take into account the following three formulas:

[0099] V / (n*R)>1mA

[0100] (V / n) 2 / R<0.25W*70%

[0101] V / n<Resistance rated voltage*80%

[0102] In the formula, V represents the total voltage of the battery pack, n represents the number of series resistors, R represents the resistance of a single resistor, 1mA is the forward current of the optocoupler, which is used to ensure the saturation conduction of the optocoupler, 0.25W refers to the rated power of the series resistor, and a 30% margin is left.

[0103] Most preferably, the first detection circuit further includes a first capacitor C1, a second capacitor C2, and a third capacitor C3 for filtering;

[0104] The second detection circuit also includes a fourth capacitor C4, a fifth capacitor C5, and a sixth capacitor C6 for filtering;

[0105] A first end of the first capacitor C1 is connected to the system power supply and the fourth end of the first photocoupler OC1 respectively, and a second end of the first capacitor C1 is connected to the third end of the first photocoupler OC1 and is grounded;

[0106] The first end of the second capacitor C2 is respectively connected to the second end of the first resistor R1, the gate of the first NMOS transistor Q1, and the first end of the second resistor R2, and the second end of the second capacitor C2 is respectively connected to the second end of the second resistor R2 and the source of the first NMOS transistor Q1 and grounded;

[0107] A first end of the third capacitor C3 is connected to the cathode of the first freewheeling diode FD1 and the power supply terminal POWER SUPPLY respectively, and a second end of the third capacitor C3 is grounded;

[0108] A first end of the fourth capacitor C4 is connected to the system power supply and the fourth end of the second photocoupler OC2 respectively, and a second end of the fourth capacitor C4 is connected to the third end of the second photocoupler OC2 and is grounded;

[0109] The first end of the fifth capacitor C5 is respectively connected to the second end of the third resistor R3, the gate of the second NMOS transistor Q2, and the first end of the fourth resistor R4, and the second end of the fifth capacitor C5 is respectively connected to the second end of the fourth resistor R4 and the source of the second NMOS transistor Q2 and grounded;

[0110] A first end of the sixth capacitor C6 is connected to the cathode of the second freewheeling diode FD2 and the power supply terminal POWER SUPPLY respectively, and a second end of the sixth capacitor C6 is grounded.

[0111] Most preferably, the first detection circuit further includes a fifth resistor R5 and a sixth resistor R6 for current limiting;

[0112] The second detection circuit also includes a seventh resistor R7 and an eighth resistor R8 for current limiting;

[0113] A first end of the fifth resistor R5 is connected to the fourth pin of the first photocoupler OC1, and a second end of the fifth resistor R5 is connected to the first end of the first capacitor C1 and the system power supply respectively;

[0114] The first end of the sixth resistor R6 is respectively connected to the third pin of the first photocoupler OC1, and the second end of the sixth resistor R6 is connected to the second end of the first capacitor C1 and grounded;

[0115] A first end of the seventh resistor R7 is connected to the fourth pin of the second photocoupler OC2, and a second end of the seventh resistor R7 is connected to the first end of the fourth capacitor C4 and the system power supply respectively;

[0116] The first end of the eighth resistor R8 is connected to the third pin of the second photocoupler OC2 , and the second end of the eighth resistor R8 is connected to the second end of the fourth capacitor C4 and grounded.

[0117] like Figure 3 As shown, an embodiment of the present invention further provides a fault diagnosis method for a DC high voltage relay, and the fault diagnosis method for a DC high voltage relay as described above is applied, and the method includes:

[0118] Step 1, the single chip microcomputer controller controls the main positive relay, the main negative relay, and the pre-charge relay to turn on and off;

[0119] Step 2, the single-chip microcomputer controller sends a first control signal and a second control signal to control the first detection circuit and the second detection circuit to detect the main positive relay and the main negative relay and obtain a feedback signal;

[0120] Step 3: The first detection module and the second detection module send the feedback signal to the single-chip microcomputer controller for fault status judgment to obtain the fault status detection results of the main positive relay and the main negative relay.

[0121] Specifically, when the single-chip controller controls the main positive relay and the main negative relay to be disconnected, the pre-charge relay is closed and cooperates with the fault diagnosis circuit to ensure that the optocoupler is electrically connected to the output bus, and the first control signal input to the first detection circuit is pulled up to a high level. When the feedback signal is a high level, the fault state is that the main positive relay is stuck. When the feedback signal is a low level, the main positive relay is normal;

[0122] When the single-chip microcomputer controller controls the main positive relay and the main negative relay to be closed and the pre-charge relay to be disconnected, the first control signal input to the first detection circuit is pulled up to a high level, and the feedback signal is a low level, the fault state is that the main positive relay cannot be closed, and when the feedback signal is a high level, the main positive relay is normal;

[0123] When the single-chip microcomputer controller controls the main positive relay to be disconnected and the main negative relay to be closed, the second control signal input to the second detection circuit is pulled up to a high level, and the feedback signal is at a low level, the fault state is that the main negative relay cannot be closed, and when the feedback signal is at a high level, the main negative relay is normal;

[0124] When the single-chip controller controls the main positive relay and the main negative relay to be disconnected, the pre-charge relay is closed to cooperate with the fault diagnosis circuit to pull up the second control signal input to the second detection circuit to a high level. When the feedback signal is a high level, the fault state is that the main negative relay is stuck. When the feedback signal is a low level, the main negative relay is normal, as shown in Table 1 below:

[0125] Table 1

[0126]

[0127]

[0128] When the main negative relay is closed, and then the pre-charge relay is closed, the main positive relay is closed and the pre-charge relay is disconnected when the pressure difference is less than a certain value, that is, when the output voltage is greater than 90% of the battery voltage.

[0129] The fault diagnosis circuit provided by the embodiment of the present invention only generates power consumption during the detection process, and the power consumption sizes are: total voltage platform V / (n*R), relay power consumption is about 300mW, and minimum system platform v / (1k+3k) is about 3mW; it can be seen that the power consumption is extremely low.

[0130] The fault diagnosis circuit provided by the embodiment of the present invention includes a single-chip microcomputer controller, a first detection circuit and a second detection circuit; the output end of the single-chip microcomputer controller is respectively connected to the control end of the main positive relay, the control end of the main negative relay, the control end of the pre-charge relay, the control end of the first detection circuit, and the control end of the second detection circuit; the first end of the first detection module is respectively connected to the second end of the main positive relay, the second end of the pre-charge relay, and the positive pole of the DC high-voltage relay output end; the first end of the second detection module is respectively connected to the first end of the main positive relay, the second end of the pre-charge relay, and the positive pole of the battery pack; the second end of the first detection module is respectively connected to the first end of the main negative relay and the negative pole of the battery pack; the second detection module The second end of is respectively connected to the second end of the main negative relay and the negative pole of the DC high-voltage relay output end; the present invention controls the on and off of the main positive relay, the main negative relay and the pre-charge relay through a single-chip microcomputer controller; and sends a first control signal and a second control signal to control the first detection circuit and the second detection circuit to detect the main positive relay and the main negative relay and obtain a feedback signal, and sends the feedback signal to the single-chip microcomputer controller for fault state judgment, and obtains the fault state detection result of the main positive relay and the main negative relay; compared with the prior art, it can not only judge the adhesion type fault, but also judge the relay cannot close fault, thereby improving the reliability of the relay fault state diagnosis, thereby effectively preventing the occurrence of safety accidents.

[0131] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A fault diagnosis circuit for a DC high-voltage relay, the DC high-voltage relay comprising a main positive relay, a main negative relay, a pre-charge relay, and a battery pack, characterized in that: The fault diagnosis circuit comprises: A single chip microcomputer controller, a first detection circuit and a second detection circuit; The output end of the single-chip controller is respectively connected to the control end of the main positive relay, the control end of the main negative relay, the control end of the pre-charge relay, the control end of the first detection circuit, and the control end of the second detection circuit; The first end of the first detection module is respectively connected to the second end of the main positive relay, the second end of the pre-charge relay, and the positive electrode of the output end of the DC high-voltage relay; The first end of the second detection module is respectively connected to the first end of the main positive relay, the second end of the pre-charge relay, and the positive electrode of the battery pack; The second end of the first detection module is connected to the first end of the main negative relay and the negative electrode of the battery pack respectively; The second end of the second detection module is respectively connected to the second end of the main negative relay and the negative pole of the output end of the DC high-voltage relay; The third end of the first detection module and the third end of the second detection module are both connected to the input end of the single-chip controller; The single chip controller controls the main positive relay, the main negative relay and the pre-charge relay to be turned on and off; The single-chip microcomputer controller sends a first control signal and a second control signal to control the first detection circuit and the second detection circuit to detect the main positive relay and the main negative relay, receives feedback signals sent by the first detection circuit and the second detection circuit after detection, and performs fault status judgment based on the feedback signals to obtain fault status detection results of the main positive relay and the main negative relay.

2. The fault diagnosis circuit of the DC high voltage relay according to claim 1, characterized in that: The first detection circuit includes a first voltage dividing module, a first relay, a first photocoupler, a first resistor R1, a first NMOS tube, and a second resistor; The second detection circuit includes a second voltage divider module, a second relay, a second photocoupler, a third resistor, a second NMOS tube, and a fourth resistor; The first end of the first voltage divider module is respectively connected to the second end of the main positive relay, the second end of the pre-charge relay, and the positive electrode of the DC high-voltage relay output end, the second end of the first voltage divider module is connected to the first contact end of the first relay, the second contact end of the first relay is connected to the first end of the first photoelectric coupler, the second end of the first photoelectric coupler is connected to the negative electrode of the battery pack, the second end of the first photoelectric coupler is connected to the second end of the second photoelectric coupler through the main negative relay, the third end of the first photoelectric coupler is respectively connected to the signal transmission end of the single-chip controller and the first end of the first resistor R1, the fourth end of the first photoelectric coupler is connected to the system power supply, and the system power supply is connected to the second end of the first resistor R1 and grounded; The first coil end of the first relay is connected to the power supply end, the second coil end of the first relay is connected to the drain of the first NMOS tube, the gate of the first NMOS tube is connected to the signal transmission end of the single-chip controller through the second resistor, and the source of the first NMOS tube is grounded; The first end of the second voltage divider module is respectively connected to the first end of the main positive relay, the second end of the pre-charge relay, and the positive electrode of the battery pack, the second end of the first voltage divider module is connected to the first contact end of the second relay, the second contact end of the second relay is connected to the first end of the second photoelectric coupler, the second end of the second photoelectric coupler is connected to the negative electrode of the output end of the DC high-voltage relay, the third end of the second photoelectric coupler is respectively connected to the signal transmission end of the single-chip controller and the first end of the third resistor, the fourth end of the second photoelectric coupler is connected to the system power supply, and the system power supply is connected to the second end of the third resistor and grounded; The first coil end of the second relay is connected to the power supply end, the second coil end of the second relay is connected to the drain of the second NMOS tube, the gate of the second NMOS tube is connected to the signal transmission end of the single-chip controller through the fourth resistor, and the source of the second NMOS tube is grounded.

3. The fault diagnosis circuit of the DC high voltage relay according to claim 2, characterized in that: The first detection circuit further includes: a first Schottky diode, a first Zener diode, and a first freewheeling diode; The second detection circuit further includes: a second Schottky diode, a second Zener diode, and a second freewheeling diode; The anode of the first Schottky diode is connected to the second end of the first voltage divider module, and the cathode of the first Schottky diode is connected to the first contact end of the first relay; The cathode of the first Zener diode is connected to the second contact end of the first relay, and the anode of the first Zener diode is connected to the first end of the first photocoupler; The cathode of the first freewheeling diode is respectively connected to the first coil end of the first relay and the power supply end, and the anode of the first freewheeling diode is respectively connected to the second coil end of the first relay, the drain of the first NMOS tube, and the power supply end; An anode of the second Schottky diode is connected to the second end of the second voltage divider module, and a cathode of the second Schottky diode is connected to the first contact end of the second relay; The cathode of the second Zener diode is connected to the second contact terminal of the second relay, and the anode of the second Zener diode is connected to the first terminal of the second photocoupler; The cathode of the second freewheeling diode is respectively connected to the first coil end of the second relay and the power supply end, and the anode of the second freewheeling diode is respectively connected to the second coil end of the second relay, the drain of the second NMOS tube, and the power supply end.

4. The fault diagnosis circuit of the DC high voltage relay according to claim 3, characterized in that: The first voltage dividing module and the second voltage dividing module are both formed by connecting n high-resistance voltage dividing resistors in series; In the first voltage-dividing module, the first end of the first high-resistance voltage-dividing resistor is respectively connected to the second end of the main positive relay, the second end of the pre-charge relay, and the positive electrode of the output end of the DC high-voltage relay, and the second end of the nth high-resistance voltage-dividing resistor is connected to the anode of the first Schottky diode; In the second voltage divider module, the first end of the first high-resistance voltage divider resistor is respectively connected to the first end of the main positive relay, the second end of the pre-charge relay, and the positive electrode of the battery pack, and the second end of the nth high-resistance voltage divider resistor is connected to the anode of the second Schottky diode.

5. The fault diagnosis circuit of the DC high voltage relay according to claim 4, characterized in that: The first detection circuit also includes a first capacitor, a second capacitor, and a third capacitor; The second detection circuit also includes a fourth capacitor, a fifth capacitor, and a sixth capacitor; The first end of the first capacitor is connected to the system power supply and the fourth end of the first photoelectric coupler respectively, and the second end of the first capacitor is connected to the third end of the first photoelectric coupler and is grounded; The first end of the second capacitor is respectively connected to the second end of the first resistor R1, the gate of the first NMOS transistor, and the first end of the second resistor, and the second end of the second capacitor is respectively connected to the second end of the second resistor and the source of the first NMOS transistor and grounded; The first end of the third capacitor is connected to the cathode of the first freewheeling diode and the power supply end respectively, and the second end of the third capacitor is grounded; The first end of the fourth capacitor is connected to the system power supply and the fourth end of the second photoelectric coupler respectively, and the second end of the fourth capacitor is connected to the third end of the second photoelectric coupler and is grounded; The first end of the fifth capacitor is respectively connected to the second end of the third resistor, the gate of the second NMOS transistor, and the first end of the fourth resistor, and the second end of the fifth capacitor is respectively connected to the second end of the fourth resistor and the source of the second NMOS transistor and is grounded; A first end of the sixth capacitor is connected to the cathode of the second freewheeling diode and the power supply end respectively, and a second end of the sixth capacitor is grounded.

6. The fault diagnosis circuit of the DC high voltage relay according to claim 5, characterized in that: The first detection circuit also includes a fifth resistor and a sixth resistor; The second detection circuit also includes a seventh resistor and an eighth resistor; The first end of the fifth resistor is connected to the fourth pin of the first photoelectric coupler, and the second end of the fifth resistor is connected to the first end of the first capacitor and the system power supply respectively; The first end of the sixth resistor is respectively connected to the third pin of the first photoelectric coupler, and the second end of the sixth resistor is connected to the second end of the first capacitor and grounded; The first end of the seventh resistor is connected to the fourth pin of the second photoelectric coupler, and the second end of the seventh resistor is connected to the first end of the fourth capacitor and the system power supply respectively; The first end of the eighth resistor is connected to the third pin of the second photoelectric coupler, and the second end of the eighth resistor is connected to the second end of the fourth capacitor and is grounded.

7. The fault diagnosis circuit of the DC high voltage relay according to claim 6, characterized in that: When the single-chip controller controls the main positive relay and the main negative relay to be disconnected, the pre-charge relay is closed to cooperate with the fault diagnosis circuit to pull the first control signal up to a high level, and the feedback signal is at a high level, the fault state is that the main positive relay is stuck; When the single-chip controller controls the main positive relay and the main negative relay to be closed, the pre-charge relay to be disconnected, the first control signal is pulled up to a high level, and the feedback signal is a low level, the fault state is that the main positive relay cannot be closed; When the single chip controller controls the main positive relay to be disconnected and the main negative relay to be closed, the second control signal is pulled up to a high level, and the feedback signal is a low level, the fault state is that the main negative relay cannot be closed; When the single-chip microcomputer controller controls the main positive relay and the main negative relay to be disconnected, and the pre-charging relay is closed to cooperate with the fault diagnosis circuit to pull the second control signal up to a high level, and the feedback signal is at a high level, the fault state is that the main negative relay is stuck.

8. A fault diagnosis method for a DC high voltage relay, characterized in that: Using the fault diagnosis circuit of the DC high voltage relay according to any one of claims 1 to 7, the method comprises: Step 1, the single chip microcomputer controller controls the main positive relay, the main negative relay, and the pre-charge relay to turn on and off; Step 2, the single-chip microcomputer controller sends a first control signal and a second control signal to control the first detection circuit and the second detection circuit to detect the main positive relay and the main negative relay and receive feedback signals sent by the first detection circuit and the second detection circuit after detection; Step 3, the single chip microcomputer controls the fault status of the main positive relay and the main negative relay according to the feedback signal to obtain the fault status detection results of the main positive relay and the main negative relay.

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