Relay state detection device and method

Abstract

The invention discloses a relay state detection device and method. The device comprises a constant current source circuit, a current sensor and a main controller. Wherein the main controller controls the constant current source circuit to respectively apply constant current to a positive relay connected in series with the positive end of a bus and a negative relay connected in series with the negative end of the bus; the current sensor is in signal connection with the main controller and is used for acquiring a positive end current of the positive end of the bus and a negative end current of the negative end of the bus and sending the positive end current and the negative end current to the main controller; the main controller receives the positive end current and the negative end current and compares the positive end current and the negative end current with the constant current so as to determine the state of the positive pole relay and the state of the negative pole relay according to the comparison result, and the accuracy and efficiency of relay state detection are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicles, and in particular to a state diagnosis device and method for a relay. Background Art

[0002] In electric vehicles and large-scale energy storage battery systems, voltages often reach hundreds of volts. Therefore, ensuring high-voltage power supply safety has become a key research and development area in high-voltage battery systems. To address this, technicians use high-voltage relays throughout the battery's operating circuit to maintain normal operation.

[0003] Under normal conditions, each high-voltage relay in the circuit maintains circuit safety by opening or closing normally. However, if a relay fails, the circuit will have a high-voltage risk.

[0004] To address this issue, existing researchers have developed various techniques for relay fault diagnosis, repair, and circuit safety. Existing relay diagnostic methods often compare the voltages at the front and rear ends of the relay to determine the fault. However, this method cannot accurately determine the relay's status based on the voltages at both ends when the external voltage is close to or equal to the battery voltage. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention discloses a relay state detection device and method to solve the above defects in the prior art and improve the accuracy of relay state detection.

[0006] In order to achieve the above object, the present invention discloses a state detection device for a relay, comprising a constant current source circuit, a current sensor and a main controller;

[0007] The constant current source circuit is connected to the main controller signal so that the main controller controls the constant current source circuit to apply a constant current to the positive relay connected in series to the positive end of the bus and the negative relay connected in series to the negative end of the bus; wherein the input end of the positive relay and the input end of the negative relay are respectively connected to the output end of the constant current source circuit; the output end of the positive relay and the output end of the negative relay are respectively connected to the input end of the constant current source circuit;

[0008] The current sensor is connected to the main controller signal, and is used to obtain the positive end current of the positive end of the busbar and the negative end current of the negative end of the busbar, and send the positive end current and the negative end current to the main controller; wherein the output end of the positive pole relay and the output end of the negative pole relay are respectively connected to the input end of the current sensor; the input end of the constant current source circuit is connected to the output end of the current sensor;

[0009] The main controller receives the positive terminal current and the negative terminal current, and compares the positive terminal current and the negative terminal current with the constant current respectively, so as to determine the status of the positive electrode relay and the negative electrode relay according to the comparison results.

[0010] The present invention discloses a relay status detection device, which is provided with a constant current source circuit to apply an undisturbed constant current to a positive relay connected in series to the positive end of a busbar and a negative relay connected in series to the negative end of the busbar, respectively, so as to avoid interference from external voltage through the constant current source circuit, and then obtain the positive end current flowing through the positive relay and the negative end current flowing through the negative relay after the constant current is applied. Then, the positive end current, the negative end current and the constant current are compared to accurately detect the status of the positive relay and the negative relay.

[0011] As a preferred example, the constant current source circuit includes a constant current source, a first switch, a second switch, a first diode and a second diode;

[0012] The input end of the first switch and the input end of the second switch are electrically connected to the output end of the constant current source respectively; the output end of the positive relay and the output end of the negative relay are electrically connected to the input end of the constant current source;

[0013] The output end of the first switch is electrically connected to the input end of the first diode; the output end of the second switch is electrically connected to the input end of the second diode;

[0014] The output end of the first diode is electrically connected to the input end of the positive relay;

[0015] The output end of the second diode is electrically connected to the input end of the negative relay.

[0016] The present invention provides a constant current source to provide a stable constant current, avoiding the influence of external voltages and improving detection accuracy. The first and second switches are provided to control the order in which current is applied to the positive and negative relays, allowing accurate determination of the relay states based on the application sequence. The diode is provided to protect the constant current source, preventing damage from terminal voltage backflow.

[0017] As a preferred example, the main controller controls the first switch to be closed and controls the second switch to be open, so as to apply the constant current to the positive relay through the constant current source;

[0018] The main controller receives the positive end current of the busbar positive end sent by the current sensor, and obtains the positive end difference between the positive end current and the constant current;

[0019] When the main controller determines that the positive end difference is within a preset tolerance range, the main controller controls the first switch to be opened and controls the second switch to be closed, so as to apply the constant current to the negative relay through the constant current source.

[0020] According to the circuit loop formed by the constant current source circuit, the positive relay, and the negative relay, the present invention first closes the first switch to apply a constant current to the positive relay, thereby performing a preliminary current loop status detection. During the status detection process, if the difference between the current of the positive relay and the constant current is determined to be within a tolerance range, indicating that the current flowing through the positive relay is relatively large, it can be preliminarily determined that the positive relay is stuck. To detect the negative relay, the second switch can be closed, the first switch opened, and a constant current applied to the negative relay for status detection.

[0021] As a preferred example, the main controller is further configured to receive the negative end current of the negative end of the busbar sent by the current sensor, and obtain a negative end difference between the negative end current and the constant current;

[0022] When the main controller determines that the negative terminal difference is not within the tolerance range, the main controller determines that the state of the positive relay is stuck and the state of the negative relay is disconnected.

[0023] The present invention uses a constant current unaffected by external voltage as a reference, and measures the difference between the negative terminal current flowing through the negative relay and the constant current to determine the magnitude of the current flowing through the negative terminal of the negative relay, enabling accurate identification of the negative relay's state. If the negative terminal difference is outside the tolerance range, it indicates that the negative terminal current flowing through the negative relay is relatively low, indicating that the negative relay is disconnected.

[0024] As a preferred example, when the main controller determines that the negative terminal difference is within the tolerance range, the main controller determines that the status of the positive relay and the negative relay is adhesion.

[0025] When the present invention determines that the negative terminal difference is not within the tolerance range, it means that the negative terminal current flowing through the negative electrode relay is relatively small at this time, and it can be determined that the negative electrode relay is in a sticking state.

[0026] As a preferred example, when the main controller determines that the positive end difference is not within a preset tolerance range, it receives the negative end current of the negative end of the bus sent by the current sensor, and obtains the negative end difference between the negative end current and the constant current;

[0027] The main controller determines that the state of the positive relay is disconnected and the state of the negative relay is stuck after determining that the negative terminal difference is within the tolerance range.

[0028] In the present invention, when the first switch is closed to apply a constant current to the positive relay to perform a preliminary current loop status detection, if the difference between the current of the positive relay and the constant current is determined to be outside the tolerance range, it indicates that the current flowing through the positive relay is relatively small, and a preliminary judgment can be made that the positive relay is disconnected. To detect the negative relay, only the negative terminal current of the negative relay needs to be obtained for status detection. If the negative terminal difference is within the tolerance range, it indicates that the negative terminal current flowing through the negative relay is relatively large, and the negative relay can be determined to be in a stuck state.

[0029] As a preferred example, the main controller determines that the status of the positive relay and the negative relay is disconnected when determining that the negative end difference is not within the tolerance range.

[0030] When the present invention determines that the negative terminal difference is not within the tolerance range, it means that the negative terminal current flowing through the negative electrode relay is relatively small at this time, and it can be determined that the negative electrode relay is in the disconnected state.

[0031] On the other hand, the present invention also discloses a method for detecting the state of a relay, comprising:

[0032] Applying a constant current to the positive relay connected in series to the positive end of the busbar and the negative relay connected in series to the negative end of the busbar respectively;

[0033] Obtaining a positive terminal current flowing through the positive relay at the positive terminal of the busbar and a negative terminal current flowing through the negative relay at the negative terminal of the busbar;

[0034] Comparison results of the positive terminal current, the negative terminal current, and the constant current are respectively obtained to determine the states of the positive electrode relay and the negative electrode relay according to the comparison results.

[0035] The present invention discloses a method for detecting the state of a relay, which is configured to apply a constant current to a positive relay connected in series to the positive end of a busbar and a negative relay connected in series to the negative end of the busbar, respectively, to avoid interference from an external voltage. The method then obtains the positive end current flowing through the positive relay and the negative end current flowing through the negative relay after the constant current is applied. The positive end current, the negative end current, and the constant current are then compared to accurately detect the states of the positive relay and the negative relay.

[0036] As a preferred example, the step of applying a constant current to the positive relay connected in series to the positive end of the bus and the negative relay connected in series to the negative end of the bus respectively includes:

[0037] First, applying the constant current to the positive relay to obtain the positive terminal current flowing through the positive relay at the positive terminal of the busbar;

[0038] Obtaining a positive end difference between the positive end current and the constant current;

[0039] When the positive terminal difference is within a preset tolerance range, the constant current is applied to the negative electrode relay.

[0040] The present invention first applies a constant current to the positive relay based on the circuit loop to perform a preliminary current loop status detection. During the status detection process, if the difference between the current of the positive relay and the constant current is determined to be within the tolerance range, it indicates that the current flowing through the positive relay is relatively large, and it can be preliminarily determined that the positive relay is stuck. At this time, in order to detect the negative relay, a constant current can be applied to the negative relay for status detection.

[0041] As a preferred example, respectively obtaining comparison results of the positive terminal current, the negative terminal current, and the constant current, and determining the states of the positive electrode relay and the negative electrode relay according to the comparison results, includes:

[0042] Obtaining a negative terminal current flowing through the negative electrode relay at the negative terminal of the busbar, and obtaining a negative terminal difference between the negative terminal current and the constant current;

[0043] When the negative terminal difference is not within the tolerance range, it is determined that the state of the positive relay is stuck and the state of the negative relay is disconnected.

[0044] The present invention uses a constant current unaffected by external voltage as a reference, and measures the difference between the negative terminal current flowing through the negative relay and the constant current to determine the magnitude of the current flowing through the negative terminal of the negative relay, enabling accurate identification of the negative relay's state. If the negative terminal difference is outside the tolerance range, it indicates that the negative terminal current flowing through the negative relay is relatively low, indicating that the negative relay is disconnected.

[0045] As a preferred example, respectively obtaining comparison results of the positive terminal current, the negative terminal current, and the constant current, and determining the states of the positive electrode relay and the negative electrode relay according to the comparison results, includes:

[0046] When the negative terminal difference is within the tolerance range, it is determined that the states of the positive relay and the negative relay are stuck.

[0047] When the present invention determines that the negative terminal difference is not within the tolerance range, it means that the negative terminal current flowing through the negative electrode relay is relatively small at this time, and it can be determined that the negative electrode relay is in a sticking state.

[0048] As a preferred example, respectively obtaining comparison results of the positive terminal current, the negative terminal current, and the constant current, and determining the states of the positive electrode relay and the negative electrode relay according to the comparison results, includes:

[0049] When the positive end difference is not within a preset tolerance range, obtaining a negative end current flowing through the negative electrode relay in the negative end of the busbar, and obtaining a negative end difference between the negative end current and the constant current;

[0050] When the negative terminal difference is within the tolerance range, it is determined that the state of the positive relay is disconnected and the state of the negative relay is stuck.

[0051] In the present invention, when applying a constant current to the positive relay to perform a preliminary current loop status detection, if the difference between the current of the positive relay and the constant current is not within the tolerance range, it indicates that the current flowing through the positive relay is relatively small, and the positive relay can be preliminarily determined to be disconnected. At this time, in order to detect the negative relay, it is only necessary to obtain the negative terminal current of the negative relay to perform status detection. If the negative terminal difference is within the tolerance range, it indicates that the negative terminal current flowing through the negative relay is relatively large, and the negative relay can be determined to be in a stuck state.

[0052] As a preferred example, respectively obtaining comparison results of the positive terminal current, the negative terminal current, and the constant current, and determining the states of the positive electrode relay and the negative electrode relay according to the comparison results, includes:

[0053] When the negative terminal difference is not within the tolerance range, it is determined that the states of the positive relay and the negative relay are disconnected.

[0054] When the present invention determines that the negative terminal difference is not within the tolerance range, it means that the negative terminal current flowing through the negative electrode relay is relatively small at this time, and it can be determined that the negative electrode relay is in the disconnected state. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 : A schematic structural diagram of a relay status detection device disclosed in an embodiment of the present invention;

[0056] Figure 2 : A schematic flow chart of a relay status detection method disclosed in an embodiment of the present invention;

[0057] Figure 3 : is a structural diagram of a state detection circuit of a relay disclosed in another embodiment of the present invention;

[0058] Figure 4 : A schematic diagram of a state detection process of a relay disclosed in another embodiment of the present invention;

[0059] Figure 5 : is a schematic diagram of a current path corresponding to when the first switch is closed, as disclosed in another embodiment of the present invention;

[0060] Figure 6 : is a schematic diagram of another current path corresponding to when the first switch is closed, disclosed in another embodiment of the present invention;

[0061] Figure 7 : is a schematic diagram of another current path corresponding to when the first switch is closed, disclosed in another embodiment of the present invention;

[0062] Figure 8 : A schematic diagram of the current path of the equivalent circuit corresponding to when the first switch is closed according to another embodiment of the present invention. DETAILED DESCRIPTION

[0063] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0064] Example 1

[0065] This embodiment discloses a state detection device for a relay. Specifically, the structure of the state detection device can be referred to Figure 1 , mainly includes a constant current source circuit 101, a current sensor 102 and a main controller 103.

[0066] like Figure 1 As shown, the constant current source circuit 101 is connected to the main controller 103 by signal, so that the main controller 103 controls the constant current source circuit 101 to apply constant current to the positive relay connected in series to the positive end of the bus and the negative relay connected in series to the negative end of the bus.

[0067] The current sensor 102 is connected to the main controller 103 signal, and is used to obtain the positive end current of the positive end of the bus and the negative end current of the negative end of the bus, and send the positive end current and the negative end current to the main controller 103; the input end of the constant current source circuit 101 is connected to the output end of the current sensor 102.

[0068] The main controller 103 receives the positive terminal current and the negative terminal current, and compares the positive terminal current and the negative terminal current with the constant current respectively, so as to determine the status of the positive electrode relay and the negative electrode relay according to the comparison results.

[0069] Specifically, in order to Figure 1 The status detection device shown obtains the status detection result of the relay, and sets the output end of the constant current source circuit 101 to be connected to the input end of the positive relay connected in series with the positive end of the bus and the input end of the negative relay connected in series with the negative end of the bus; and the input end of the constant current source circuit 101 is connected to the output end of the positive relay connected in series with the positive end of the bus and the output end of the negative relay connected in series with the negative end of the bus.

[0070] Furthermore, in order to obtain the current at both ends of the positive relay and the negative relay through the current sensor 102, the input end of the current sensor 102 is connected to the output end of the positive relay and the output end of the negative relay respectively.

[0071] In certain implementations of this embodiment, in order to improve the resistance of the constant current source circuit 101 to external voltage and thereby provide a stable constant current for the positive relay and the negative relay, the constant current source circuit is configured to include a constant current source to provide a constant current through the constant current source.

[0072] Furthermore, in order to more accurately obtain the states corresponding to the positive relay and the negative relay respectively, a first switch and a second switch can be set in the constant current source circuit to control the current application sequence of the constant current source to the positive relay and the negative relay through the first switch and the second switch.

[0073] Preferably, in the process of the constant current source providing current to the relay, in order to protect the constant current source, a first diode and a second diode can be set in the constant current source circuit to protect the constant current source and prevent the terminal voltage from flowing back and damaging the constant current source.

[0074] Specifically, referring to the functional settings of the above-mentioned constant current source, the first switch, the second switch, the first diode and the second diode, the connection relationship between the constant current source, the first switch, the second switch, the first diode and the second diode is: the input end of the first switch and the input end of the second switch are electrically connected to the output end of the constant current source respectively; the output end of the positive relay and the output end of the negative relay are electrically connected to the input end of the constant current source; the output end of the first switch is electrically connected to the input end of the first diode; the output end of the second switch is electrically connected to the input end of the second diode; the output end of the first diode is electrically connected to the input end of the positive relay; and the output end of the second diode is electrically connected to the input end of the negative relay.

[0075] In certain implementations of this embodiment, referring to the structure of the constant current source circuit 101, based on the main controller 103 controlling the order in which the constant current source circuit 101 applies current to the positive relay and the negative relay to obtain a state detection result of the relay, the process of the main controller 103 detecting the relay includes the following steps:

[0076] S1: The main controller 103 controls the first switch to be closed and the second switch to be opened, so as to apply the constant current to the positive relay through the constant current source;

[0077] S2: The main controller 103 receives the positive end current of the busbar positive end sent by the current sensor 102, and obtains the positive end difference between the positive end current and the constant current;

[0078] S3: When the main controller 103 determines that the positive end difference is within a preset tolerance range, the main controller 103 controls the first switch to be opened and controls the second switch to be closed, so as to apply the constant current to the negative relay through the constant current source.

[0079] In steps S1 to S3, based on the positive relay being connected to the positive end of the busbar and the negative relay being connected to the negative end of the busbar, the main controller 103 first closes the first switch to apply a constant current to the positive relay in order to establish a current loop for detection. This allows for a preliminary current loop status check. During this status check, if the difference between the current flowing through the positive relay and the constant current is found to be within a tolerance range, indicating that the current flowing through the positive relay is relatively high, a preliminary determination can be made that the positive relay is stuck. To detect the negative relay, the second switch can be closed, the first switch opened, and a constant current applied to the negative relay for status detection.

[0080] Furthermore, based on the execution condition of step S3 that the positive end difference is within a preset tolerance range, when the positive end difference is not within the preset tolerance range, the main controller 103 executes the following steps:

[0081] S4: When the main controller 103 determines that the positive end difference is not within a preset tolerance range, it receives the negative end current of the negative end of the busbar sent by the current sensor 102 and obtains the negative end difference between the negative end current and the constant current;

[0082] S5: After determining that the negative terminal difference is within the tolerance range, the main controller 103 determines that the state of the positive relay is disconnected and the state of the negative relay is adhered.

[0083] In steps S4 and S5, when the first switch is closed to apply a constant current to the positive relay to perform a preliminary current loop status detection, if the difference between the current of the positive relay and the constant current is not within the tolerance range, it indicates that the current flowing through the positive relay is relatively small, and the positive relay can be preliminarily determined to be disconnected. To detect the negative relay, only the negative terminal current of the negative relay needs to be obtained for status detection. If the negative terminal difference is within the tolerance range, it indicates that the negative terminal current of the negative relay is relatively large, and the negative relay can be determined to be in a stuck state.

[0084] Furthermore, based on the execution condition of step S5 that the positive end difference is not within the preset tolerance range and the negative end difference is within the tolerance range, when the positive end difference is not within the preset tolerance range and the negative end difference is not within the tolerance range, the main controller 103 executes the following steps:

[0085] S6: When determining that the negative terminal difference is not within the tolerance range, the main controller 103 determines that the status of the positive relay and the negative relay is disconnected.

[0086] In step S6, when it is determined that the negative terminal difference is not within the tolerance range, it means that the negative terminal current flowing through the negative electrode relay is relatively small at this time, and it can be determined that the negative electrode relay is in the disconnected state.

[0087] Furthermore, after step S3 is executed, that is, after the constant current source applies the constant current to the negative relay, the main controller 103 executes the following steps:

[0088] S7: The main controller 103 receives the negative end current of the negative end of the busbar sent by the current sensor 102, and obtains the negative end difference between the negative end current and the constant current;

[0089] S8: When the main controller 103 determines that the negative terminal difference is not within the tolerance range, it determines that the state of the positive relay is adhered and the state of the negative relay is disconnected.

[0090] In steps S7 and S8, a constant current unaffected by external voltage is used as a reference. The difference between the negative terminal current flowing through the negative relay and the constant current is obtained to determine the current magnitude of the negative terminal current flowing through the negative relay, thereby accurately identifying the state of the negative relay. If the negative terminal difference is not within the tolerance range, it indicates that the negative terminal current flowing through the negative relay is relatively low, and the negative relay can be determined to be in the disconnected state.

[0091] Furthermore, based on the execution condition of step S8 that the negative end difference is not within the preset tolerance range, when the negative end difference is within the preset tolerance range, the main controller 103 executes the following steps:

[0092] S9: When the main controller 103 determines that the negative terminal difference is within the tolerance range, it determines that the status of the positive relay and the negative relay is adhesion.

[0093] In step S9 , when it is determined that the negative terminal difference is not within the tolerance range, it means that the negative terminal current flowing through the negative relay is relatively small, and it can be determined that the negative relay is in a sticking state.

[0094] On the other hand, this embodiment also discloses a state detection method for a relay. Specifically, the specific implementation process of the state detection method is shown in FIG. Figure 2 , mainly including steps 201 to 203, the steps are:

[0095] Step 201: Apply a constant current to the positive relay connected in series to the positive end of the bus and the negative relay connected in series to the negative end of the bus.

[0096] In this embodiment, this step mainly includes: first applying the constant current to the positive pole relay to obtain the positive end current flowing through the positive pole relay in the positive end of the busbar; obtaining the positive end difference between the positive end current and the constant current; when the positive end difference is within a preset tolerance range, applying the constant current to the negative pole relay.

[0097] In this embodiment, this step first applies a constant current to the positive relay based on the circuit loop to perform a preliminary current loop status check. During this status check, if the difference between the current of the positive relay and the constant current is within the tolerance range, it indicates that the current flowing through the positive relay is relatively large, and a preliminary judgment can be made that the positive relay is stuck. In this case, in order to detect the negative relay, a constant current can be applied to the negative relay for status check.

[0098] Step 202: Obtain the positive terminal current flowing through the positive relay at the positive terminal of the bus and the negative terminal current flowing through the negative relay at the negative terminal of the bus.

[0099] Step 203: respectively obtaining comparison results of the positive terminal current, the negative terminal current, and the constant current, to determine the states of the positive electrode relay and the negative electrode relay according to the comparison results.

[0100] In this embodiment, this step mainly includes: when the positive end difference is within a preset tolerance range, obtaining the negative end current flowing through the negative pole relay in the negative end of the busbar, and obtaining the negative end difference between the negative end current and the constant current; when the negative end difference is not within the tolerance range, determining that the state of the positive pole relay is stuck and the state of the negative pole relay is disconnected; when the negative end difference is within the tolerance range, determining that the states of the positive pole relay and the negative pole relay are stuck.

[0101] When the positive end difference is not within a preset tolerance range, the negative end current flowing through the negative pole relay in the negative end of the bus is obtained, and the negative end difference between the negative end current and the constant current is obtained; when the negative end difference is within the tolerance range, it is determined that the state of the positive pole relay is disconnected and the state of the negative pole relay is stuck; when the negative end difference is not within the tolerance range, it is determined that the states of the positive pole relay and the negative pole relay are disconnected.

[0102] In this embodiment, this step uses a constant current that is not affected by external voltage as a standard to obtain the difference between the negative end current flowing through the negative pole relay and the constant current to determine the magnitude of the negative end current currently flowing through the negative pole relay, thereby accurately identifying the state of the negative pole relay.

[0103] Reference Figure 1 and Figure 2In a relay status detection device and method provided in this embodiment, the device is provided with a constant current source circuit to apply an undisturbed constant current to a positive relay connected in series to the positive end of a bus and a negative relay connected in series to the negative end of the bus, respectively, so as to avoid interference from external voltage through the constant current source circuit. Then, after the constant current is applied, the positive end current flowing through the positive relay and the negative end current flowing through the negative relay are obtained. Then, the positive end current and the negative end current are compared with the constant current to accurately detect the status of the positive relay and the negative relay.

[0104] Example 2

[0105] With the advancement of technology, electric vehicles and hybrid vehicles have become increasingly popular transportation options. Both electric and hybrid vehicles primarily utilize batteries as a power source to drive electric motors, generating power for starting. To prevent the battery from suddenly supplying excessive energy to the motor, potentially damaging it, existing vehicles use relays as switching devices connecting the battery and motor. These relays control the battery's energy supply to the motor, ensuring stable and safe driving. Therefore, accurately monitoring the relay's status is crucial for ensuring stable and safe vehicle operation.

[0106] In the prior art, the voltage across the relay is obtained, and the state of the relay is detected based on the consistency of the voltage across the relay. However, when the external voltage is close to or equal to the battery voltage, the existing detection scheme cannot accurately determine the state of the relay.

[0107] In order to solve the above technical problems, a relay state detection device is provided in this embodiment. The state detection device places a constant current source at the positive and negative ends of the high-voltage bus, and then detects the current in the bus. Under the condition that the internal and external voltages are equal, the relay state can also be correctly diagnosed.

[0108] Specifically, in this embodiment, the relay state detection device includes a first constant current source circuit, a second constant current source circuit, a first current acquisition device, a second current acquisition device, and a central control device. The first constant current source circuit and the second constant current source circuit are respectively connected to the central control device by signal, so that the central control device controls the first constant current source circuit and the second constant current source circuit to apply a constant current to the positive relay connected in series to the positive end of the bus and the negative relay connected in series to the negative end of the bus, respectively; the input end of the positive relay and the input end of the negative relay are respectively connected to the output end of the first constant current source circuit and the output end of the second constant current source circuit; the output end of the positive relay and the output end of the negative relay are respectively connected to the input end of the first constant current source circuit and the input end of the second constant current source circuit;

[0109] The first current acquisition device and the second current acquisition device are respectively connected to the central control device for signal connection, and are used to obtain the positive current of the positive end of the busbar and the negative current of the negative end of the busbar, and send the positive current and the negative current to the central control device; wherein the output end of the positive pole relay and the output end of the negative pole relay are respectively connected to the input end of the first current acquisition device and the second current acquisition device; the input end of the first constant current source circuit and the second constant current source circuit are respectively connected to the output end of the first current acquisition device and the second current acquisition device;

[0110] The central control device receives the positive terminal current and the negative terminal current, and compares the positive terminal current and the negative terminal current with the constant current respectively, so as to determine the status of the positive electrode relay and the negative electrode relay according to the comparison results.

[0111] In certain implementations of this embodiment, taking a relay connected in series between a power source and a charger as an example, the relay is detected using the relay state detection device provided in this embodiment. The connection circuit diagram of the relay state detection and the relay is as follows: Figure 3 shown.

[0112] Specifically, refer to Figure 3The relay state detection device includes a first constant current source circuit 301, a second constant current source circuit 302, a first current collection device 303, and a second current collection device 304. The first constant current source circuit 301 is connected to both ends of a positive relay S1 located at the positive end of the charger's busbar, while the second constant current source circuit 302 is connected to both ends of a negative relay S2 located at the negative end of the charger's busbar, to provide stable constant currents to S1 and S2, respectively. The first current collection device 303 is connected in series between the fixed end of S1 and the input end of the constant current source to collect the positive current flowing through S1. Similarly, the second current collection device 304 is connected in series between the fixed end of S2 and the input end of the constant current source to collect the negative current flowing through S2.

[0113] Further, refer to Figure 3 To ensure that the constant current source circuit provides a stable current to S1 and S2, a constant current source, a first switch K1 and a first diode D1 are provided in the first constant current source circuit 301. Similarly, a constant current source, a second switch K2 and a second diode D2 are provided in the second constant current source circuit 302. Figure 3 As shown, the input end of the first switch K1 in the first constant current source circuit 301 is connected to the output end of the constant current source; the fixed end of the positive relay S1 is connected to the input end of the constant current source. The active end of the first switch K1 is electrically connected to the input end of the first diode D1; the output end of the first diode D1 is electrically connected to the active end of the positive relay S1. Similarly, the input end of the second switch K2 in the second constant current source circuit 302 is connected to the output end of the constant current source; the fixed end of the negative relay S2 is connected to the input end of the constant current source. The active end of the second switch K2 is electrically connected to the input end of the second diode D2; the output end of the second diode D2 is electrically connected to the active end of the negative relay S2.

[0114] In such Figure 3 As shown, after the first constant current source circuit 301 and the second constant current source circuit 302 are connected to both ends of the positive relay S1 and the negative relay S2 respectively, the central control device performs the following steps: Figure 4 The steps shown are to obtain the status detection results of the positive relay S1 and the negative relay S2. Specifically, the detection steps include:

[0115] Step 401: Close K1, open K2, obtain a first current A1 collected by a first current collection device, and determine whether to open K1 and close K2 based on A1 and the current output by the constant current source.

[0116] In this embodiment, this step mainly includes: controlling the first switch K1 to be closed and the second switch K2 to be opened by the central control device, and then obtaining the first current A1 fed back by the first current acquisition device to determine whether to switch the state of the switch based on A1 and the current output by the constant current source.

[0117] Specifically, in some implementations of this embodiment, the constant current source is set to output a fixed current of 1A. When K1 is closed and K2 is open, analysis of the states of S1 and S2 shows that the S1 and S2 switches have the following four possible states: S1 is open, S2 is open; S1 is open, S2 is closed; S1 is closed, S2 is open; S1 is closed, S2 is open; S1 is closed, S2 is closed.

[0118] When S1 is open and S2 is open, the constant current output has no return path, and A1 and A2 are both 0; when S1 is open and S2 is closed, the current path is as follows Figure 5 As shown, A1=0, A2=1A; when S1 is closed and S2 is open, the current path is as follows Figure 6 As shown, A1=1A, A2=0; and when S1 is closed and S2 is closed, the current path is as follows Figure 7 As shown, at this time, assuming that the equivalent resistance on path 1 is R1 and the equivalent resistance on path 2 is R2, the equivalent circuit is as follows Figure 8 As shown, for actual application, R1 is the internal resistance of a short copper busbar, R2 is the sum of the internal resistance of the longer copper busbar, the internal resistance of the battery pack, and the internal resistance of the charger. R1 is smaller than R2, so the corresponding current A1 is greater than A2. Therefore, in general, the judgment threshold can be set to half of the constant current source output current, that is, in the following example: Figure 8 In the example shown, half of the 1 A current is 0.5 A, where A1 > 0.5 A and A2 < 0.5 A. Preferably, this threshold value can be adjusted according to the equivalent R1 and R2 values ​​in the actual electrical connection.

[0119] Referring to the above analysis of the switch states of S1 and S2 and the corresponding currents, it can be seen that in this embodiment, after K1 is closed and K2 is opened, when the value of the first current A1 fed back by the first current acquisition device is less than the threshold value, i.e., 0.5A, it can be determined that the states of S1 and S2 are only in two states: S1 open, S2 open, or S1 open, S2 closed. At this time, there is no need to switch the switch states of K1 and K2.

[0120] When the value of the first current A1 fed back by the first current acquisition device is greater than or equal to the threshold value, i.e., 0.5A, it can be determined that the states of S1 and S2 are only S1 closed and S2 open or S1 closed and S2 closed. At this time, it is necessary to switch K1 open and K2 closed.

[0121] Step 402: When it is determined that K1 is not opened and K2 is not closed, the second current A2 fed back by the second current acquisition device is obtained, so as to obtain the corresponding states of the positive relay S1 and the negative relay S2 according to A2 and the constant current output by the constant current source.

[0122] In this embodiment, this step mainly includes: setting the current threshold according to the size of the constant current. Specifically, referring to the above steps, when the constant current is set to 1A, the current threshold is set to half of the constant current, that is, 0.5A, according to the actual electrical conditions.

[0123] A comparison result between the second current A2 and the current threshold is obtained, and the corresponding states of S1 and S2 are determined based on the comparison result. Specifically, when A2 is greater than or equal to 0.5A, the central control device determines that S1 is disconnected and S2 is stuck; and when A2 is less than 0.5A, the central control device determines that S1 is disconnected and S2 is disconnected.

[0124] Step 403: When it is determined that K1 is opened and K2 is closed, the second current A2 fed back by the second current acquisition device is obtained, so as to obtain the corresponding states of the positive relay S1 and the negative relay S2 according to A2 and the constant current output by the constant current source.

[0125] In this embodiment, this step mainly includes: setting the current threshold according to the size of the constant current. Specifically, referring to the above steps, when the constant current is set to 1A, the current threshold is set to half of the constant current, that is, 0.5A, according to the actual electrical conditions.

[0126] Obtaining a comparison result between the second current A2 and the current threshold, and determining the corresponding states of S1 and S2 based on the comparison result. Specifically, when A2 is greater than or equal to 0.5A, the central control device determines that S1 and S2 are stuck; and when A2 is less than 0.5A, the central control device determines that S1 is stuck and S2 is disconnected.

[0127] This embodiment provides a relay status detection device, which provides a constant current to the relay by placing a low-power constant current source at the positive and negative ends of the high-voltage bus, thereby ensuring that the relay status detection is not affected by the external voltage. Furthermore, by detecting the current in the bus, the relay status can be quickly and accurately determined under the condition that the internal and external voltages are equal, thereby indicating system reliability.

[0128] The specific embodiments described above further illustrate the objectives, technical solutions, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A relay state detection device, characterized in that: It includes a constant current source circuit, a current sensor and a main controller; The constant current source circuit is connected to the main controller signal so that the main controller controls the constant current source circuit to apply a constant current to the positive relay connected in series to the positive end of the bus and the negative relay connected in series to the negative end of the bus; wherein the input end of the positive relay and the input end of the negative relay are connected to the output end of the constant current source circuit respectively; the output end of the positive relay and the output end of the negative relay are connected to the input end of the constant current source circuit respectively; The current sensor is connected to the main controller signal, and is used to obtain the positive end current of the positive end of the busbar and the negative end current of the negative end of the busbar, and send the positive end current and the negative end current to the main controller; wherein the output end of the positive pole relay and the output end of the negative pole relay are respectively connected to the input end of the current sensor; the input end of the constant current source circuit is connected to the output end of the current sensor; The main controller receives the positive terminal current and the negative terminal current, and compares the positive terminal current and the negative terminal current with the constant current respectively, so as to determine the states of the positive electrode relay and the negative electrode relay according to the comparison results.

2. A relay state detection device according to claim 1, characterized in that: The constant current source circuit comprises a constant current source, a first switch, a second switch, a first diode and a second diode; The input end of the first switch and the input end of the second switch are electrically connected to the output end of the constant current source respectively; the output end of the positive relay and the output end of the negative relay are electrically connected to the input end of the constant current source; The output end of the first switch is electrically connected to the input end of the first diode; the output end of the second switch is electrically connected to the input end of the second diode; The output end of the first diode is electrically connected to the input end of the positive relay; The output end of the second diode is electrically connected to the input end of the negative relay.

3. A relay state detection device according to claim 2, characterized in that: The main controller controls the first switch to close and controls the second switch to open, so as to apply the constant current to the positive relay through the constant current source; The main controller receives the positive end current of the positive end of the busbar sent by the current sensor, and obtains the positive end difference between the positive end current and the constant current; When the main controller determines that the positive end difference is within a preset tolerance range, the main controller controls the first switch to be opened and controls the second switch to be closed, so as to apply the constant current to the negative relay through the constant current source.

4. A relay state detection device according to claim 3, characterized in that: The main controller is also used to receive the negative end current of the negative end of the busbar sent by the current sensor, and obtain the negative end difference between the negative end current and the constant current; When the main controller determines that the negative terminal difference is not within the tolerance range, the main controller determines that the state of the positive relay is adhered and the state of the negative relay is disconnected.

5. A relay state detection device according to claim 4, characterized in that: When the main controller determines that the negative terminal difference is within the tolerance range, the main controller determines that the states of the positive relay and the negative relay are stuck.

6. A relay state detection device according to claim 3, characterized in that: When the main controller determines that the positive end difference is not within a preset tolerance range, the main controller receives the negative end current of the negative end of the busbar sent by the current sensor, and obtains the negative end difference between the negative end current and the constant current; The main controller determines that the state of the positive relay is disconnected and the state of the negative relay is adhered after determining that the negative terminal difference is within the tolerance range.

7. A relay state detection device according to claim 6, characterized in that: When determining that the negative terminal difference is not within the tolerance range, the main controller determines that the states of the positive relay and the negative relay are disconnected.

8. A method for detecting the state of a relay, characterized in that: include: A constant current is applied to the positive relay connected in series to the positive end of the bus and the negative relay connected in series to the negative end of the bus respectively; Acquire the positive terminal current flowing through the positive relay at the positive terminal of the busbar and the negative terminal current flowing through the negative relay at the negative terminal of the busbar; The comparison results of the positive terminal current, the negative terminal current and the constant current are respectively obtained to determine the states of the positive electrode relay and the negative electrode relay according to the comparison results.

9. A method for detecting a state of a relay according to claim 8, characterized in that: The method of applying a constant current to the positive relay connected in series to the positive end of the bus and the negative relay connected in series to the negative end of the bus respectively comprises: Firstly, the constant current is applied to the positive relay to obtain the positive terminal current flowing through the positive relay at the positive terminal of the busbar; Obtaining a positive end difference between the positive end current and the constant current; When the positive terminal difference is within a preset tolerance range, the constant current is applied to the negative electrode relay.

10. A method for detecting a state of a relay according to claim 9, characterized in that: The step of respectively obtaining comparison results of the positive terminal current, the negative terminal current and the constant current to determine the states of the positive electrode relay and the negative electrode relay according to the comparison results includes: Obtaining a negative terminal current flowing through the negative electrode relay at the negative terminal of the busbar, and obtaining a negative terminal difference between the negative terminal current and the constant current; When the negative terminal difference is not within the tolerance range, it is determined that the state of the positive relay is adhered and the state of the negative relay is disconnected.

11. A method for detecting a state of a relay according to claim 10, characterized in that: The step of respectively obtaining comparison results of the positive terminal current, the negative terminal current and the constant current to determine the states of the positive electrode relay and the negative electrode relay according to the comparison results includes: When the negative terminal difference is within the tolerance range, it is determined that the states of the positive relay and the negative relay are stuck.

12. A method for detecting a state of a relay according to claim 9, characterized in that: The step of respectively obtaining comparison results of the positive terminal current, the negative terminal current and the constant current to determine the states of the positive electrode relay and the negative electrode relay according to the comparison results includes: When the positive terminal difference is not within a preset tolerance range, obtaining a negative terminal current flowing through the negative pole relay in the negative terminal of the bus, and obtaining a negative terminal difference between the negative terminal current and the constant current; When the negative terminal difference is within the tolerance range, it is determined that the state of the positive relay is disconnected and the state of the negative relay is adhered.

13. A method for detecting a state of a relay according to claim 12, characterized in that: The step of respectively obtaining comparison results of the positive terminal current, the negative terminal current and the constant current to determine the states of the positive electrode relay and the negative electrode relay according to the comparison results includes: When the negative terminal difference is not within the tolerance range, it is determined that the states of the positive relay and the negative relay are disconnected.

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