Relay state detection apparatus and method

Abstract

A relay state detection apparatus and method. The apparatus comprises a constant current source circuit (101), a current sensor (102) and a master controller (103); the master controller (103) controls the constant current source circuit (101) to respectively apply constant currents to a positive relay connected in series to a positive end of a bus and a negative relay connected in series to a negative end of the bus; the current sensor (102) is in signal connection to the master controller (103), 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 to the master controller (103) the positive end current and the negative end current; the master controller (103) receives the positive end current and the negative end current, and separately compares the positive end current and the negative end current with a constant current, so as to determine the states of the positive relay and the negative relay on the basis of comparison results, thereby improving the accuracy and efficiency of relay state detection.

Description

A relay status detection device and method

[0001] Cross-references to related applications

[0002] This application claims the benefit of Chinese Patent Application No. 202411613820.8, filed on November 12, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of electric vehicle technology, and more specifically, to a relay condition diagnosis device and method. Background Technology

[0004] In electric vehicles and large-scale energy storage battery systems, voltages often reach hundreds of volts. Therefore, high-voltage power supply safety has become a crucial area of ​​research and development in high-voltage battery systems. To address this, engineers employ high-voltage relays throughout the battery's operating circuitry to maintain normal circuit operation.

[0005] Under normal conditions, the high-voltage relays in the circuit maintain circuit safety by opening and closing normally. However, if a relay malfunctions, the circuit will be at risk of high voltage.

[0006] In response, existing technicians have developed various technologies for relay fault diagnosis to ensure circuit safety through fault repair. Current relay diagnostic methods often determine faults by comparing the voltages at the ends of the relay. However, this method becomes ineffective when the external voltage is close to or equal to the battery voltage, failing to accurately determine the relay's condition based solely on the voltage across the terminals.

[0007] Application content

[0008] To address the aforementioned technical problems, this application discloses a relay status detection device and method to overcome the deficiencies in the prior art and improve the accuracy of relay status detection.

[0009] To achieve the above objectives, this application discloses a relay state detection device, including a constant current source circuit, a current sensor, and a main controller;

[0010] The constant current source circuit is signal-connected to the main controller. The main controller controls the constant current source circuit to apply a constant current to the positive relay connected in series at the positive terminal of the bus and the negative relay connected in series at the negative terminal of the bus. The input terminals of the positive and negative relays are respectively connected to the output terminals of the constant current source circuit. The output terminals of the positive and negative relays are respectively connected to the input terminals of the constant current source circuit via the current sensor. The current sensor is also signal-connected to the main controller and is used to acquire the positive current at the positive terminal of the bus and the negative current at the negative terminal of the bus, and send the positive and negative currents to the main controller. The output terminals of the positive and negative relays are respectively connected to the input terminals of the current sensor. The input terminal of the constant current source circuit is connected to the output terminal of the current sensor.

[0011] The main controller is used to receive the positive terminal current and the negative terminal current, and compare the positive terminal current and the negative terminal current with the constant current respectively, so as to determine the state of the positive relay and the negative relay based on the comparison result.

[0012] This application discloses a relay state detection device, which sets up a constant current source circuit to apply an undisturbed constant current to a positive relay connected in series at the positive terminal of a busbar and a negative relay connected in series at the negative terminal of the busbar, so as to avoid interference from external voltage through the constant current source circuit. Then, it obtains the current flowing through the positive terminal of the positive relay and the current flowing through the negative terminal of the negative relay after the constant current is applied, and compares the positive terminal current and the negative terminal current with the constant current to accurately detect the state of the positive relay and the negative relay.

[0013] 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;

[0014] The input terminals of the first switch and the second switch are electrically connected to the output terminal of the constant current source, respectively; the output terminals of the positive relay and the negative relay are electrically connected to the input terminal of the constant current source.

[0015] The output terminal of the first switch is electrically connected to the input terminal of the first diode; the output terminal of the second switch is electrically connected to the input terminal of the second diode.

[0016] The output terminal of the first diode is electrically connected to the input terminal of the positive relay;

[0017] The output terminal of the second diode is electrically connected to the input terminal of the negative relay.

[0018] This application incorporates a constant current source to provide a stable, constant current, avoiding the influence of external voltage and improving detection accuracy. A first switch and a second switch are configured to control the order in which current is applied to the positive and negative relays, allowing for accurate determination of the relay states based on this order. A diode is included to protect the constant current source from damage caused by reverse voltage flow.

[0019] As a preferred example, the main controller is used to control the first switch to close and the second switch to open, so that the constant current source applies the constant current to the positive relay;

[0020] The main controller is used to receive the positive terminal current of the busbar sent by the current sensor, and to obtain the positive terminal current difference between the positive terminal current and the positive terminal current of the constant current.

[0021] The main controller is used to control the first switch to open and the second switch to close when it is determined that the positive terminal difference is within a preset tolerance range, so that the constant current source applies the constant current to the negative relay.

[0022] Based on the circuit loop formed by the constant current source circuit, the positive relay, and the negative relay, this application shows that by first closing the first switch, a constant current is applied to the positive relay to achieve preliminary current loop state detection. During the state detection process, if the difference between the current of the positive relay and the constant current is detected to be 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. At this point, in order to detect the negative relay, the second switch can be closed, the first switch opened, and a constant current can be applied to the negative relay for state detection.

[0023] As a preferred example, the main controller is further configured to receive the negative terminal current of the bus negative terminal sent by the current sensor, and obtain the negative terminal difference between the negative terminal current and the constant current.

[0024] The main controller is also used to determine that the state of the positive relay is stuck and the state of the negative relay is open when it is determined that the negative terminal difference is not within the tolerance range.

[0025] This application uses a constant current, unaffected by external voltage, as a standard to obtain the difference between the negative terminal current flowing through the negative relay and the constant current, thereby determining the magnitude of the current flowing through the negative terminal of the negative relay and accurately identifying the state of the negative relay. When the difference between the negative terminals is not within the tolerance range, it indicates that the current flowing through the negative terminal of the negative relay is relatively small, and the negative relay can be determined to be in an open state.

[0026] As a preferred example, the main controller is further configured to determine that the state of the positive relay and the negative relay is sticky when the negative terminal difference is determined to be within the tolerance range.

[0027] When this application determines that the negative terminal difference is not within the tolerance range, it indicates 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 sticky state.

[0028] As a preferred example, the main controller is further configured to receive the negative terminal current of the negative terminal of the bus sent by the current sensor and obtain the negative terminal difference between the negative terminal current and the constant current when it is determined that the positive terminal difference is not within a preset tolerance range.

[0029] The main controller is also used to determine, when the negative terminal difference is within the tolerance range, that the state of the positive relay is open and the state of the negative relay is stuck.

[0030] In this application, during the process of applying a constant current to the positive relay when the first switch is closed to achieve preliminary current loop state 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 small, and it can be preliminarily determined that the positive relay is open. At this point, to detect the negative relay, it is only necessary to obtain the negative terminal current of the negative relay for state detection. Specifically, 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 it can be determined that the negative relay is in a stuck state.

[0031] As a preferred example, the main controller is further configured to determine that the state of the positive relay and the negative relay is open when it is determined that the negative terminal difference is not within the tolerance range.

[0032] When this application determines that the negative terminal difference is not within the tolerance range, it indicates that the negative terminal current flowing through the negative relay is relatively small, and it can be determined that the negative relay is in an open state.

[0033] As a preferred example, the constant current source includes a first constant current source and a second constant current source;

[0034] The input terminal of the first switch is electrically connected to the output terminal of the first constant current source, and the input terminal of the second switch is electrically connected to the output terminal of the second constant current source; the output terminal of the positive relay is electrically connected to the input terminal of the first constant current source through the current sensor, and the output terminal of the negative relay is electrically connected to the input terminal of the second constant current source through the current sensor.

[0035] As a preferred example, the current sensor includes a first current sensor and a second current sensor;

[0036] The output terminal of the positive relay is connected to the input terminal of the first current sensor, and the output terminal of the negative relay is connected to the input terminal of the second current sensor; the input terminal of the first constant current source circuit is connected to the output terminal of the first current sensor, and the input terminal of the second constant current source circuit is connected to the output terminal of the second current sensor.

[0037] On the other hand, this application also discloses a relay state detection method, including:

[0038] A constant current is applied to the positive relay connected in series at the positive terminal of the busbar and the negative relay connected in series at the negative terminal of the busbar, respectively.

[0039] Obtain the positive terminal current flowing through the positive relay in the positive terminal of the busbar and the negative terminal current flowing through the negative relay in the negative terminal of the busbar;

[0040] The positive terminal current, the negative terminal current, and the constant current are compared respectively to determine the state of the positive relay and the negative relay based on the comparison results.

[0041] This application discloses a relay state detection method, which involves applying constant currents to a positive relay connected in series at the positive terminal of a busbar and a negative relay connected in series at the negative terminal of the busbar to avoid interference from external voltage. The method then obtains the current flowing through the positive terminal of the positive relay and the current flowing through the negative terminal of the negative relay after the constant current is applied. By comparing the positive and negative currents with the constant current, the state of the positive and negative relays can be accurately detected.

[0042] As a preferred example, applying constant current to the positive relay connected in series at the positive terminal of the busbar and the negative relay connected in series at the negative terminal of the busbar respectively includes:

[0043] First, apply the constant current to the positive relay to obtain the positive terminal current flowing through the positive relay in the positive terminal of the bus;

[0044] Obtain the difference between the positive terminal current and the positive terminal current of the constant current;

[0045] When the positive terminal difference is within the preset tolerance range, the constant current is applied to the negative terminal relay.

[0046] This application first applies a constant current to the positive relay to achieve preliminary current loop state detection. During the state detection process, when the difference between the current of the positive relay and the constant current is detected 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 state detection.

[0047] As a preferred example, the step of obtaining the comparison results of the positive terminal current, the negative terminal current, and the constant current, respectively, to determine the states of the positive relay and the negative relay based on the comparison results, includes:

[0048] Obtain the negative terminal current flowing through the negative relay in the negative terminal of the busbar, and obtain the negative terminal difference between the negative terminal current and the negative terminal of the constant current;

[0049] When the negative terminal difference is not within the tolerance range, the state of the positive relay is determined to be stuck and the state of the negative relay is determined to be open.

[0050] This application uses a constant current, unaffected by external voltage, as a standard to obtain the difference between the negative terminal current flowing through the negative relay and the constant current, thereby determining the magnitude of the current flowing through the negative terminal of the negative relay and accurately identifying the state of the negative relay. When the difference between the negative terminals is not within the tolerance range, it indicates that the current flowing through the negative terminal of the negative relay is relatively small, and the negative relay can be determined to be in an open state.

[0051] As a preferred example, after obtaining the difference between the negative terminal current and the negative terminal of the constant current, the method further includes:

[0052] When the negative terminal difference is within the tolerance range, the state of the positive relay and the negative relay is determined to be sticky.

[0053] When this application determines that the negative terminal difference is not within the tolerance range, it indicates 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 sticky state.

[0054] As a preferred example, after obtaining the difference between the positive terminal current and the positive terminal of the constant current, the method further includes:

[0055] When the positive terminal difference is not within the preset tolerance range, the negative terminal current flowing through the negative relay in the negative terminal of the bus is obtained, and the negative terminal difference between the negative terminal current and the constant current is obtained.

[0056] When the negative terminal difference is within the tolerance range, the state of the positive relay is determined to be open and the state of the negative relay is determined to be stuck.

[0057] In this application, during the initial current loop state detection process of applying a constant current to the positive relay, 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 small, and the positive relay can be preliminarily determined to be open. In this case, to detect the negative relay, it is only necessary to obtain the negative terminal current of the negative relay for state 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.

[0058] As a preferred example, after obtaining the difference between the negative terminal current and the negative terminal of the constant current, the method further includes:

[0059] When the negative terminal difference is not within the tolerance range, the state of the positive relay and the negative relay is determined to be open.

[0060] When this application determines that the negative terminal difference is not within the tolerance range, it indicates that the negative terminal current flowing through the negative relay is relatively small, and it can be determined that the negative relay is in an open state. Attached Figure Description

[0061] Figure 1: A schematic diagram of the structure of a relay state detection device disclosed in an embodiment of this application;

[0062] Figure 2: A schematic flowchart of a relay state detection method disclosed in an embodiment of this application;

[0063] Figure 3: A schematic diagram of the structure of a relay state detection circuit disclosed in another embodiment of this application;

[0064] Figure 4: A schematic diagram of a relay state detection process disclosed in another embodiment of this application;

[0065] Figure 5: A schematic diagram of the current path corresponding to the closing of the first switch disclosed in another embodiment of this application;

[0066] Figure 6: A schematic diagram of another current path corresponding to the closing of the first switch disclosed in another embodiment of this application;

[0067] Figure 7: A schematic diagram of another current path corresponding to the closing of the first switch disclosed in another embodiment of this application;

[0068] Figure 8: A schematic diagram of the current path of the equivalent circuit corresponding to the closing of the first switch disclosed in another embodiment of this application. Detailed Implementation

[0069] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0070] Example 1

[0071] This embodiment discloses a relay status detection device. Specifically, the structure of the status detection device can be seen with reference to Figure 1, and it mainly includes a constant current source circuit 101, a current sensor 102, and a main controller 103.

[0072] As shown in Figure 1, the constant current source circuit 101 is signal-connected to the main controller 103. The main controller 103 controls the constant current source circuit 101 to apply constant current to the positive relay connected in series at the positive end of the bus and the negative relay connected in series at the negative end of the bus. The input terminals of the positive and negative relays are respectively connected to the output terminals of the constant current source circuit 101. The output terminals of the positive and negative relays are respectively connected to the input terminals of the constant current source circuit 101 via the current sensor 102. The current sensor 102 is also signal-connected to the main controller 103, used to acquire the positive current at the positive end of the bus and the negative current at the negative end of the bus, and send the positive and negative currents to the main controller 103. The output terminals of the positive and negative relays are respectively connected to the input terminals of the current sensor 102. The input terminal of the constant current source circuit 101 is connected to the output terminal of the current sensor 102.

[0073] The main controller 103 is used to receive the positive terminal current and the negative terminal current, and compare the positive terminal current and the negative terminal current with the constant current respectively, so as to determine the state of the positive relay and the negative relay according to the comparison result.

[0074] Specifically, in order to obtain the state detection result of the relay through the state detection device shown in Figure 1, the output terminal of the constant current source circuit 101 is respectively connected to the input terminal of the positive relay connected in series with the positive end of the bus and the input terminal of the negative relay connected in series with the negative end of the bus; while the input terminal of the constant current source circuit 101 is respectively connected to the output terminal of the positive relay connected in series with the positive end of the bus and the output terminal of the negative relay connected in series with the negative end of the bus.

[0075] Furthermore, in order to obtain the current across the positive relay and the negative relay through the current sensor 102, the input terminal of the current sensor 102 is connected to the output terminal of the positive relay and the output terminal of the negative relay, respectively.

[0076] In some embodiments of this example, 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.

[0077] Furthermore, in order to obtain the states corresponding to the positive relay and the negative relay more accurately, a first switch and a second switch can be set in the constant current source circuit to control the order in which the constant current source applies current to the positive relay and the negative relay.

[0078] 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 provided in the constant current source circuit to protect the constant current source and prevent the terminal voltage from backflowing and damaging the constant current source.

[0079] Specifically, referring to the functional settings of the constant current source, the first switch, the second switch, the first diode, and the second diode described above, the connection relationships of the constant current source, the first switch, the second switch, the first diode, and the second diode are as follows: the input terminals of the first switch and the second switch are electrically connected to the output terminal of the constant current source; the output terminals of the positive relay and the negative relay are electrically connected to the input terminal of the constant current source; the output terminal of the first switch is electrically connected to the input terminal of the first diode; the output terminal of the second switch is electrically connected to the input terminal of the second diode; the output terminal of the first diode is electrically connected to the input terminal of the positive relay; and the output terminal of the second diode is electrically connected to the input terminal of the negative relay.

[0080] In some embodiments of this example, the constant current source includes a first constant current source and a second constant current source;

[0081] The input terminal of the first switch is electrically connected to the output terminal of the first constant current source, and the input terminal of the second switch is electrically connected to the output terminal of the second constant current source; the output terminal of the positive relay is electrically connected to the input terminal of the first constant current source through the current sensor, and the output terminal of the negative relay is electrically connected to the input terminal of the second constant current source through the current sensor.

[0082] In some embodiments of this example, the current sensor includes a first current sensor and a second current sensor;

[0083] The output terminal of the positive relay is connected to the input terminal of the first current sensor, and the output terminal of the negative relay is connected to the input terminal of the second current sensor; the input terminal of the first constant current source circuit is connected to the output terminal of the first current sensor, and the input terminal of the second constant current source circuit is connected to the output terminal of the second current sensor.

[0084] In some embodiments of this example, referring to the structure of the constant current source circuit 101, and based on the main controller 103's control of the constant current source circuit 101 to apply current to the positive and negative relays in sequence to obtain the relay status detection results, it can be seen that the process by which the main controller 103 detects the relays includes the following steps:

[0085] S1: The main controller 103 controls the first switch to close and controls the second switch to open, so that the constant current source applies the constant current to the positive relay;

[0086] S2: The main controller 103 receives the positive terminal current of the bus positive terminal sent by the current sensor 102, and obtains the positive terminal difference between the positive terminal current and the constant current.

[0087] S3: When the main controller 103 determines that the positive terminal difference is within a preset tolerance range, it controls the first switch to open and controls the second switch to close, so that the constant current source applies the constant current to the negative relay.

[0088] In steps S1 to S3, based on the fact that the positive relay is connected to the positive end of the busbar and the negative relay is connected to the negative end of the busbar, in order to form a current loop for detection, the main controller 103 first closes the first switch to apply a constant current to the positive relay to achieve preliminary current loop status detection. During the status detection process, when it is detected that 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 large, and it can be preliminarily determined that the positive relay is stuck. At this time, in order to detect the negative relay, the second switch can be closed and the first switch opened to apply a constant current to the negative relay for status detection.

[0089] Furthermore, based on the execution condition of step S3 being that the positive terminal difference is within a preset tolerance range, when the positive terminal difference is not within the preset tolerance range, the main controller 103 executes the following steps:

[0090] S4: When the main controller 103 determines that the positive terminal difference is not within the preset tolerance range, it receives the negative terminal current of the negative terminal of the bus sent by the current sensor 102, and obtains the negative terminal difference between the negative terminal current and the constant current.

[0091] S5: When the main controller 103 determines that the negative terminal difference is within the tolerance range, it determines that the positive relay is in the open state and the negative relay is in the stuck state.

[0092] In steps S4 and S5 above, during the process of applying a constant current to the positive relay by closing the first switch to achieve preliminary current loop state 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 small, and it can be preliminarily determined that the positive relay is open. At this time, to detect the negative relay, it is only necessary to obtain the negative terminal current of the negative relay for state detection. Wherein, 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 it can be determined that the negative relay is in a stuck state.

[0093] Furthermore, based on the execution condition of step S5 being that the positive terminal difference is not within the preset tolerance range and the negative terminal difference is within the tolerance range, when the positive terminal difference is not within the preset tolerance range and the negative terminal difference is not within the tolerance range, the main controller 103 executes the following steps:

[0094] S6: When the main controller 103 determines that the negative terminal difference is not within the tolerance range, it determines that the positive relay and the negative relay are in the open state.

[0095] In step S6, if it is determined that the negative terminal difference is not within the tolerance range, it indicates that the negative terminal current flowing through the negative relay is relatively small, and it can be determined that the negative relay is in the open state.

[0096] Further, 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:

[0097] S7: The main controller 103 receives the negative terminal current of the bus negative terminal sent by the current sensor 102, and obtains the negative terminal difference between the negative terminal current and the constant current.

[0098] S8: When the main controller 103 determines that the negative terminal difference is not within the tolerance range, it determines that the positive relay is stuck and the negative relay is disconnected.

[0099] In steps S7 and S8, a constant current unaffected by external voltage is used as a standard to obtain the difference between the negative terminal current flowing through the negative relay and the constant current. This difference is used to determine the magnitude of the current flowing through the negative terminal of the negative relay, allowing for accurate identification of the relay's state. When the negative terminal difference is outside the tolerance range, it indicates that the current flowing through the negative terminal of the negative relay is relatively small, and the relay can be determined to be in an open state.

[0100] Furthermore, based on the execution condition of step S8 being that the negative terminal difference is not within a preset tolerance range, when the negative terminal difference is within the preset tolerance range, the main controller 103 executes the following steps:

[0101] S9: When the main controller 103 determines that the negative terminal difference is within the tolerance range, it determines that the positive relay and the negative relay are stuck together.

[0102] In step S9, if it is determined that the negative terminal difference is not within the tolerance range, it indicates 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 sticky state.

[0103] On the other hand, this embodiment also discloses a relay state detection method. Specifically, the specific implementation flow of the state detection method is shown in Figure 2, mainly including steps 201 to 203, which are as follows:

[0104] Step 201: Apply a constant current to the positive relay connected in series at the positive terminal of the busbar and the negative relay connected in series at the negative terminal of the busbar, respectively.

[0105] In this embodiment, the step mainly includes: first applying the constant current to the positive relay to obtain the positive terminal current flowing through the positive relay in the positive terminal of the bus; obtaining the positive terminal difference between the positive terminal current and the constant current; and when the positive terminal difference is within a preset tolerance range, applying the constant current to the negative relay.

[0106] In this embodiment, this step involves applying a constant current to the positive relay based on the circuit loop to achieve preliminary current loop state detection. During the state detection process, if the difference between the current of the positive relay and the constant current is found 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 point, in order to detect the negative relay, a constant current can be applied to the negative relay for state detection.

[0107] Step 202: Obtain the positive terminal current flowing through the positive relay in the positive terminal of the busbar and the negative terminal current flowing through the negative relay in the negative terminal of the busbar.

[0108] Step 203: Obtain the comparison results of the positive terminal current, the negative terminal current and the constant current respectively, so as to determine the state of the positive relay and the negative relay based on the comparison results.

[0109] In this embodiment, the step mainly includes: when the positive terminal difference is within a preset tolerance range, obtaining the negative terminal current flowing through the negative relay in the negative terminal of the bus, and obtaining the negative terminal difference between the negative terminal current and the constant current; when the negative terminal difference is not within the tolerance range, determining that the state of the positive relay is stuck and the state of the negative relay is open; when the negative terminal difference is within the tolerance range, determining that the state of the positive relay and the negative relay is stuck.

[0110] When the positive terminal difference is not within the preset tolerance range, the negative terminal current flowing through the negative relay in the negative terminal of the bus is obtained, and the negative terminal difference between the negative terminal current and the constant current is obtained; when the negative terminal difference is within the tolerance range, the state of the positive relay is determined to be open and the state of the negative relay is determined to be stuck; when the negative terminal difference is not within the tolerance range, the state of the positive relay and the negative relay is determined to be open.

[0111] In this embodiment, this step uses a constant current unaffected by external voltage as a standard to obtain the difference between the negative terminal current flowing through the negative relay and the constant current, so as to determine the magnitude of the current flowing through the negative terminal of the negative relay and accurately identify the state of the negative relay.

[0112] Referring to Figures 1 and 2, in the relay state detection device and method provided in this embodiment, the device sets a constant current source circuit to apply an undisturbed constant current to the positive relay connected in series at the positive end of the bus and the negative relay connected in series at the negative end of the bus, so as to avoid interference from external voltage through the constant current source circuit, thereby obtaining the positive terminal current flowing through the positive relay and the negative terminal current flowing through the negative relay after the constant current is applied, and then comparing the positive terminal current and the negative terminal current with the constant current, the state of the positive relay and the negative relay can be accurately detected.

[0113] Example 2

[0114] With the development of technology, electric vehicles and hybrid vehicles have gradually become the preferred means of transportation for users. Both electric and hybrid vehicles primarily use batteries as a power source to drive an electric motor, thereby obtaining power for starting. During the process of the battery connecting to the electric motor to provide energy, to prevent the battery from suddenly supplying excessive energy to the motor and potentially damaging it, existing vehicles use relays as switching devices connecting the battery and the motor. These relays control the energy supply from the battery to the motor. Therefore, accurate detection of the relay's status is a crucial guarantee for the stable and safe operation of the vehicle.

[0115] In the prior art, the state of the relay is detected by acquiring the voltage across the two ends of the relay and then detecting the consistency of the voltage across the two ends. 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.

[0116] To solve the above-mentioned technical problems, this embodiment provides a relay status detection device. The status detection device places constant current sources at the positive and negative ends of the high-voltage bus and then detects the current in the bus. Under the condition that the voltages on the inner and outer sides are equal, the relay status can be correctly diagnosed.

[0117] Specifically, in this embodiment, the relay status 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 (i.e., a main controller). The first and second constant current source circuits are respectively signal-connected to the central control device, enabling the central control device to control the first and second constant current source circuits to apply constant currents to a positive relay connected in series at the positive terminal of the bus and a negative relay connected in series at the negative terminal of the bus, respectively. The input terminals of the positive and negative relays are respectively connected to the output terminals of the first and second constant current source circuits; the output terminals of the positive and negative relays are respectively connected to the input terminals of the first and second constant current source circuits.

[0118] The first current acquisition device is located between the output terminal of the positive relay and the input terminal of the first constant current source circuit, and the second current acquisition device is located between the output terminal of the negative relay and the input terminal of the second constant current source circuit. The first and second current acquisition devices are respectively signal-connected to the central control device, used to acquire the positive current at the positive end of the bus and the negative current at the negative end of the bus, and send the positive and negative currents to the central control device; wherein, the output terminals of the positive and negative relays are respectively connected to the input terminals of the first and second current acquisition devices; the input terminals of the first and second constant current source circuits are respectively connected to the output terminals of the first and second current acquisition devices.

[0119] 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 state of the positive relay and the negative relay based on the comparison result.

[0120] In some embodiments of this example, a relay connected in series between the power supply and the charger is used as an example. The relay status detection device provided in this embodiment is used to detect the relay. The connection circuit diagram of the relay status detection and the relay is shown in Figure 3.

[0121] Specifically, referring to Figure 3, the relay status detection device includes a first constant current source circuit 301, a second constant current source circuit 302, a first current acquisition device 303, and a second current acquisition device 304. The first constant current source circuit 301 is connected to both ends of the 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 the negative relay S2 located at the negative end of the charger's busbar, to provide stable constant current to S1 and S2 respectively. Simultaneously, the first current acquisition device 303 is connected in series between the fixed end of S1 and the input end of the constant current source to acquire the current flowing through the positive end of S1. Similarly, the second current acquisition device 304 is connected in series between the fixed end of S2 and the input end of the constant current source to acquire the current flowing through the negative end of S2.

[0122] Further, referring 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. As shown in Figure 3, in the first constant current source circuit 301, the input terminal of the first switch K1 is connected to the output terminal of the constant current source; the fixed terminal of the positive relay S1 is connected to the input terminal of the constant current source. The movable terminal of the first switch K1 is electrically connected to the input terminal of the first diode D1; the output terminal of the first diode D1 is electrically connected to the movable terminal of the positive relay S1. Similarly, in the second constant current source circuit 302, the input terminal of the second switch K2 is connected to the output terminal of the constant current source; the fixed terminal of the negative relay S2 is connected to the input terminal of the constant current source. The movable terminal of the second switch K2 is electrically connected to the input terminal of the second diode D2; the output terminal of the second diode D2 is electrically connected to the movable terminal of the negative relay S2.

[0123] As shown in Figure 3, after connecting the first constant current source circuit 301 and the second constant current source circuit 302 to the two ends of the positive relay S1 and the two ends of the negative relay S2, respectively, the central control device obtains the status detection results of the positive relay S1 and the negative relay S2 by executing the steps shown in Figure 4. Specifically, the detection steps include:

[0124] Step 401: Close K1, open K2, and obtain the first current A1 collected by the first current acquisition device 303, so as to determine whether to open K1 and close K2 based on A1 and the current output by the constant current source.

[0125] In this embodiment, the main steps are as follows: the central control device controls the first switch K1 to close and the second switch K2 to open, then the first current A1 fed back by the first current acquisition device 303 is acquired, and the state of the switch is determined based on A1 and the current output by the constant current source.

[0126] Specifically, in some embodiments of this example, the constant current source is set to output a fixed current of 1A. When K1 is closed and K2 is open, the state of S1 and S2 can be analyzed to find that the switches S1 and S2 have the following four possible states: S1 is open and S2 is open; S1 is open and S2 is closed; S1 is closed and S2 is open; S1 is closed and S2 is closed.

[0127] When S1 and S2 are both open, there is no return path for the constant current output, and A1 and A2 are both 0. When S1 is open and S2 is closed, the current path is shown by the dashed line in Figure 5, where A1 = 0 and A2 = 1A. When S1 is closed and S2 is open, the current path is shown by the dashed line in Figure 6, where A1 = 1A and A2 = 0. When S1 is closed and S2 is closed, the current path is shown in Figure 7. Here, we assume that the equivalent resistance on path 1 is R1 and the equivalent resistance on path 2 is R2. The equivalent circuit is shown in Figure 8. In practical applications, R1 is the internal resistance of a short section of the copper busbar, and 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 less than R2, so the corresponding current A1 is greater than A2. Therefore, under normal circumstances, the judgment threshold can be set to half of the constant current source output current, which is half of the 1A current, 0.5A, in the example shown in Figure 8. At this time, A1 > 0.5A and A2 < 0.5A. Preferably, this threshold can be adjusted according to the equivalent R1 and R2 values ​​in the actual electrical connection.

[0128] Based on the above analysis of the switching states of S1 and S2 and the corresponding current, in this embodiment, after closing K1 and opening K2, when the value of the first current A1 fed back by the first current acquisition device is less than the threshold of 0.5A, it can be determined that the states of S1 and S2 are only two states: S1 open and S2 open, or S1 open and S2 closed. At this time, there is no need to switch the switching states of K1 and K2.

[0129] When the value of the first current A1 fed back by the first current acquisition device is greater than or equal to the threshold of 0.5A, it can be determined that the states of S1 and S2 are only two states: S1 closed and S2 open, or S1 closed and S2 closed. At this time, it is necessary to switch K1 open and K2 closed.

[0130] Step 402: When it is determined that K1 is not open 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 state of the positive relay S1 and the negative relay S2 according to A2 and the constant current output by the constant current source.

[0131] In this embodiment, the main step is to set a current threshold according to the magnitude 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, i.e., 0.5A, according to the actual electrical conditions.

[0132] The comparison result between the second current A2 and the current threshold is obtained to determine 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 is disconnected and S2 is stuck; when A2 is less than 0.5A, the central control device determines that S1 is disconnected and S2 is disconnected.

[0133] Step 403: When it is determined that K1 is open and K2 is closed, the second current A2 fed back by the second current acquisition device is obtained, so as to obtain the corresponding state of the positive relay S1 and the negative relay S2 according to A2 and the constant current output by the constant current source.

[0134] In this embodiment, the main step is to set a current threshold according to the magnitude 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, i.e., 0.5A, according to the actual electrical conditions.

[0135] The comparison result between the second current A2 and the current threshold is obtained to determine 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 together; and when A2 is less than 0.5A, the central control device determines that S1 is stuck together and S2 is disconnected.

[0136] This embodiment provides a relay status detection device. By placing a low-power constant current source at the positive and negative ends of the high-voltage busbar to provide a constant current to the relay, the status detection of the relay is not affected by the external voltage. Furthermore, by detecting the current in the busbar, the relay status can be quickly and accurately determined under the condition that the internal and external voltages are equal, thus indicating the reliability of the system.

[0137] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit the scope of protection of this application. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application for those skilled in the art.

Claims

1. A state detecting device of a relay, wherein, Includes constant current source circuit, current sensor and main controller; The constant current source circuit is signal-connected to the main controller, which controls the constant current source circuit to apply a constant current to the positive relay connected in series at the positive end of the bus and the negative relay connected in series at the negative end of the bus, respectively; wherein, the input terminals of the positive relay and the negative relay are respectively connected to the output terminal of the constant current source circuit. The output terminals of the positive and negative relays are respectively connected to the input terminal of the constant current source circuit via the current sensor; the current sensor is also signal-connected to the main controller to acquire the positive current at the positive end of the bus and the negative current at the negative end of the bus, and send the positive and negative currents to the main controller; wherein, the output terminals of the positive and negative relays are respectively connected to the input terminal of the current sensor; the input terminal of the constant current source circuit is connected to the output terminal of the current sensor; The main controller is used to receive the positive terminal current and the negative terminal current, and compare the positive terminal current and the negative terminal current with the constant current respectively, so as to determine the state of the positive relay and the negative relay based on the comparison result.

2. The state detection device of a relay according to claim 1, wherein The constant current source circuit includes a constant current source, a first switch, a second switch, a first diode, and a second diode; The input terminals of the first switch and the second switch are electrically connected to the output terminal of the constant current source, respectively; the output terminals of the positive relay and the negative relay are electrically connected to the input terminal of the constant current source through the current sensor. The output terminal of the first switch is electrically connected to the input terminal of the first diode; the output terminal of the second switch is electrically connected to the input terminal of the second diode. The output terminal of the first diode is electrically connected to the input terminal of the positive relay; The output terminal of the second diode is electrically connected to the input terminal of the negative relay.

3. The state detection device of a relay according to claim 2, wherein The main controller is used to control the first switch to close and the second switch to open, so that the constant current source applies the constant current to the positive relay. The main controller is used to receive the positive terminal current of the busbar sent by the current sensor, and to obtain the positive terminal current difference between the positive terminal current and the positive terminal current of the constant current. The main controller is used to control the first switch to open and the second switch to close when it is determined that the positive terminal difference is within a preset tolerance range, so that the constant current source applies the constant current to the negative relay.

4. The state detection device of a relay according to claim 3, wherein The main controller is also used to receive the negative terminal current of the bus negative terminal sent by the current sensor, and to obtain the negative terminal difference between the negative terminal current and the constant current. The main controller is also used to determine that the state of the positive relay is stuck and the state of the negative relay is open when it is determined that the negative terminal difference is not within the tolerance range.

5. The state detection device of a relay according to claim 4, wherein The main controller is also used to determine that the state of the positive relay and the negative relay is sticky when the negative terminal difference is determined to be within the tolerance range.

6. The state detection device of a relay according to claim 3, wherein The main controller is also configured to receive the negative terminal current of the negative terminal of the bus sent by the current sensor and obtain the negative terminal difference between the negative terminal current and the constant current when it is determined that the positive terminal difference is not within the preset tolerance range. The main controller is also used to determine, when the negative terminal difference is within the tolerance range, that the state of the positive relay is open and the state of the negative relay is stuck.

7. The state detection device of a relay according to claim 6, wherein The main controller is also configured to determine that the state of the positive relay and the negative relay is open when it is determined that the negative terminal difference is not within the tolerance range.

8. The state detection device of a relay according to claim 2, wherein The constant current source includes a first constant current source and a second constant current source; The input terminal of the first switch is electrically connected to the output terminal of the first constant current source, and the input terminal of the second switch is electrically connected to the output terminal of the second constant current source; the output terminal of the positive relay is electrically connected to the input terminal of the first constant current source through the current sensor, and the output terminal of the negative relay is electrically connected to the input terminal of the second constant current source through the current sensor.

9. The state detection device of a relay according to claim 8, wherein The current sensor includes a first current sensor and a second current sensor; The output terminal of the positive relay is connected to the input terminal of the first current sensor, and the output terminal of the negative relay is connected to the input terminal of the second current sensor; the input terminal of the first constant current source circuit is connected to the output terminal of the first current sensor, and the input terminal of the second constant current source circuit is connected to the output terminal of the second current sensor.

10. A method of detecting a state of a relay, wherein include: A constant current is applied to the positive relay connected in series at the positive terminal of the busbar and the negative relay connected in series at the negative terminal of the busbar, respectively. Obtain the positive terminal current flowing through the positive relay in the positive terminal of the busbar and the negative terminal current flowing through the negative relay in the negative terminal of the busbar; The positive terminal current, the negative terminal current, and the constant current are compared respectively to determine the state of the positive relay and the negative relay based on the comparison results.

11. The method of claim 10, wherein the step of detecting the state of the relay is performed by a microcomputer. The step of applying constant current to the positive relay connected in series at the positive terminal of the busbar and the negative relay connected in series at the negative terminal of the busbar includes: First, apply the constant current to the positive relay to obtain the positive terminal current flowing through the positive relay in the positive terminal of the bus; Obtain the difference between the positive terminal current and the positive terminal current of the constant current; When the positive terminal difference is within the preset tolerance range, the constant current is applied to the negative terminal relay.

12. The method of claim 11, wherein the step of detecting the state of the relay is performed by a microcomputer. The step of acquiring the comparison results of the positive terminal current, the negative terminal current, and the constant current, respectively, and determining the states of the positive and negative relays based on the comparison results, includes: Obtain the negative terminal current flowing through the negative relay in the negative terminal of the busbar, and obtain the negative terminal difference between the negative terminal current and the negative terminal of the constant current; When the negative terminal difference is not within the tolerance range, the state of the positive relay is determined to be stuck and the state of the negative relay is determined to be open.

13. The method of claim 12, wherein the step of detecting the state of the relay is performed by a microcomputer. After obtaining the difference between the negative terminal current and the negative terminal of the constant current, the method further includes: When the negative terminal difference is within the tolerance range, the state of the positive relay and the negative relay is determined to be sticky.

14. The method of claim 11, wherein the step of detecting the state of the relay is performed by a microcomputer. After obtaining the difference between the positive terminal current and the positive terminal of the constant current, the method further includes: When the positive terminal difference is not within the preset tolerance range, the negative terminal current flowing through the negative relay in the negative terminal of the bus is obtained, and the negative terminal difference between the negative terminal current and the constant current is obtained. When the negative terminal difference is within the tolerance range, the state of the positive relay is determined to be open and the state of the negative relay is determined to be stuck.

15. The method of claim 14, wherein the step of detecting the state of the relay is performed by a microprocessor. After obtaining the difference between the negative terminal current and the negative terminal of the constant current, the method further includes: When the negative terminal difference is not within the tolerance range, the state of the positive relay and the negative relay is determined to be open.

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