Relay state detection device and vehicle

Abstract

The invention discloses a relay state detection device and a vehicle. The relay state detection device comprises a biasing circuit, a voltage division circuit, an impedance matching circuit, an operational amplifier, a power supply and a control module, a first end of the biasing circuit is connected with an anode of a power supply, a second end of the biasing circuit is connected with a first end of the voltage division circuit and an in-phase input end of the operational amplifier, a second end of the voltage division circuit is connected with a first contact of the relay, and a first end of the impedance matching circuit is connected with a second contact of the relay and an inverted input end of the operational amplifier. The second end of the impedance matching circuit is connected with the cathode of the power supply; the output end of the operational amplifier is connected with the first input end of the control module; and the control module is used for determining the resistance value of a contact resistor between the first contact of the relay and the second contact of the relay according to the signal of the first input end of the control module, and determining the state of the relay according to the resistance value of the contact resistor and the detected relay driving signal. The accuracy of relay state detection can be improved.

Description

Technical Field

[0001] This application relates to the technical field of electronic circuits, and particularly relates to a relay state detection device and a vehicle. Background Art

[0002] With the development of electric vehicles, using high-voltage and high-current relays on vehicles is the current mainstream low-cost solution. However, current surges are likely to cause the contact points of the relay to stick. To address the problem of the contact points of the relay sticking, generally, the voltage difference across the relay is detected for judgment, which is prone to detection errors and false fault reports. Summary of the Invention

[0003] An embodiment of this application provides a relay state detection device and a vehicle, which can improve the accuracy of relay state detection.

[0004] In a first aspect of an embodiment of this application, a relay state detection device is provided, including a bias circuit, a voltage division circuit, an impedance matching circuit, an operational amplifier, a power supply, and a control module; a first end of the bias circuit is connected to the positive pole of the power supply, a second end of the bias circuit is connected to a first end of the voltage division circuit and the non-inverting input terminal of the operational amplifier, a second end of the voltage division circuit is connected to a first contact of the relay, a first end of the impedance matching circuit is connected to a second contact of the relay and the inverting input terminal of the operational amplifier, a second end of the impedance matching circuit is connected to the negative pole of the power supply, and an output terminal of the operational amplifier is connected to a first input terminal of the control module;

[0005] The control module is configured to determine the resistance value of the contact resistance between the first contact of the relay and the second contact of the relay according to the signal at the first input terminal of the control module, and is configured to determine the state of the relay according to the resistance value of the contact resistance and the detected relay drive signal.

[0006] In an embodiment of this application, the bias circuit, the voltage division circuit, the impedance matching circuit, the operational amplifier, the power supply, and the control module are not in the same circuit as the relay drive circuit and the main circuit. The power supply is not the drive power supply of the relay. By using an independent power supply to measure the contact resistance, the measured resistance value of the contact resistance will not be interfered by the loads (the load of the first contact and the load of the second contact) of the main circuit of the relay, thereby improving the accuracy of relay state detection.

[0007] Optionally, the bias circuit includes a first resistor, a first end of the first resistor is connected to the positive pole of the power supply, and a second end of the first resistor is connected to a first end of the voltage division circuit and the non-inverting input terminal of the operational amplifier.

[0008] Optionally, the voltage dividing circuit includes a first electronic switch, a second resistor, and a diode. The first input terminal of the first electronic switch is connected to the non-inverting input terminal of the operational amplifier. The first output terminal of the first electronic switch is connected to the first end of the second resistor. The second end of the second resistor is connected to the positive electrode of the diode. The negative electrode of the diode is connected to the first contact of the relay. The first output terminal of the control module is connected to the second input terminal of the first electronic switch. The second output terminal of the first electronic switch is grounded.

[0009] In the embodiment of the present application, the diode can prevent the current in the main circuit of the relay from flowing back into the relay state detection device, thereby protecting the relay state detection device and improving the accuracy of the relay state detection.

[0010] Optionally, the impedance matching circuit includes a third resistor. The first end of the third resistor is connected to the second contact of the relay. The second end of the third resistor is connected to the negative electrode of the power supply.

[0011] Optionally, the impedance matching circuit includes a fourth resistor, a fifth resistor, and a second electronic switch. The first end of the fourth resistor is connected to the second contact of the relay. The second end of the fourth resistor is connected to the first end of the fifth resistor and the first input terminal of the second electronic switch. The second end of the fifth resistor is connected to the first output terminal of the second electronic switch and the negative electrode of the power supply. The second output terminal of the control module is connected to the second input terminal of the second electronic switch. The second output terminal of the second electronic switch is grounded.

[0012] In the embodiment of the present application, the control module can control the connection or disconnection between the first input terminal and the first output terminal of the second electronic switch, thereby adjusting the resistance value of the impedance matching circuit. Through redundant detection, the resistance value of the relay contact resistance is calibrated, thereby improving the accuracy of the relay state detection.

[0013] Optionally, the second input terminal of the control module is connected to the output terminal of the driving detection circuit of the relay.

[0014] Optionally, the control module is configured to determine the resistance value of the contact resistance between the first contact and the second contact of the relay according to the signal at the first input terminal of the control module, including:

[0015] The control module is configured to determine the resistance value of the contact resistance between the first contact and the second contact of the relay according to the signal at the first input terminal of the control module when no relay closing command is received, or when a relay closing command is received, or when a relay opening command is received.

[0016] Optionally, the control module is configured to determine the resistance value of the contact resistance between the first contact and the second contact of the relay according to the signal at the first input end of the control module, including:

[0017] The control module is configured to, when the relay is in a closed state and the first input end and the first output end of the second electronic switch are connected, determine a first resistance value of the contact resistance between the first contact and the second contact of the relay according to the signal at the first input end of the control module; and is configured to, when the relay is in a closed state and the first input end and the first output end of the second electronic switch are disconnected, determine a second resistance value of the contact resistance between the first contact and the second contact of the relay according to the signal at the first input end of the control module; and is configured to calibrate according to the first resistance value and the second resistance value and determine the resistance value of the contact resistance;

[0018] The control module is further configured to determine that the relay has a fault when it is determined according to the resistance value of the contact resistance that the state of the relay is an adhesion state or an open state.

[0019] Optionally, the control module is configured to determine the state of the relay according to the resistance value of the contact resistance, including:

[0020] The control module is configured to determine that the relay is in a closed state when the resistance value of the contact resistance is less than a first threshold; and is configured to determine that the relay is in an adhesion state when the resistance value of the contact resistance is greater than or equal to the first threshold and less than a second threshold; and is configured to determine that the relay is in an open state when the resistance value of the contact resistance is greater than a third threshold; the first threshold is less than the second threshold, and the second threshold is less than the third threshold.

[0021] A second aspect of the embodiments of the present application provides a vehicle, including the relay state detection device and the relay according to any one of the first aspects of the embodiments of the present application.

[0022] The relay state detection device of the embodiments of the present application measures the contact resistance through an independent power supply, so that the measured resistance value of the contact resistance will not be interfered by the load of the main circuit of the relay, thereby improving the accuracy of relay state detection. Description of the Drawings

[0023] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0024] Figure 1 is a schematic structural diagram of a relay state detection device provided by an embodiment of the present application;

[0025] Figure 2 is a schematic structural diagram of another relay state detection device provided by an embodiment of the present application;

[0026] Figure 3 is a schematic structural diagram of yet another relay state detection device provided by an embodiment of the present application;

[0027] Figure 4 is a schematic structural diagram of a vehicle provided by an embodiment of the present application. Detailed implementation manners

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0029] The terms "first", "second", etc. in the specification and claims of the present application and the above accompanying drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally further include steps or units not listed, or may optionally further include other steps or units inherent to these processes, products or devices.

[0030] Referring to "embodiment" in the present application means that the specific features, structures or characteristics described in connection with the embodiment may be included in at least one embodiment of the present application. The phrase appears in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described in the present application can be combined with other embodiments.

[0031] Please refer to Figure 1 , Figure 1It is a schematic structural diagram of a relay state detection device provided by an embodiment of the present application. As Figure 1 shown, the relay state detection device 100 includes a bias circuit 10, a voltage dividing circuit 20, an impedance matching circuit 30, an operational amplifier 40, a power supply 50, and a control module 60; the first end of the bias circuit is connected to the positive pole of the power supply 50, the second end of the bias circuit 10 is connected to the first end of the voltage dividing circuit 20 and the non-inverting input terminal of the operational amplifier 40, the second end of the voltage dividing circuit 20 is connected to the first contact of the relay (such as Figure 1 the contact C shown), the first end of the impedance matching circuit 30 is connected to the second contact of the relay (such as Figure 1 the contact D shown) and the inverting input terminal of the operational amplifier 40, the second end of the impedance matching circuit 30 is connected to the negative pole of the power supply 50, and the output terminal of the operational amplifier 40 is connected to the first input terminal of the control module 60;

[0032] The control module 60 is configured to determine the resistance value of the contact resistance between the first contact of the relay and the second contact of the relay according to the signal at the first input terminal of the control module 60, and is configured to determine the state of the relay according to the resistance value of the contact resistance.

[0033] In the embodiment of the present application, the bias circuit 10 may include a bias resistor, or may include a bias resistor and a temperature compensation circuit. Among them, the temperature compensation circuit may include a thermistor, and the thermistor and the bias resistor may be connected in series or in parallel. When the temperature changes, the resistance value of the thermistor is adjusted to compensate for the change of the bias resistor, so as to achieve the effect of temperature compensation, and the overall resistance value of the bias circuit 10 remains stable with the change of temperature.

[0034] The voltage dividing circuit 20 may be connected in series between the positive and negative poles of the power supply 50 together with the bias circuit 10 and the impedance matching circuit 30, and the resistance value of the contact resistance can be measured by measuring the voltage value divided by the voltage dividing circuit 20.

[0035] The impedance of the impedance matching circuit 30 is adjustable. For example, when the resistance value of the contact resistance is high, the resistance value of the impedance matching circuit 30 is increased, and when the resistance value of the contact resistance is low, the resistance value of the impedance matching circuit 30 is decreased, so as to improve the accuracy of measuring the resistance value of the contact resistance.

[0036] The operational amplifier 40 can amplify the difference between the voltage at the non-inverting input terminal and the voltage at the inverting input terminal by a certain multiple and output it to the first input terminal of the control module 60.

[0037] The power supply 50 can be an independently set power supply, which is different from the power supply of the driving circuit of the relay and also different from the power supply of the main circuit of the relay. The voltage provided by the power supply 50 can be any value between 3.3V and 18V. Exemplarily, the power supply 50 can be a 12V power supply.

[0038] The control module 60 can be a microcontroller unit (MCU) or a digital signal processor (DSP).

[0039] Among them, the main circuit of the relay includes: an input load, a first contact (such as Figure 1 the contact C shown), a second contact (such as Figure 1 the contact D shown), an output load, and the power supply of the main circuit of the relay ( Figure 1 not shown).

[0040] Among them, the driving circuit of the relay includes: a driving signal +, the first end of the relay coil (such as Figure 1 the A shown), the second end of the relay coil (such as Figure 1 the B shown), a driving signal -, and the power supply of the driving circuit of the relay ( Figure 1 not shown).

[0041] The control principle of the relay is as follows: The power supply of the driving circuit controls the magnitudes of the driving signal + and the driving signal -, thereby controlling the current of the relay coil. When the current of the relay coil is greater than a certain threshold, the first contact and the second contact of the relay are connected, thereby achieving the closing of the relay; when the current of the relay coil is less than a certain threshold, the first contact and the second contact of the relay are disconnected, thereby achieving the opening of the relay.

[0042] In the embodiments of the present application, the bias circuit 10, the voltage dividing circuit 20, the impedance matching circuit 30, the operational amplifier 40, the power supply, and the control module 60 are not in the same circuit as the driving circuit and the main circuit of the relay. The power supply is not the driving power supply of the relay. By using an independent power supply to measure the contact resistance, the measured value of the contact resistance will not be interfered by the load of the main circuit of the relay, thereby improving the accuracy of the relay state detection.

[0043] Optionally, as Figure 1As shown, the second input terminal of the control module 60 is connected to the output terminal of the driving detection circuit of the relay. The first input terminal of the driving detection circuit is connected to the first end of the relay coil, and the second input terminal of the driving detection circuit is connected to the second end of the relay coil, so as to detect the magnitudes of the driving signal + and the driving signal -, and then determine whether the relay is in the driving state according to the magnitudes of the driving signal + and the driving signal -. The second input terminal of the control module 60 is connected to the output terminal of the driving detection circuit, so as to know whether the relay is in the driving state.

[0044] Please refer to Figure 2 , Figure 2 which is a schematic structural diagram of another relay state detection device provided by an embodiment of the present application. Figure 2 which is obtained on the basis of Figure 1 , as Figure 2 shown, on the basis of Figure 1 , the bias circuit 10 includes a first resistor R1. The first end of the first resistor R1 is connected to the positive pole of the power supply, and the second end of the first resistor R1 is connected to the first end of the voltage dividing circuit 20 and the non-inverting input terminal of the operational amplifier 40.

[0045] Optionally, as Figure 2 shown, the voltage dividing circuit 20 includes a first electronic switch (such as the electronic switch 1 shown in Figure 2 ), a second resistor R2, and a diode D1. The first input terminal of the first electronic switch is connected to the non-inverting input terminal of the operational amplifier 40. The first output terminal of the first electronic switch is connected to the first end of the second resistor R2. The second end of the second resistor R2 is connected to the positive pole of the diode D1. The negative pole of the diode D1 is connected to the first contact of the relay. The first output terminal of the control module 60 is connected to the second input terminal of the first electronic switch, and the second output terminal of the first electronic switch is grounded.

[0046] In the embodiment of the present application, the diode D1 can prevent the current in the main circuit of the relay from flowing back into the relay state detection device, thereby protecting the relay state detection device and improving the detection accuracy of the relay state detection device.

[0047] Optionally, as Figure 2 shown, the impedance matching circuit 30 includes a third resistor R3. The first end of the third resistor R3 is connected to the second contact of the relay, and the second end of the third resistor R3 is connected to the negative pole of the power supply.

[0048] In the embodiment of the present application, the resistance value of the impedance matching circuit 30 is a fixed resistance value.

[0049] Based on Figure 2The relay state detection device shown, the control module 60 can determine the resistance value of the contact resistance according to the following formula:

[0050] R cd = U R *(R1 + R3) / (U0 - U R ) - U D1 - R2;

[0051] Wherein, R cd is the resistance value of the contact resistance between the first contact of the relay and the second contact of the relay, U0 is the voltage across the positive and negative terminals of the power supply 50 (for example, U0 = 12V), U R is the voltage difference based on the voltages at the non-inverting input terminal and the inverting input terminal of the operational amplifier 40, R1 is the resistance value of the first resistor R1, R2 is the resistance value of the second resistor R2, R3 is the resistance value of the third resistor R3, U D1 is the conduction voltage drop of the diode D1.

[0052] Wherein, the control module 60 can calculate U R through the signal at the output terminal of the operational amplifier 40. Exemplarily, if the amplification factor of the operational amplifier 40 is A and the output signal is U out , then U R = U out / A.

[0053] Please refer to Figure 3 , Figure 3 which is a schematic structural diagram of another relay state detection device provided by an embodiment of the present application. As Figure 3 shown, the impedance matching circuit 30 includes a fourth resistor R4, a fifth resistor R5 and a second electronic switch (such as Figure 3 the electronic switch 2 shown), the first end of the fourth resistor R4 is connected to the second contact of the relay, the second end of the fourth resistor R4 is connected to the first end of the fifth resistor R5 and the first input terminal of the second electronic switch, the second end of the fifth resistor R5 is connected to the first output terminal of the second electronic switch and the negative pole of the power supply; the second output terminal of the control module 60 is connected to the second input terminal of the second electronic switch, and the second output terminal of the second electronic switch is grounded.

[0054] In an embodiment of the present application, the control module 60 can control the connection or disconnection between the first input terminal and the first output terminal of the second electronic switch, so as to adjust the resistance value of the impedance matching circuit 30, and calibrate the resistance value of the relay contact resistance through redundant detection, thereby improving the accuracy of relay state detection.

[0055] When the first input terminal and the first output terminal of the second electronic switch are connected, based onFigure 3 For the relay state detection device shown, the control module 60 can determine the resistance value of the contact resistance according to the following formula:

[0056] R cd = U R *(R1 + R4) / (U0 - U R ) - U D1 - R2;

[0057] Wherein, R cd is the resistance value of the contact resistance between the first contact of the relay and the second contact of the relay, U0 is the voltage across the positive and negative terminals of the power supply 50 (for example, U0 = 12V), U R is the voltage difference based on the voltage of the non-inverting input terminal and the inverting input terminal of the operational amplifier 40, R1 is the resistance value of the first resistor R1, R2 is the resistance value of the second resistor R2, R4 is the resistance value of the fourth resistor R4, and U D1 is the conduction voltage drop of the diode D1.

[0058] When the first input terminal of the second electronic switch and the first output terminal of the second electronic switch are disconnected, based on the Figure 3 relay state detection device shown, the control module 60 can determine the resistance value of the contact resistance according to the following formula:

[0059] R cd = U R *(R1 + R4 + R5) / (U0 - U R ) - U D1 - R2;

[0060] Wherein, R cd is the resistance value of the contact resistance between the first contact of the relay and the second contact of the relay, U0 is the voltage across the positive and negative terminals of the power supply 50 (for example, U0 = 12V), U R is the voltage difference based on the voltage of the non-inverting input terminal and the inverting input terminal of the operational amplifier 40, R1 is the resistance value of the first resistor R1, R2 is the resistance value of the second resistor R2, R4 is the resistance value of the fourth resistor R4, R5 is the resistance value of the fifth resistor R5, and U D1 is the conduction voltage drop of the diode D1.

[0061] Among them, Figure 3 the resistance value of the impedance matching circuit 30 is adjustable, Figure 2 the resistance value of the impedance matching circuit 30 is a fixed value.

[0062] Optionally, the control module 60 is configured to determine the resistance value of the contact resistance between the first contact of the relay and the second contact of the relay according to the signal at the first input terminal of the control module 60, including:

[0063] The control module 60 is configured to determine the resistance value of the contact resistance between the first contact and the second contact of the relay according to the signal at the first input end of the control module 60 when no relay closing command is received, or when a relay closing command is received, or when a relay opening command is received.

[0064] The embodiment of the present application can execute a static detection strategy for the relay state, and detect the state of the relay in three different situations: when no relay closing command is received, when a relay closing command is received, and when a relay opening command is received.

[0065] The second input end of the control module 60 is connected to the output end of the driving detection circuit. The control module 60 can determine whether the relay has received a closing command and whether it has received an opening command according to the signal output from the output end of the driving detection circuit, so as to know whether the relay is in a driving state.

[0066] When no relay closing command is received, the following relay state detection process can be executed: after the contacts of the relay reach a stable state, the power supply 50 starts to be applied. When it is detected that the relay is in an undriven state and the first electronic switch is in an undriven and unclosed state, the first electronic switch is closed (the first output end of the control module 60 outputs a closing signal to connect the first input end and the first output end of the first electronic switch). The sampling voltage is input to the in-phase input end and the anti-phase input end of the operational amplifier 40 respectively. The control module 60 calculates the contact resistance of the relay according to the signal at the output end of the operational amplifier 40, and the control module 60 determines whether the relay is in an open state or an adhesive state according to the contact resistance of the relay.

[0067] When a relay closing command is received, the following relay state detection process can be executed: after the contacts of the relay reach a stable closed state, the power supply 50 starts to be applied. When it is detected that the relay is in a driving state and the first electronic switch is in an undriven and unclosed state, the first electronic switch is closed (the first output end of the control module 60 outputs a closing signal to connect the first input end and the first output end of the first electronic switch). The sampling voltage is input to the in-phase input end and the anti-phase input end of the operational amplifier 40 respectively. The control module 60 calculates the contact resistance of the relay according to the signal at the output end of the operational amplifier 40, and the control module 60 determines whether the relay is in an open state, a closed state or an adhesive state according to the contact resistance of the relay.

[0068] In the embodiment of the present application, during the closing process of the relay, if the closing time is long, large current and arcing may occur, resulting in the adhesion of the relay. The embodiment of the present application can detect the adhesion fault of the relay closing.

[0069] In the case of receiving a relay closing / opening command, the following relay state detection process can be executed: After the relay contacts reach a stable open state, power supply 50 starts to be applied. When it is detected that the relay is in an undriven state and the first electronic switch is in an undriven and unclosed state, the first electronic switch is closed (the first output terminal of the control module 60 outputs a closing signal to connect the first input terminal and the first output terminal of the first electronic switch). The sampling voltage is input to the non-inverting input terminal and the inverting input terminal of the operational amplifier 40 respectively. The control module 60 calculates the contact resistance of the relay based on the signal at the output terminal of the operational amplifier 40, and the control module 60 determines whether the relay is in an open state or an adhesive state based on the contact resistance of the relay.

[0070] In the embodiment of the present application, during the disconnection process of the relay, when the relay is in a loaded state, if the voltage difference across the relay is large, arcing may occur, resulting in the adhesion of the relay. The embodiment of the present application can detect the adhesion fault of the relay disconnection.

[0071] Optionally, after executing the relay state static detection strategy, if the relay is fault-free, the relay is closed, input load and output load are respectively added to the input side and the output side of the relay, and dynamic contact resistance detection is performed in real time when the relay is in the closed state. If the measured resistance value is abnormal at least once within N detection cycles, the control module 60 reports the fault information of the relay fault (for example, the fault information of the relay adhesion or disconnection). N can be set as an integer greater than or equal to 2, and the detection cycle can be set to any value within 10 to 1000 milliseconds (ms). Exemplarily, the detection cycle can be set to 50 ms. If the resistance value is abnormal 3 times within 200 ms, the fault information of the relay adhesion or disconnection can be reported.

[0072] Optionally, the control module 60 is configured to determine the resistance value of the contact resistance between the first contact and the second contact of the relay according to the signal at the first input terminal of the control module 60, including:

[0073] The control module 60 is configured to determine a first resistance value of the contact resistance between the first contact and the second contact of the relay according to the signal at the first input end of the control module 60 when the relay is in a closed state and the first input end and the first output end of the second electronic switch are connected; and is configured to determine a second resistance value of the contact resistance between the first contact and the second contact of the relay according to the signal at the first input end of the control module 60 when the relay is in a closed state and the first input end and the first output end of the second electronic switch are disconnected; and is configured to perform calibration based on the first resistance value and the second resistance value and determine the resistance value of the contact resistance.

[0074] The control module 60 is further configured to determine that the relay is faulty when it is determined that the state of the relay is an adhesion state or a disconnection state based on the resistance value of the contact resistance.

[0075] In the embodiment of the present application, by changing the resistance value of the impedance matching circuit 30, two resistance values can be calculated: a first resistance value and a second resistance value. Determining the resistance value of the contact resistance based on the first resistance value and the second resistance value can improve the detection accuracy of the contact resistance between the first contact and the second contact of the relay. For example, the average value of the first resistance value and the second resistance value can be used as the resistance value of the contact resistance, or the resistance value of the contact resistance can be calculated by performing weighted summation based on the first resistance value and the second resistance value.

[0076] The control module 60 performs calibration based on the first resistance value and the second resistance value and determines the resistance value of the contact resistance. Specifically, it can be:

[0077] When the difference between the first resistance value and the second resistance value is less than a set threshold, the average value of the first resistance value and the second resistance value is used as the resistance value of the contact resistance.

[0078] When the difference between the first resistance value and the second resistance value is greater than the set threshold, then it is determined that the first resistance value or the second resistance value is the resistance value of the contact resistance.

[0079] In the embodiment of the present application, when the difference between the first resistance value and the second resistance value is small, it indicates that the errors of both resistance values from the true resistance value are small, and the reliability of both resistance values is very high. The average value of the two can be used as the resistance value of the contact resistance, thereby improving the detection accuracy of the contact resistance.

[0080] When the difference between the first resistance value and the second resistance value is greater than the set threshold, it indicates that the error of one of the two resistance values from the true resistance value is large. Then, the resistance value with the smaller error can be determined as the resistance value of the contact resistance. Exemplarily, taking Figure 3 as an example, it can be determined that (R1 + R4) / (UD1 (R1 + R4 + R5) / (U + R2) and (R1 + R4) / (U + R2), whichever is closer to 0.5. If (R1 + R4) / (U + R2) is closer to 0.5, then determine that the first resistance value is the resistance value of the contact resistance; if (R1 + R4 + R5) / (U + R2) is closer to 0.5, then determine that the second resistance value is the resistance value of the contact resistance. Wherein, R1 is the resistance value of the first resistor R1, R2 is the resistance value of the second resistor R2, R4 is the resistance value of the fourth resistor R4, R5 is the resistance value of the fifth resistor R5, and U D1 (R1 + R4) / (U + R2) and (R1 + R4 + R5) / (U + R2), whichever is closer to 0.5. If (R1 + R4) / (U + R2) is closer to 0.5, then determine that the first resistance value is the resistance value of the contact resistance; if (R1 + R4 + R5) / (U + R2) is closer to 0.5, then determine that the second resistance value is the resistance value of the contact resistance. Wherein, R1 is the resistance value of the first resistor R1, R2 is the resistance value of the second resistor R2, R4 is the resistance value of the fourth resistor R4, R5 is the resistance value of the fifth resistor R5, and U D1 (R1 + R4) / (U + R2) and (R1 + R4 + R5) / (U + R2), whichever is closer to 0.5. If (R1 + R4) / (U + R2) is closer to 0.5, then determine that the first resistance value is the resistance value of the contact resistance; if (R1 + R4 + R5) / (U + R2) is closer to 0.5, then determine that the second resistance value is the resistance value of the contact resistance. Wherein, R1 is the resistance value of the first resistor R1, R2 is the resistance value of the second resistor R2, R4 is the resistance value of the fourth resistor R4, R5 is the resistance value of the fifth resistor R5, and U D1 (R1 + R4) / (U + R2) and (R1 + R4 + R5) / (U + R2), whichever is closer to 0.5. If (R1 + R4) / (U + R2) is closer to 0.5, then determine that the first resistance value is the resistance value of the contact resistance; if (R1 + R4 + R5) / (U + R2) is closer to 0.5, then determine that the second resistance value is the resistance value of the contact resistance. Wherein, R1 is the resistance value of the first resistor R1, R2 is the resistance value of the second resistor R2, R4 is the resistance value of the fourth resistor R4, R5 is the resistance value of the fifth resistor R5, and U D1 is the forward voltage drop of the diode D1.

[0081] Optionally, the control module 60 is configured to determine the state of the relay according to the resistance value of the contact resistance, including:

[0082] The control module 60 is configured to determine that the relay is in a closed state when the resistance value of the contact resistance is less than a first threshold; and is configured to determine that the relay is in a stuck state when the resistance value of the contact resistance is greater than or equal to the first threshold and less than a second threshold; and is configured to determine that the relay is in an open state when the resistance value of the contact resistance is greater than a third threshold; the first threshold is less than the second threshold, and the second threshold is less than the third threshold.

[0083] In the embodiment of the present application, the first threshold, the second threshold, and the third threshold are set in advance and stored in the memory (such as, a non-volatile memory) of the control module 60.

[0084] Exemplarily, the first threshold can be set to 0.4 milliohms (mΩ), the second threshold can be set to 1 mΩ, and the third threshold can be set to 2 mΩ. When the contact resistance < 0.4 mΩ, the relay is in a closed state; when the contact resistance ≥ 0.4 mΩ and < 1 mΩ, the relay is in a stuck state; when the contact resistance ≥ 2 mΩ, the relay is in an open state.

[0085] It should be noted that the above example is a possible example, and the first threshold, the second threshold, and the third threshold can be set to other values in advance according to the model of the relay, which is not limited in the embodiment of the present application.

[0086] Please refer to Figure 4 , Figure 4 which is a schematic structural diagram of a vehicle provided by the embodiment of the present application. As Figure 4 shown, the vehicle may include a relay state detection device 100 and a relay 200. Among them, the relay 200 may be a relay on the vehicle. The vehicle may be an electric vehicle or a hybrid vehicle.

[0087] Figure 4 For the specific structure and working principle of the relay state detection device 100 in [reference], please refer to the above embodiments, which will not be elaborated here.

[0088] In the above embodiments, the descriptions of the respective embodiments have their own focuses. For parts not detailed in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0089] In several embodiments provided in the present application, it should be understood that the disclosed relay state detection device and vehicle can be implemented in other ways. For example, the relay state detection device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

Claims

1. A relay state detection device, characterized in that, It includes a bias circuit, a voltage dividing circuit, an impedance matching circuit, an operational amplifier, a power supply, and a control module; the first end of the bias circuit is connected to the positive pole of the power supply, the second end of the bias circuit is connected to the first end of the voltage dividing circuit and the non-inverting input terminal of the operational amplifier, the second end of the voltage dividing circuit is connected to the first contact of the relay, the first end of the impedance matching circuit is connected to the second contact of the relay and the inverting input terminal of the operational amplifier, the second end of the impedance matching circuit is connected to the negative pole of the power supply, and the output terminal of the operational amplifier is connected to the first input terminal of the control module; The control module is configured to determine the resistance value of the contact resistance between the first contact and the second contact of the relay according to the signal at the first input terminal of the control module, and to determine the state of the relay according to the resistance value of the contact resistance and the detected relay drive signal.

2. The relay state detection device according to claim 1, wherein, The bias circuit includes a first resistor, the first end of the first resistor is connected to the positive pole of the power supply, and the second end of the first resistor is connected to the first end of the voltage dividing circuit and the non-inverting input terminal of the operational amplifier.

3. The relay state detection device according to claim 1, characterized in that The voltage dividing circuit includes a first electronic switch, a second resistor, and a diode. The first input terminal of the first electronic switch is connected to the non-inverting input terminal of the operational amplifier, the first output terminal of the first electronic switch is connected to the first end of the second resistor, the second end of the second resistor is connected to the positive pole of the diode, and the negative pole of the diode is connected to the first contact of the relay; the first output terminal of the control module is connected to the second input terminal of the first electronic switch, and the second output terminal of the first electronic switch is grounded.

4. The relay state detection device according to claim 1, characterized in that, The impedance matching circuit includes a third resistor, the first end of the third resistor is connected to the second contact of the relay, and the second end of the third resistor is connected to the negative pole of the power supply.

5. The relay state detection device according to claim 1, characterized in that The impedance matching circuit includes a fourth resistor, a fifth resistor, and a second electronic switch. The first end of the fourth resistor is connected to the second contact of the relay, the second end of the fourth resistor is connected to the first end of the fifth resistor and the first input terminal of the second electronic switch, and the second end of the fifth resistor is connected to the first output terminal of the second electronic switch and the negative pole of the power supply; The second output terminal of the control module is connected to the second input terminal of the second electronic switch, and the second output terminal of the second electronic switch is grounded.

6. The relay state detection device according to claim 1, characterized in that The second input terminal of the control module is connected to the output terminal of the relay drive detection circuit.

7. The relay state detection device according to any one of claims 1 to 6, characterized in that, The control module, for determining the resistance value of the contact resistance between the first contact and the second contact of the relay according to the signal at the first input terminal of the control module, includes: The control module, for determining the resistance value of the contact resistance between the first contact and the second contact of the relay according to the signal at the first input terminal of the control module when no relay closing command is received or when a relay closing command or a relay opening command is received.

8. The relay state detection device according to claim 5, characterized in that The control module is configured to determine the resistance value of the contact resistance between the first contact of the relay and the second contact of the relay according to the signal at the first input end of the control module, and includes: The control module is configured to, when the relay is in a closed state and the first input end and the first output end of the second electronic switch are connected, determine a first resistance value of the contact resistance between the first contact of the relay and the second contact of the relay according to the signal at the first input end of the control module; and is configured to, when the relay is in a closed state and the first input end and the first output end of the second electronic switch are disconnected, determine a second resistance value of the contact resistance between the first contact of the relay and the second contact of the relay according to the signal at the first input end of the control module; and is configured to calibrate according to the first resistance value and the second resistance value and determine the resistance value of the contact resistance; The control module is further configured to determine that the relay fails when it is determined according to the resistance value of the contact resistance that the state of the relay is an adhesion state or an open state.

9. The relay state detection device according to any one of claims 1 to 6 and 8, characterized in that The control module is configured to determine the state of the relay according to the resistance value of the contact resistance, and includes: The control module is configured to determine that the relay is in a closed state when the resistance value of the contact resistance is less than a first threshold; and is configured to determine that the relay is in an adhesion state when the resistance value of the contact resistance is greater than or equal to the first threshold and less than a second threshold; and is configured to determine that the relay is in an open state when the resistance value of the contact resistance is greater than a third threshold; the first threshold is less than the second threshold, and the second threshold is less than the third threshold.

10. A vehicle, characterized in that, Comprising the relay state detection device and the relay according to any one of claims 1 to 9.

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