Relay adhesion detection circuit, relay adhesion detection method and vehicle

Abstract

The invention provides a relay adhesion detection circuit, a relay adhesion detection method and a vehicle. The circuit comprises a controller, two comparator modules and a voltage division circuit, the voltage division circuit is connected to positive and negative buses at the two ends of the two relays so as to divide the voltage at the two ends of the relays, and the two comparator modules are connected to the voltage division circuit and the controller respectively; the first input ends of the two comparator modules receive divided voltages at the two ends of the relay respectively, the second input ends of the two comparator modules receive reference signals sent by the controller respectively, and the output ends of the two comparator modules output comparison signals to the controller; the controller is configured to generate a reference signal, send the reference signal to the comparator module, receive a comparison signal output by the comparator module and judge the adhesion state of the relay based on the duty ratio of the comparison signal. The problems that the cost is too high due to the adoption of an isolation operational amplifier, and the judgment standard of adhesion detection needs to be adjusted according to the bus voltage change are solved.

Description

Technical Field

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

[0002] During the vehicle charging process, adhesion of the relay in the DC fast charger will cause high voltage at the charging port, bringing the risk of electric shock; at the same time, if the DC interface is reused for AC charging, the adhesion of the DC fast charger relay will cause the risk of AC power directly connecting to the high-voltage battery pack, affecting the normal function of the high-voltage DC battery pack, and even damaging the battery pack. At present, whether the relay is adhered is judged by detecting the voltage at both ends of the DC fast charger relay. However, with the increasing integration of vehicle power systems, especially control circuits, the voltage detection at both ends of the DC fast charger relay requires isolation detection. Due to the price of isolation op amps, this solution based on isolation op amps to collect the voltage at both ends of the relay is relatively expensive. In addition, the judgment criteria for adhesion detection under different bus voltage conditions also need to be adjusted accordingly according to the bus voltage. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a relay adhesion detection circuit, a relay adhesion detection method and a vehicle, so as to solve the problem that the use of isolation operational amplifiers leads to excessively high costs, and the judgment criteria of adhesion detection need to be adjusted according to the change of bus voltage.

[0004] In order to solve or improve the above technical problems to a certain extent, according to one aspect of the present invention, a relay adhesion detection circuit is provided, wherein the relay is respectively connected to the positive and negative bus bars between the DC charging port and the battery pack of the vehicle, and the relay adhesion detection circuit comprises: a controller, two comparator modules and a voltage divider circuit;

[0005] Wherein, the voltage divider circuit is connected to the positive and negative busbars at both ends of the two relays to divide the voltage at both ends of the relays, and the two comparator modules are respectively connected to the voltage divider circuit and the controller;

[0006] Wherein, the first input ends of the two comparator modules respectively receive the divided voltages at both ends of the relay, the second input ends of the two comparator modules respectively receive the reference signals sent by the controller, and the output ends of the two comparator modules output comparison signals to the controller;

[0007] The controller is configured to generate the reference signal and send it to the comparator module, receive the comparison signal output by the comparator module, and determine the sticking state of the relay based on the duty cycle of the comparison signal.

[0008] In some embodiments, the relay adhesion detection circuit also includes two digital isolator modules, which are respectively connected to the two comparator modules, and the two digital isolator modules are both connected to the controller, so that the reference signal is transmitted to the comparator module after passing through the digital isolator module, and the comparison signal is transmitted to the controller through the digital isolator module.

[0009] In some embodiments, the relay adhesion detection circuit further includes two triangular wave generating modules, which are respectively connected to the second input terminals of the two comparator modules, and the two triangular wave generating modules are respectively connected to the two digital isolator modules;

[0010] The reference signal generated by the controller is a square wave signal having a preset duty cycle and a preset frequency;

[0011] After the triangular wave generating module converts the square wave signal into a triangular wave signal, the triangular wave signal is sent to the comparator module.

[0012] In some implementations, the triangle wave generating module includes: an operational amplifier, a ninth resistor, a tenth resistor, and a capacitor filter;

[0013] The ninth resistor is connected to the first input terminal of the operational amplifier, the tenth resistor is connected to the second input terminal of the operational amplifier, and the capacitor filter is respectively connected to the second input terminal of the operational amplifier and the output terminal of the operational amplifier.

[0014] In some implementations, a duty cycle of the comparison signal output by the comparator module does not vary with the voltage of the battery pack.

[0015] In some embodiments, the controller is configured to compare the duty cycle of the comparison signal with a pre-stored correspondence between the duty cycle and the sticking state of the relay after receiving the comparison signal, and determine the sticking state of the relay according to the comparison result.

[0016] In some embodiments, the voltage divider circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor;

[0017] Wherein, a first end of the first resistor is connected to the positive bus bar between the battery pack and the relay, a first end of the second resistor is connected to the second end of the first resistor, and a second end of the second resistor is connected to the negative bus bar between the battery pack and the relay, a first end of the third resistor is connected to the positive bus bar between the DC charging port and the relay, a first end of the fourth resistor is connected to the second end of the third resistor, and a second end of the fourth resistor is connected to the negative bus bar between the DC charging port and the relay, a first end of the fifth resistor is connected to the positive bus bar between the DC charging port and the relay, a first end of the sixth resistor is connected to the second end of the fifth resistor, and a second end of the sixth resistor is connected to the negative bus bar between the DC charging port and the relay, a first end of the seventh resistor is connected to the second end of the first resistor and the second end of the third resistor, a first end of the eighth resistor is connected to the second end of the seventh resistor, and a second end of the eighth resistor is connected to the negative bus bar between the battery pack and the relay;

[0018] The first input terminal of one of the comparator modules is connected between the seventh resistor and the eighth resistor, and the first input terminal of another of the comparator modules is connected between the fifth resistor and the sixth resistor.

[0019] According to an embodiment of the present invention, a relay adhesion detection method is provided, which is applied to the relay adhesion detection circuit described in any of the above embodiments, and the relay adhesion detection method includes:

[0020] Generate a reference signal and send it to the comparator module;

[0021] receiving a comparison signal output by the comparator module based on the divided voltage across the relay and the reference signal;

[0022] A sticking state of the relay is determined based on the comparison signal.

[0023] In some implementations, the step of determining the sticking state of the relay based on the comparison signal includes:

[0024] The duty cycle of the comparison signal is compared with a pre-stored correspondence between the duty cycle and the sticking state of the relay, and the sticking state of the relay is determined according to the comparison result.

[0025] According to an embodiment of the present invention, a controller is provided, which includes a memory and a processor, wherein the memory stores a computer program, and when the program is executed by the processor, the steps of the relay adhesion detection method described in any of the above embodiments can be implemented.

[0026] According to an embodiment of the present invention, a computer-readable storage medium is provided for storing a computer program, wherein when the program is executed by a computer or a processor, the steps of the relay adhesion detection method described in any of the above embodiments are implemented.

[0027] According to an embodiment of the present invention, a vehicle is provided, which includes the relay adhesion detection circuit described in any one of the above-mentioned embodiments.

[0028] Compared with the prior art, the present invention has obvious advantages and beneficial effects. By means of the above technical scheme, the relay adhesion detection circuit, relay adhesion detection method and vehicle of the present invention can achieve considerable technical advancement and practicality, and have wide industrial utilization value, and have at least the following advantages:

[0029] The relay adhesion detection circuit of the present invention does not need to perform high voltage sampling during the detection process, and only needs to determine the adhesion state of the relay by detecting the duty cycle. There is no need to use the expensive isolation operational amplifier in the prior art, which effectively reduces the hardware cost of the detection circuit. In addition, the judgment standard of whether there is adhesion during the detection process will not be adjusted with the change of the DC charging bus voltage, thereby realizing the unification of the detection standards and improving the versatility of the relay adhesion detection circuit.

[0030] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following specifically cites a preferred embodiment and describes it in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A topological schematic diagram of a relay adhesion detection circuit according to an embodiment of the present invention;

[0032] Figure 2 A topological diagram of a triangle wave generating module according to an embodiment of the present invention;

[0033] Figure 3 The figure is a flow chart of a relay adhesion detection method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods and effects of the relay adhesion detection circuit, relay adhesion detection method and vehicle proposed in the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0035] According to an embodiment of the present invention, a relay adhesion detection circuit is provided, and the relay adhesion detection circuit is used to detect the adhesion state of the relay. The relay is arranged in a battery charging circuit of a vehicle. Specifically, Figure 1 As shown, the battery charging circuit of the vehicle has two relays (K1, K2), which are respectively arranged on the positive bus and the negative bus between the battery pack 10 and the DC charging port 20 of the vehicle.

[0036] The relay connected to the positive bus is the first relay K1, and the relay connected to the negative bus is the second relay K2. After receiving the relay adhesion detection instruction, the controller controls the coils of the first relay K1 and the second relay K2 to be in a disconnected state.

[0037] like Figure 1 As shown, a relay adhesion detection circuit according to an embodiment of the present invention includes: a controller uC, two comparator modules (U1, U2) and a voltage divider circuit 30.

[0038] The voltage divider circuit 30 is connected to the positive and negative busbars at both ends of the two relays to divide the voltage at both ends of the two relays (K1, K2). The voltage divider circuit 30 is connected to the positive busbar and the negative busbar between the battery pack 10 of the vehicle and the DC charging port 20, and is distributed at both ends of the two relays (K1, K2). In this embodiment, the two ends of the two relays (K1, K2) are the input and output ends of the relays, wherein the end of the two relays (K1, K2) close to the battery pack 10 of the vehicle is the output end, and the end close to the DC charging port 20 is the input end.

[0039] Two comparator modules (U1, U2) are respectively connected to a voltage divider circuit 30 and a controller uC, wherein first input ends of the two comparator modules (U1, U2) are respectively connected to the voltage divider circuit at both ends of two relays (K1, K2) so as to respectively receive the divided voltages (Vo1, Vo2) at both ends of the two relays (K1, K2); second input ends of the two comparator modules (U1, U2) are respectively connected to the controller uC so as to receive a reference signal Vramp sent by the controller uC; and output ends of the two comparator modules (U1, U2) are respectively connected to the controller uC so as to send comparison signals (d1, d2) outputted from the output ends of the two comparator modules (U1, U2) to the controller uC.

[0040] Specifically, the first input terminals of the two comparator modules (U1, U2) are in-phase terminals, and the second input terminals of the two comparator modules (U1, U2) are inverting terminals.

[0041] In one embodiment, if Figure 1As shown, the voltage divider circuit 30 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7 and an eighth resistor R8.

[0042] The first end of the first resistor R1 is connected to the positive bus between the battery pack 10 and the two relays (K1, K2), the first end of the second resistor R2 is connected to the second end of the first resistor R1, the second end of the second resistor R2 is connected to the negative bus between the battery pack 10 and the two relays (K1, K2), the first end of the third resistor R3 is connected to the positive bus between the DC charging port 20 and the two relays (K1, K2), the first end of the fourth resistor R4 is connected to the second end of the third resistor R3, and the second end of the fourth resistor R4 is connected to the negative bus between the DC charging port 20 and the two relays (K1, K2). The first end of the fifth resistor R5 is connected to the positive bus between the DC charging port 20 and the two relays (K1, K2), the first end of the sixth resistor R6 is connected to the second end of the fifth resistor R5, and the second end of the sixth resistor R6 is connected to the negative bus between the DC charging port 20 and the two relays (K1, K2), the first end of the seventh resistor R7 is connected to the second end of the first resistor R1 and the second end of the third resistor R3, the first end of the eighth resistor R8 is connected to the second end of the seventh resistor R7, and the second end of the eighth resistor R8 is connected to the negative bus between the battery pack 10 and the two relays (K1, K2).

[0043] In this embodiment, the resistance values ​​of the first resistor R1 to the eighth resistor R8 can be selected according to actual use requirements, and the present invention is not limited to the specific resistance values ​​of the first resistor R1 to the eighth resistor R8.

[0044] In this embodiment, the two comparator modules (U1, U2) include a first comparator module U1 and a second comparator module U2, wherein the first input end of the first comparator module U1 is connected between the seventh resistor R7 and the eighth resistor R8, and the first input end of the second comparator module U2 is connected between the fifth resistor R5 and the sixth resistor R6.

[0045] Specifically, the first input end of the first comparator module U1 is simultaneously connected to the second end of the seventh resistor R7 and the first end of the eighth resistor R8 to collect the divided voltage Vo1 of the output end (the end of the relay close to the battery pack) of the two relays (K1, K2). The first input end of the second comparator module U2 is simultaneously connected to the second end of the fifth resistor R5 and the first end of the sixth resistor R6 to collect the divided voltage Vo2 of the input end (the end of the relay close to the DC charging port) of the two relays (K1, K2).

[0046] In this embodiment, when the first relay K1 and the second relay K2 are in different open and closed states, the divided voltage Vo2 at the input end and the divided voltage Vo1 at the output end of the two relays (K1, K2) vary according to the different open and closed states of the first relay K1 and the second relay K2, as follows:

[0047] When the first relay K1 and the second relay K2 are both in the disconnected state, the divided voltage Vo2 at the input end and the divided voltage Vo1 at the output end of the two relays (K1, K2) are as follows:

[0048]

[0049] Vo2=0

[0050] When the first relay K1 is in a closed state and the second relay K2 is in an open state, the divided voltage Vo2 at the input end of the relay and the divided voltage Vo1 at the output end are as follows:

[0051]

[0052] When the first relay K1 is in an open state and the second relay K2 is in a closed state, the divided voltage Vo2 at the input end of the relay and the divided voltage Vo1 at the output end are as follows:

[0053]

[0054] When the first relay K1 and the second relay K2 are both in a closed state, the divided voltage Vo2 at the input end of the relay and the divided voltage Vo1 at the output end are expressed as follows:

[0055]

[0056] In the above formula for calculating the divided voltage Vo2 at the input end and the divided voltage Vo1 at the output end of the two relays ( K1 , K2 ), V_HV is the voltage of the battery pack 10 .

[0057] The controller uC is configured to generate a reference signal Vramp and send the generated reference signal Vramp to two comparator modules (U1, U2) respectively, and receive comparison signals (d1, d2) output by the two comparator modules (U1, U2), and judge the adhesion state of the two relays (K1, K2) based on the duty cycle of the comparison signals (d1, d2).

[0058] In one embodiment, the controller uC generates a reference signal Vramp having a preset duty cycle and a preset frequency through the PWM1 port and the PWM2 port, respectively, and sends the reference signal Vramp to the second input terminals of the two comparator modules (U1, U2), respectively. The two comparator modules (U1, U2) output comparison signals (d1, d2) according to the divided voltages (Vo1, Vo2) received across the two relays (K1, K2) and the reference signal Vramp generated by the controller uC, respectively. The controller uC receives the comparison signals (d1, d2) output by the two comparator modules (U1, U2) through the CAP1 port and the CAP2 port, respectively, and then the controller uC determines the adhesion state of the two relays (K1, K2) according to the duty cycle of the comparison signals (d1, d2).

[0059] Preferably, the preset duty cycle of the reference signal Vramp is 50%, and the preset frequency matches the voltage of the battery pack 10 .

[0060] In a specific embodiment, the voltage of the battery pack 10 is variable, and the processor (such as IPU, i.e. Inter-Processor Unit, infrastructure processor) obtains the voltage of the battery pack 10 in the battery management system through the CAN bus, and the controller calculates the preset frequency of the reference signal Vramp according to 930 / V_HV*500Hz.

[0061] For example, when the voltage of the battery pack is 930V, the preset frequency of the reference signal Vramp is 500Hz, and the preset duty cycle is 50%; when the voltage of the battery pack 10 is 800V, the preset frequency of the reference signal Vramp is 581Hz, and the preset duty cycle is 50%; when the voltage of the battery pack 10 is 700V, the preset frequency of the reference signal Vramp is 664Hz, and the preset duty cycle is 50%; when the voltage of the battery pack 10 is 600V, the preset frequency of the reference signal Vramp is 775Hz, and the preset duty cycle is 50%; when the voltage of the battery pack 10 is 500V, the preset frequency of the reference signal Vramp is 930Hz, and the preset duty cycle is 50%; when the voltage of the battery pack 10 is 465V, the preset frequency of the reference signal Vramp is 1000Hz, and the preset duty cycle is 50%.

[0062] In one embodiment, the controller uC is configured to compare the duty cycle of the comparison signal (d1, d2) with the pre-stored correspondence between the duty cycle and the adhesion state of the relay after receiving the comparison signal (d1, d2), and determine the adhesion state of the two relays (K1, K2) based on the comparison result.

[0063] In this embodiment, the corresponding relationship between the duty cycle and the sticking state of the relay is pre-selected and stored in the controller uC.

[0064] For example, when the voltage of the battery pack 10 is 900V and the frequency of the reference signal Vramp is 500 Hz, the corresponding relationship is as shown in Table 1.

[0065] Table 1

[0066] No. K1 K2 d1(duty) d2(duty) Adhesion state 1 0 0 0.585 0.093 No adhesion 2 0 1 0.82 0.355 K2 Adhesion 3 1 0 0.466 0.3 K1 adhesion 4 1 1 0.65 0.82 K1 and K2 adhesion

[0067] When the voltage of the battery pack 10 is 800V and the frequency of the reference signal Vramp is 581 Hz, the corresponding relationship is shown in Table 2.

[0068] Table 2

[0069] No. K1 K2 d1(duty) d2(duty) Adhesion state 1 0 0 0.583 0.095 No adhesion 2 0 1 0.82 0.356 K2 Adhesion 3 1 0 0.466 0.3 K1 adhesion 4 1 1 0.65 0.82 K1 and K2 adhesion

[0070] When the voltage of the battery pack 10 is 700V and the frequency of the reference signal Vramp is 664 Hz, the corresponding relationship is shown in Table 3.

[0071] Table 3

[0072] No. K1 K2 d1(duty) d2(duty) Adhesion state 1 0 0 0.586 0.092 No adhesion 2 0 1 0.819 0.355 K2 Adhesion 3 1 0 0.466 0.3 K1 adhesion 4 1 1 0.65 0.82 K1 and K2 adhesion

[0073] When the voltage of the battery pack 10 is 600V and the frequency of the reference signal Vramp is 775Hz, the corresponding relationship is shown in Table 4.

[0074] Table 4

[0075] No. K1 K2 d1(duty) d2(duty) Adhesion state 1 0 0 0.585 0.094 No adhesion 2 0 1 0.818 0.353 K2 Adhesion 3 1 0 0.466 0.3 K1 adhesion 4 1 1 0.65 0.82 K1 and K2 adhesion

[0076] When the voltage of the battery pack 10 is 500V and the frequency of the reference signal Vramp is 930Hz, the corresponding relationship is shown in Table 5.

[0077] Table 5

[0078]

[0079]

[0080] When the voltage of the battery pack 10 is 465V and the frequency of the reference signal Vramp is 1000 Hz, the corresponding relationship is shown in Table VI.

[0081] Table 6

[0082] No. K1 K2 d1(duty) d2(duty) Adhesion state 1 0 0 0.584 0.093 No adhesion 2 0 1 0.817 0.353 K2 Adhesion 3 1 0 0.466 0.3 K1 adhesion 4 1 1 0.65 0.82 K1 and K2 adhesion

[0083] In the above table, d1(duty) and d2(duty) respectively represent the duty cycles of the comparison signals (d1, d2) outputted by the two comparator modules (U1, U2).

[0084] In this embodiment, after the controller uC receives the comparison signals (d1, d2) sent by the two comparator modules (U1, U2), it compares them with the correspondence between the duty cycle and the adhesion state of the relay pre-stored in the controller uC (as shown in Tables 1 to 6). When the duty cycle of the two comparison signals (d1, d2) is the same as a group of duty cycles in the corresponding relationship, it can be determined that the adhesion state corresponding to the group of duty cycles is the adhesion state of the two relays (K1, K2).

[0085] In one embodiment, if Figure 1 As shown, the relay adhesion detection circuit also includes two digital isolator modules (U3, U4), which are respectively connected to the two comparator modules (U1, U2), and the two digital isolator modules (U3, U4) are both connected to the controller uC.

[0086] In this embodiment, the two digital isolator modules (U3, U4) are a first digital isolator module U3 and a second digital isolator module U4, wherein the reference signal Vramp generated by the controller uC is transmitted to the first comparator module U1 after passing through the first digital isolator module U3, and is transmitted to the second comparator module U2 after passing through the second digital isolator module U4. The first comparison signal d1 output by the first comparator module U1 is transmitted to the controller uC through the first digital isolator module U3, and the second comparison signal d2 output by the second comparator module U2 is transmitted to the controller uC through the second digital isolator module U2. Through the setting of the digital isolator modules (U3, U4), the PWM type comparison signals (d1, d2) output by the comparator modules (U1, U2) can be converted into digital type comparison signals (d1, d2) that share the same ground with the controller uC.

[0087] In one embodiment, the relay adhesion detection circuit also includes two triangular wave generating modules (U5, U6), the two triangular wave generating modules (U5, U6) are respectively connected to the second input ends of the two comparator modules (U1, U2), and the two triangular wave generating modules (U5, U6) are respectively connected to the two digital isolator modules (U3, U4).

[0088] In this embodiment, the two triangle wave generating modules (U5, U6) are the first triangle wave generating module U5 and the second triangle wave generating module U6. The square wave signal generated by the controller uC passes through the first digital isolator module U3 and the second digital isolator module U4 respectively, and is transmitted to the first triangle wave generating module U5 and the second triangle wave generating module U6 accordingly, so that the square wave signal is converted into a triangle wave signal through the triangle wave generating modules (U5, U6), and then the triangle wave signal is sent to the corresponding first comparator module U1 and the second comparator module U2, and the triangle wave signal is used as the reference signal Vramp of the second input end of the two comparator modules (U1, U2).

[0089] Alternatively, if Figure 2 As shown, the triangular wave generating module (U5, U6) includes: an operational amplifier U7, a ninth resistor R9, a tenth resistor R10 and a capacitor filter Cf. The ninth resistor R9 is connected to the first input terminal of the operational amplifier U7, the tenth resistor R10 is connected to the second input terminal of the operational amplifier U7, and the capacitor filter Cf is respectively connected to the second input terminal of the operational amplifier U7 and the output terminal of the operational amplifier U7.

[0090] like Figure 2 As shown, the second input terminal of the operational amplifier U7 inputs a square wave signal Vin with the same amplitude, a frequency that changes linearly with the voltage of the battery pack 10, and a duty cycle of 50%. The output terminal of the operational amplifier U7 outputs a reference signal Vramp.

[0091]

[0092] It can be seen from the above formula that when the ninth resistor R9 and the capacitor filter Cf are fixed values, the reference signal also changes linearly according to the frequency, that is, the reference signal Vramp input to the second input terminals of the two comparator modules (U1, U2) changes linearly with the voltage of the battery pack.

[0093] When the above-mentioned first relay K1 and the second relay K2 are in different open and closed states, the changes in the divided voltages at the input ends and the divided voltages (Vo1, Vo2) at the output ends of the two relays (K1, K2) show that the divided voltage Vo2 at the input ends and the divided voltage Vo1 at the output ends of the two relays (K1, K2) also change linearly with the voltage of the battery pack 10. Therefore, when the reference signals Vramp and the divided voltages Vo1, Vo2) respectively inputted at the first input ends and the second input ends of the two comparator modules (U1, U2) change linearly with the voltage of the battery pack 10, the duty cycle of the comparison signals (d1, d2) outputted by the two comparator modules (U1, U2) can remain unchanged. Based on this, the judgment standard of the adhesion state of the relay does not need to be adjusted as the voltage of the DC bus changes.

[0094] In one embodiment, if Figure 1 As shown, the relay adhesion detection circuit also includes a pair of power supplies VCC1 and GND1 with the negative pole of the battery charger 10 as the reference end, a group of power supplies VCC2 and GND2 with the negative end of the DC fast charging port 20 as the reference end; and a group of power supplies VCC3 and GND3 with the ground of the controller uC as the reference end.

[0095] According to another embodiment of the present invention, a relay adhesion detection method is provided, which is applied to the relay adhesion detection circuit described in any of the above embodiments. The relay adhesion detection method is used to detect the adhesion state of the relay. The relay is arranged in a battery charging circuit of a vehicle. Specifically, Figure 1 As shown, the battery charging circuit of the vehicle has two relays (K1, K2), which are respectively arranged on the positive bus and the negative bus between the battery pack 10 and the DC charging port 20 of the vehicle.

[0096] The relay connected to the positive bus is the first relay K1, and the relay connected to the negative bus is the second relay K2. After receiving the relay adhesion detection instruction, the controller controls the coils of the first relay K1 and the second relay K2 to be in a disconnected state.

[0097] like Figure 3 As shown, the relay adhesion detection method includes:

[0098] Step S10, generating a reference signal and sending it to the comparator module.

[0099] In this step, the controller uC generates a reference signal Vramp having a preset duty cycle and a preset frequency through the PWM1 port and the PWM2 port, and sends the reference signal Vramp to the second input terminals of the two comparator modules (U1, U2).

[0100] Preferably, the preset duty cycle of the reference signal Vramp is 50%, and the preset frequency matches the voltage of the battery pack 10 .

[0101] In a specific embodiment, the voltage of the battery pack 10 is variable, and the processor (such as IPU, i.e. Inter-Processor Unit, infrastructure processor) obtains the voltage of the battery pack 10 in the battery management system through the CAN bus, and the controller calculates the preset frequency of the reference signal Vramp according to 930 / V_HV*500Hz.

[0102] For example, when the voltage of the battery pack is 930V, the preset frequency of the reference signal Vramp is 500Hz, and the preset duty cycle is 50%; when the voltage of the battery pack 10 is 800V, the preset frequency of the reference signal Vramp is 581Hz, and the preset duty cycle is 50%; when the voltage of the battery pack 10 is 700V, the preset frequency of the reference signal Vramp is 664Hz, and the preset duty cycle is 50%; when the voltage of the battery pack 10 is 600V, the preset frequency of the reference signal Vramp is 775Hz, and the preset duty cycle is 50%; when the voltage of the battery pack 10 is 500V, the preset frequency of the reference signal Vramp is 930Hz, and the preset duty cycle is 50%; when the voltage of the battery pack 10 is 465V, the preset frequency of the reference signal Vramp is 1000Hz, and the preset duty cycle is 50%.

[0103] Step S20, receiving a comparison signal output by the comparator module based on the divided voltage across the relay and the reference signal.

[0104] In this step, two comparator modules (U1, U2) output comparison signals (d1, d2) according to the divided voltages (Vo1, Vo2) received across the two relays (K1, K2) and the reference signal Vramp generated by the controller uC.

[0105] Among them, the divided voltage (Vo1, Vo2) across the two relays (K1, K2) is the divided voltage Vo1 at the output end (the end of the relay close to the battery pack) of the two relays (K1, K2) and the divided voltage Vo2 at the input end (the end of the relay close to the DC charging port) of the two relays (K1, K2).

[0106] Specifically, when the first relay K1 and the second relay K2 are in different open and closed states, the divided voltage Vo2 at the input end and the divided voltage Vo1 at the output end of the two relays (K1, K2) vary according to the different open and closed states of the first relay K1 and the second relay K2, as follows:

[0107] When the first relay K1 and the second relay K2 are both in the disconnected state, the divided voltage Vo2 at the input end and the divided voltage Vo1 at the output end of the two relays (K1, K2) are as follows:

[0108]

[0109] Vo2=0

[0110] When the first relay is in the closed state and the second relay is in the open state, the divided voltage at the input end and the divided voltage at the output end of the relay are as follows:

[0111]

[0112] When the first relay is in the open state and the second relay is in the closed state, the divided voltage at the input end and the divided voltage at the output end of the relay are as follows:

[0113]

[0114] When the first relay and the second relay are both in the closed state, the divided voltage at the input end and the divided voltage at the output end of the relay are as follows:

[0115]

[0116] In the above formula for calculating the divided voltage Vo2 at the input end and the divided voltage Vo1 at the output end of the two relays ( K1 , K2 ), V_HV is the voltage of the battery pack 10 .

[0117] Step S30, determining the sticking state of the relay based on the comparison signal.

[0118] In this step, the controller uC receives the comparison signals (d1, d2) output by the two comparator modules (U1, U2) through the CAP1 port and the CAP2 port respectively, and then the controller uC determines the adhesion state of the two relays (K1, K2) according to the duty cycle of the comparison signals (d1, d2).

[0119] In one embodiment, step S30 includes: comparing the duty cycle of the comparison signal with a pre-stored correspondence between the duty cycle and the sticking state of the relay, and determining the sticking state of the relay according to the comparison result.

[0120] In this embodiment, the controller uC pre-selects and stores the corresponding relationship between the duty cycle and the sticking state of the relay, as shown in Tables 1 to 6 above.

[0121] After the controller uC receives the comparison signals (d1, d2) sent by the two comparator modules (U1, U2), it compares them with the correspondence between the duty cycle and the adhesion state of the relay pre-stored in the controller uC (as shown in Tables 1 to 6). When the duty cycle of the two comparison signals (d1, d2) is the same as a group of duty cycles in the corresponding relationship, it can be determined that the adhesion state corresponding to the group of duty cycles is the adhesion state of the two relays (K1, K2).

[0122] The relay adhesion detection circuit of the present invention does not need to perform high voltage sampling during the detection process, and only needs to determine the adhesion state of the relay by detecting the duty cycle. There is no need to use the expensive isolation operational amplifier in the prior art, which effectively reduces the hardware cost of the detection circuit. In addition, the judgment standard of whether there is adhesion during the detection process will not be adjusted with the change of the DC charging bus voltage, thereby realizing the unification of the detection standards and improving the versatility of the relay adhesion detection circuit.

[0123] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A relay adhesion detection circuit, characterized in that: The relays are respectively connected to the positive and negative busbars between the DC charging port and the battery pack of the vehicle, and the relay adhesion detection circuit includes: a controller, two comparator modules and a voltage divider circuit; Wherein, the voltage divider circuit is connected to the positive and negative busbars at both ends of the two relays to divide the voltage at both ends of the relays, and the two comparator modules are respectively connected to the voltage divider circuit and the controller; Wherein, the first input ends of the two comparator modules respectively receive the divided voltages at both ends of the relay, the second input ends of the two comparator modules respectively receive the reference signals sent by the controller, and the output ends of the two comparator modules output comparison signals to the controller; The controller is configured to generate the reference signal and send it to the comparator module, receive the comparison signal output by the comparator module, and determine the sticking state of the relay based on the duty cycle of the comparison signal.

2. The relay adhesion detection circuit according to claim 1, characterized in that: It also includes two digital isolator modules, which are respectively connected to the two comparator modules, and the two digital isolator modules are both connected to the controller, so that the reference signal is transmitted to the comparator module after passing through the digital isolator module, and the comparison signal is transmitted to the controller through the digital isolator module.

3. The relay adhesion detection circuit according to claim 2, characterized in that: It also includes two triangle wave generating modules, which are respectively connected to the second input ends of the two comparator modules, and the two triangle wave generating modules are respectively connected to the two digital isolator modules; The reference signal generated by the controller is a square wave signal having a preset duty cycle and a preset frequency; After the triangular wave generating module converts the square wave signal into a triangular wave signal, the triangular wave signal is sent to the comparator module.

4. The relay adhesion detection circuit according to claim 3, characterized in that: The triangle wave generating module comprises: an operational amplifier, a ninth resistor, a tenth resistor and a capacitor filter; The ninth resistor is connected to the first input terminal of the operational amplifier, the tenth resistor is connected to the second input terminal of the operational amplifier, and the capacitor filter is respectively connected to the second input terminal of the operational amplifier and the output terminal of the operational amplifier.

5. The relay adhesion detection circuit according to claim 3 or 4, characterized in that: The duty cycle of the comparison signal output by the comparator module does not change with the voltage of the battery pack.

6. The relay adhesion detection circuit according to any one of claims 1 to 4, characterized in that: The controller is configured to compare the duty cycle of the comparison signal with a pre-stored correspondence between the duty cycle and the sticking state of the relay after receiving the comparison signal, and determine the sticking state of the relay according to the comparison result.

7. The relay adhesion detection circuit according to claim 1, characterized in that: The voltage divider circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and an eighth resistor; Wherein, a first end of the first resistor is connected to the positive bus bar between the battery pack and the relay, a first end of the second resistor is connected to the second end of the first resistor, and a second end of the second resistor is connected to the negative bus bar between the battery pack and the relay, a first end of the third resistor is connected to the positive bus bar between the DC charging port and the relay, a first end of the fourth resistor is connected to the second end of the third resistor, and a second end of the fourth resistor is connected to the negative bus bar between the DC charging port and the relay, a first end of the fifth resistor is connected to the positive bus bar between the DC charging port and the relay, a first end of the sixth resistor is connected to the second end of the fifth resistor, and a second end of the sixth resistor is connected to the negative bus bar between the DC charging port and the relay, a first end of the seventh resistor is connected to the second end of the first resistor and the second end of the third resistor, a first end of the eighth resistor is connected to the second end of the seventh resistor, and a second end of the eighth resistor is connected to the negative bus bar between the battery pack and the relay; The first input terminal of one of the comparator modules is connected between the seventh resistor and the eighth resistor, and the first input terminal of another of the comparator modules is connected between the fifth resistor and the sixth resistor.

8. A relay adhesion detection method, characterized in that: The relay adhesion detection circuit applied to any one of claims 1 to 6, the relay adhesion detection method comprising: Generate a reference signal and send it to the comparator module; receiving a comparison signal output by the comparator module based on the divided voltage across the relay and the reference signal; A sticking state of the relay is determined based on the comparison signal.

9. The relay adhesion detection method according to claim 8, characterized in that: The step of determining the adhesion state of the relay based on the comparison signal comprises: The duty cycle of the comparison signal is compared with a pre-stored correspondence between the duty cycle and the sticking state of the relay, and the sticking state of the relay is determined according to the comparison result.

10. A vehicle, characterized in that: The invention comprises the relay adhesion detection circuit according to any one of claims 1 to 7.

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