Relay adhesion detection circuit, method and battery management system

Abstract

The present invention provides a relay adhesion detection circuit, method and battery management system, the circuit comprising: one end of a first voltage-dividing resistor is connected to a circuit between the other end of a first relay to be tested and a positive output end of a circuit, the other end of the first voltage-dividing resistor is connected to one end of a first control switch, and the other end of the first control switch is connected to an input end of a first channel; the output end of a reference circuit is connected to one end of a first sampling resistor, the other end of the first sampling resistor is connected to one end of a second control switch, the other end of the second control switch is connected to one end of a second voltage-dividing resistor, and the other end of the second voltage-dividing resistor is connected to a circuit between the other end of a second relay to be tested and a negative output end; the other end of the first sampling resistor is also connected to the input end of a second AD channel. After applying the present invention, it is possible to determine whether the first relay to be tested and the second relay to be tested are adhered without cooperating with other relays. When the load also has voltage, the relay adhesion state will not be misjudged.

Description

Technical Field

[0001] The present invention relates to the field of relay adhesion detection, and in particular to a relay adhesion detection circuit and method and a battery management system for an energy storage battery system and an electric vehicle system. Background Art

[0002] The energy storage battery system includes modules such as battery modules, high-voltage boxes and BMS. With the increasing popularity of energy storage battery system applications, the safety requirements of battery systems are also increasing. In particular, judging whether the high-voltage relay is sticking is very important to system safety.

[0003] In the energy storage battery system, the BMS is responsible for detecting the adhesion state of the high-voltage relay. There are three mainstream detection methods: First, the terminal voltage detection method, that is, through the method of resistor voltage division, the voltage at the outer ends of the positive and negative high-voltage relays or the voltage of the positive high-voltage relay outer end to the negative pole of the battery is collected, and then the on-off state of the high-voltage relay is judged by the voltage size; second, the current detection method, that is, the on-off state of the high-voltage relay is detected by external current detection devices at both ends of the high-voltage relay; third, the pulse detection method, that is, by injecting a pulse signal into the high-voltage relay circuit to judge the on-off state of the high-voltage relay.

[0004] When detecting the sticking state of the total negative relay of the energy storage battery system, the traditional relay sticking detection technology often needs to cooperate by controlling the repeated opening and closing of other relays. In addition, before the high voltage of the energy storage battery system is powered on, if the load also has voltage, it is easy to misjudge the sticking state of the relay. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a relay adhesion detection circuit, method and battery management system, which can detect the adhesion state of the relay without repeatedly opening and closing other relays.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: a relay adhesion detection circuit is provided, including a first relay to be tested T1 connected in series between a positive terminal of a battery and one end of a load and a second relay to be tested T2 connected in series between a negative terminal of the battery and the other end of the load, and also including a first AD channel, a second AD channel, a reference circuit, a first voltage-dividing resistor R1, a second voltage-dividing resistor R4, a first sampling resistor R3, a first control switch K1 and a second control switch K2;

[0007] One end of the first voltage-dividing resistor R1 is connected to a common connection point of the first relay T1 to be tested and the load, the other end of the first voltage-dividing resistor R1 is connected to one end of the first control switch K1, and the other end of the first control switch K1 is connected to an input end of the first AD channel;

[0008] The output end of the reference circuit is connected to one end of the first sampling resistor R3, the other end of the first sampling resistor R3 is connected to one end of the second control switch K2, the other end of the second control switch K2 is connected to one end of the second voltage-dividing resistor R4, and the other end of the second voltage-dividing resistor R4 is connected to the common connection point of the second relay to be tested T2 and the load; the other end of the first sampling resistor R3 is also connected to the input end of the second AD channel.

[0009] Optionally, the relay adhesion detection circuit further includes a second sampling resistor R2, a differential amplifier circuit and a third AD channel, the other end of the first control switch K1 is also connected to one end of the second sampling resistor R2, and the other end of the second sampling resistor R2 is also connected to one end of the first sampling resistor R3;

[0010] The differential amplifier circuit includes a first differential amplifier input terminal, a second differential amplifier input terminal and a differential amplifier output terminal; the other end of the first control switch K1 is also connected to the first differential amplifier input terminal, the other end of the first sampling resistor R3 is connected to the second differential amplifier input terminal, and the differential amplifier output terminal is connected to the third AD channel.

[0011] Optionally, the relay adhesion detection circuit further includes a second sampling resistor R2, a differential amplifier circuit and a third AD channel, the other end of the first control switch K1 is also connected to one end of the second sampling resistor R2, and the other end of the second sampling resistor R2 is also connected to one end of the first sampling resistor R3;

[0012] The differential amplifier circuit includes a first differential amplifier input terminal, a second differential amplifier input terminal and a differential amplifier output terminal; the other end of the first control switch K1 is also connected to the first differential amplifier input terminal, the output end of the reference circuit is connected to the second differential amplifier input terminal, and the differential amplifier output terminal is connected to the third AD channel.

[0013] A second aspect of the present application provides a relay adhesion detection method, which uses a relay adhesion detection circuit and includes the following steps:

[0014] Disconnect the first control switch K1, close the second control switch K2, and obtain the first link voltage and the output voltage of the reference circuit; wherein the first link voltage is the sampled voltage of the other end of the first sampling resistor R3;

[0015] Closing the first control switch K1 and the second control switch K2 to obtain the output voltage of the reference circuit;

[0016] It is determined that the second relay to be tested T2 is stuck according to the first link voltage and the output voltage of the reference circuit.

[0017] Further, the relay adhesion detection circuit is provided with a differential amplifier circuit; after determining that the second relay to be tested T2 is adhered, the method further comprises the following steps:

[0018] The first control switch K1 is closed, and the second control switch K2 is opened to obtain a second link voltage; wherein the second link voltage is a sampled voltage at the other end of the first control switch K1;

[0019] Applying the second link voltage to compare with the output voltage of the reference circuit;

[0020] If the second link voltage is greater than the output voltage of the reference circuit, the external terminal voltage is calculated by applying the second link voltage, the output voltage of the reference circuit, and the magnification factor of the difference between the first link voltage and the second link voltage of the differential amplifier circuit;

[0021] The external terminal voltage and the voltage across the circuit battery are used to determine whether the first relay to be tested T1 is stuck. If the external terminal voltage is equal to the voltage across the battery, the first relay to be tested T1 is stuck.

[0022] Furthermore, the above relay adhesion detection method further includes the following steps:

[0023] Closing the first control switch K1 and opening the second control switch K2 to obtain the second link voltage;

[0024] If the second link voltage is equal to the output voltage of the reference circuit, the first relay to be tested T1 is not stuck.

[0025] Furthermore, if the first relay to be tested T1 and the second relay to be tested T2 are not adhered, the following steps are also included:

[0026] Close the first control switch K1 and the second control switch K2 to obtain the output voltage of the differential amplifier circuit, and obtain the first link voltage and the second link voltage;

[0027] The external terminal voltage is calculated by using the output voltage of the differential amplifier circuit and the amplification factor of the differential amplifier circuit for the difference between the first link voltage and the second link voltage.

[0028] Furthermore, if the first relay to be tested T1 is adhered and the second relay to be tested T2 is not adhered, the method further includes the following steps:

[0029] The external terminal voltage is calculated by applying the first link voltage, the second link voltage, and the output voltage of the reference circuit.

[0030] Further, if the first relay to be tested T1 is not adhered and the second relay to be tested T2 is adhered, the total output voltage of the circuit is 0V.

[0031] The present application also provides a battery management system, including the above-mentioned relay adhesion detection circuit. In the present invention, when the first relay to be tested T1 and the second relay to be tested T2 are not controlled, the sampling values ​​are respectively obtained by the operation of the first control switch K1 and the second control switch K2, and then the sampling values ​​are compared with the corresponding threshold values ​​to determine the adhesion state of the first relay to be tested T1 and the second relay to be tested T2. After applying the present invention, it is possible to determine whether the first relay to be tested T1 and the second relay to be tested T2 are adhered without cooperating with other relays. If the load also has voltage, it is not easy to cause misjudgment of the relay adhesion state. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The specific structure of the present invention is described in detail below with reference to the accompanying drawings

[0033] Figure 1 A module block diagram of a first embodiment of a relay adhesion detection circuit of the present invention;

[0034] Figure 2 4 is a block diagram of a third embodiment of a relay adhesion detection circuit according to the present invention;

[0035] Figure 3 Flow chart of a first embodiment of a relay adhesion detection method according to the present invention;

[0036] Figure 4 is a flow chart of a second embodiment of a relay adhesion detection method of the present invention;

[0037] Figure 5 It is a flow chart of a first embodiment of a relay adhesion detection method applied in a battery management system of the present invention;

[0038] Figure 6 It is a flow chart of a second embodiment of a relay adhesion detection method applied in a battery management system of the present invention;

[0039] 1-first AD channel; 2-second AD channel; 3-third AD channel; 4-reference circuit; 5-differential amplifier circuit. DETAILED DESCRIPTION

[0040] In order to explain the technical content, structural features, achieved objectives and effects of the present invention in detail, the following is a detailed description in conjunction with the implementation methods and the accompanying drawings.

[0041] See also Figure 1 ; Figure 1 It is a module block diagram of the first embodiment of the relay adhesion detection circuit of the present invention. Figure 1 Middle,U b is the battery voltage, i.e. the total input voltage of the relay sticking detection circuit; U L is the load voltage, i.e. the total output voltage of the relay adhesion detection circuit, which can also be called the external terminal voltage; T1 is the total positive relay, i.e. the first relay to be tested; T2 is the total negative relay, i.e. the second relay to be tested; U LINK+ is the voltage of the positive end of the load relative to the negative end of the battery; U LINK - is the voltage of the negative end of the load relative to the negative end of the battery; GND inside the board is the negative end of the battery BAT-. AD channel is the analog sampling channel.

[0042] K1 is the switch on the sampling resistor bridge arm of the load positive end (LINK+). The voltage divider resistor on the bridge arm is R1, the sampling resistor is R2, and V link+ is the sampling point on the bridge arm, that is, the second link voltage; K2 is the relay on the bridge arm of the sampling resistor at the negative end of the load (LINK-), the voltage divider resistor on the bridge arm is R1, the sampling resistor is R3, V link - is the sampling point on the bridge arm, i.e., the first link voltage; V REF is the reference voltage, provided by the reference circuit; V L V link+ With V link -The differential sampling circuit output signal.

[0043] The present application provides a relay adhesion detection circuit, including a first relay to be tested T1 connected in series between a positive terminal of a battery and one end of a load, and a second relay to be tested T2 connected in series between a negative terminal of the battery and the other end of the load, and also including a first AD channel 1, a second AD channel 2, a reference circuit 4, a first voltage-dividing resistor R1, a second voltage-dividing resistor R4, a first sampling resistor R3, a first control switch K1, and a second control switch K2;

[0044] One end of the first voltage-dividing resistor R1 is connected to the common connection point of the first relay T1 to be tested and the load, the other end of the first voltage-dividing resistor R1 is connected to one end of the first control switch K1, and the other end of the first control switch K1 is connected to the input end of the first AD channel 1;

[0045] The output end of the reference circuit 4 is connected to one end of the first sampling resistor R3, the other end of the first sampling resistor R3 is connected to one end of the second control switch K2, the other end of the second control switch K2 is connected to one end of the second voltage-dividing resistor R4, and the other end of the second voltage-dividing resistor R4 is connected to the common contact point of the second relay to be tested T2 and the load; the other end of the first sampling resistor R3 is also connected to the input end of the second AD channel 2.

[0046] In the present invention, when the first relay to be tested T1 and the second relay to be tested T2 are not controlled, the sampling values ​​are respectively obtained by operating the first control switch K1 and the second control switch K2, and then the sampling values ​​are compared with the corresponding threshold values ​​to determine the adhesion state of the first relay to be tested T1 and the second relay to be tested T2. After the present invention is applied, it is possible to determine whether the first relay to be tested T1 and the second relay to be tested T2 are adhered without cooperating with other relays. If the load also has voltage, it is not easy to cause misjudgment of the relay adhesion state.

[0047] The first link voltage is collected by the second AD channel 2 , and the second link voltage is collected by the first AD channel 1 .

[0048] Optionally, in the second embodiment, the relay adhesion detection circuit further includes a second sampling resistor R2, a differential amplifier circuit 5 and a third AD channel 3, the other end of the first control switch K1 is also connected to one end of the second sampling resistor R2, and the other end of the second sampling resistor R2 is also connected to one end of the first sampling resistor R3;

[0049] The differential amplifier circuit 5 includes a first differential amplifier input terminal, a second differential amplifier input terminal and a differential amplifier output terminal; the other end of the first control switch K1 is also connected to the first differential amplifier input terminal, the other end of the first sampling resistor R3 is connected to the second differential amplifier input terminal, and the differential amplifier output terminal is connected to the third AD channel 3.

[0050] The first link voltage is collected by the second AD channel 2 ; the second link voltage is collected by the first AD channel 1 ; and the output voltage of the differential amplifier circuit 5 is obtained by the third AD channel 3 .

[0051] In this embodiment, the differential amplifier circuit 5 is used to determine whether the first relay to be tested T1 is stuck after determining that the second relay to be tested T2 is not stuck. Then, the corresponding formula is used to determine whether the first relay to be tested T1 is stuck.

[0052] In addition, the differential amplifier circuit 5 can output an analog voltage, and the analog voltage, in combination with a voltage divider resistor and a sampling resistor, and a corresponding calculation formula can be used to obtain an external terminal voltage.

[0053] Optionally, see Figure 2 , Figure 2 The module block diagram of the third embodiment of the relay adhesion detection circuit of the present invention. The above relay adhesion detection circuit also includes a second sampling resistor R2, a differential amplifier circuit 5 and a third AD channel 3, the other end of the first control switch K1 is also connected to one end of the second sampling resistor R2, and the other end of the second sampling resistor R2 is also connected to one end of the first sampling resistor R3;

[0054] The differential amplifier circuit 5 includes a first differential amplifier input terminal, a second differential amplifier input terminal and a differential amplifier output terminal; the other end of the first control switch K1 is also connected to the first differential amplifier input terminal, the output terminal of the reference circuit 4 is connected to the second differential amplifier input terminal, and the differential amplifier output terminal is connected to the third AD channel 3. Among them, the first link voltage is collected by the second AD channel 2; the second link voltage is collected by the first AD channel 1; the output voltage of the differential amplifier circuit 5 is obtained by the third AD channel 3.

[0055] The second and third embodiments can achieve the same technical effect. The technical difference between the two embodiments is only the position where the second differential amplifier input terminal of the differential amplifier circuit 5 is connected. Therefore, the two embodiments need to use different calculation formulas.

[0056] Generally, R1 and R4 can be formed by a combination of multiple resistors connected in series and parallel. The resistance values ​​of R1 and R4 are equal, and R2 and R3 are usually much smaller than R1.

[0057] For a better explanation of the above invention, please refer to Figure 3 , Figure 3 Flow chart of the first embodiment of the relay adhesion detection method of the present invention.

[0058] A second aspect of the present application provides a relay adhesion detection method, which uses a relay adhesion detection circuit and includes the following steps:

[0059] Step S100, disconnect the first control switch K1, close the second control switch K2, obtain the first link voltage and the output voltage of the reference circuit; wherein the first link voltage is the sampling voltage of the other end of the first sampling resistor R3. The first link voltage is collected by the second AD channel 2.

[0060] Step S200, closing the first control switch K1 and the second control switch K2 to obtain the output voltage of the reference circuit;

[0061] Step S300: If the first link voltage and the output voltage of the reference circuit meet a first sticking judgment formula, it is determined that the second relay to be tested T2 is stuck.

[0062] In this embodiment, the resistance values ​​of the first voltage-dividing resistor R1 and the second voltage-dividing resistor R4 are both R1. The first adhesion judgment formula is as follows: V link - = V REF *R1 / (R1+R3);

[0063] Among them, the V link - is the first link voltage, V REFis the output voltage of the reference circuit, R1 is the resistance value of the first voltage-dividing resistor R1, which is also the resistance value of the second voltage-dividing resistor R4, and R3 is the resistance value of the first sampling resistor R3.

[0064] In this embodiment, the relay adhesion detection circuit in any of the above embodiments may be used, and through the above operation, the first link voltage and the output voltage of the reference circuit may be obtained.

[0065] For further information, see Figure 4 , Figure 4 Flow chart of the second embodiment of the relay adhesion detection method of the present invention; the relay adhesion detection circuit in this embodiment is provided with a differential amplifier circuit; if it is determined that the second relay to be tested T2 is adhered, the method further includes the following steps:

[0066] Step S411, obtaining a second link voltage; wherein the second link voltage is a sampled voltage at one end of the second sampling resistor R2;

[0067] Step S412, applying the second link voltage to compare with the output voltage of the reference circuit;

[0068] Step S413, if the second link voltage is greater than the output voltage of the reference circuit, the external terminal voltage is calculated by applying the second link voltage, the output voltage of the reference circuit and the amplification factor of the differential amplifier circuit to the first link voltage and the second link voltage;

[0069] Step S414, applying the external terminal voltage and the voltage across the battery of the circuit to determine whether the first relay to be tested T1 is adhered;

[0070] Step S415: If the external terminal voltage is equal to the voltage across the battery of the circuit, the first relay to be tested T1 is stuck.

[0071] Optionally, in this embodiment, steps S411 to S415 provide a method for determining whether the first relay to be tested T1 is stuck by using the external terminal voltage.

[0072] If steps S411 to S415 are combined with the circuit in the second embodiment of the first aspect of the present application, the calculation formula of the external terminal voltage is as follows:

[0073] U L =(V L / AV REF +V link -)*(R1+R2) / R2+V REF ;

[0074] Among them, U L is the external terminal voltage; V L is the output voltage of the differential amplifier circuit; VREF is the output voltage of the reference circuit; V link - is the first link voltage; R1 is the resistance value of the first voltage-dividing resistor R1, which is also the resistance value of the second voltage-dividing resistor R4; R2 is the resistance value of the second sampling resistor R2. A is the amplification factor of the differential amplifier circuit in the circuit of the second embodiment in the first aspect of the present invention to the first link voltage and the second link voltage, that is, V L =A*(V link+ -V link -), V Link+ is the second link voltage.

[0075] If steps S411 to S415 are combined with the circuit in the third embodiment of the first aspect of the present application, the calculation formula of the external terminal voltage is as follows:

[0076] U L =(R1+R2) / R2*V L / B+V REF ;

[0077] Among them: U L is the external terminal voltage; V L is the output voltage of the differential amplifier circuit; V REF is the output voltage of the reference circuit; V link - is the first link voltage; R1 is the resistance value of the first voltage-dividing resistor R1, which is also the resistance value of the second voltage-dividing resistor R4; R2 is the resistance value of the second sampling resistor R2. Wherein; the resistance value of the second sampling resistor R2 is much smaller than the resistance value R1 of the voltage-dividing resistor. B is the amplification factor of the differential amplifier circuit in the circuit of the third embodiment in the first aspect to the first link voltage and the second link voltage. Wherein:

[0078] V L =B*(V link+ -V REF );

[0079] Among them, V Link+ is the second link voltage.

[0080] In an optional embodiment, the above relay adhesion detection method further includes the following steps:

[0081] Step S511, close the first control switch K1, open the second control switch K2, and obtain the second link voltage;

[0082] Step S512: If the second link voltage is not equal to the output voltage of the reference circuit, the first relay to be tested T1 is stuck.

[0083] In steps S511-S512, the second link voltage and the output voltage of the reference circuit are directly used to determine whether the first relay T1 to be tested is stuck. This has similar technical effects to steps S411-415, and a comparison can be performed to determine whether the first relay T1 to be tested is stuck.

[0084] Furthermore, the above relay adhesion detection method comprises the following steps:

[0085] Step S610: If the first relay to be tested T1 and the second relay to be tested T2 are not adhered, the first control switch K1 and the second control switch K2 are closed to obtain the output voltage of the differential amplifier circuit, the first link voltage and the second link voltage;

[0086] Step S620 , calculating the external terminal voltage by using the output voltage of the differential amplifier circuit and the amplification factor of the differential amplifier circuit to the first link voltage and the second link voltage.

[0087] If the circuit of the second embodiment in the first aspect of the present application uses steps S610 to S620, the calculation formula of the external terminal voltage is as follows:

[0088] U L =(2*R1+R2+R3) / (R2+R3)*V L / A;

[0089] Among them, U L is the external terminal voltage; R1 is the resistance value of the first voltage-dividing resistor R1, which is also the resistance value of the second voltage-dividing resistor R4; R2 is the resistance value of the second sampling resistor R2; R3 is the resistance value of the first sampling resistor R3; V L is the output voltage of the differential amplifier circuit; A is the amplification factor of the differential amplifier circuit to the first link voltage and the second link voltage in the circuit of the second embodiment in the first aspect of the present invention. L =A*(V link+ -V link- ).

[0090] If the circuit of the third embodiment in the first aspect of the present application uses steps S610 to S620, the calculation formula of the external terminal voltage is as follows:

[0091] U L =(R1+R2) / R2*V L / B-(V link- -V REF )*(R1+R3) / R3;

[0092] Among them, U Lis the external terminal voltage; R1 is the resistance value of the first voltage-dividing resistor R1, which is also the resistance value of the second voltage-dividing resistor R4; R2 is the resistance value of the second sampling resistor R2; R3 is the resistance value of the first sampling resistor R3; V link- is the first link voltage; V REF is the output voltage of the reference circuit. B is the amplification factor of the first link voltage and the second link voltage of the differential amplifier circuit in the circuit of the third embodiment within the first aspect of the present application;

[0093] Among them, V L =B*(V link+ -V REF ), V L is the output voltage of the differential amplifier circuit; V link+ is the second link voltage; V REF is the output voltage of the reference circuit.

[0094] Furthermore, the above-mentioned relay adhesion voltage detection method further includes the following steps:

[0095] Step S700: If the first relay to be tested T1 is stuck and the second relay to be tested T2 is not stuck, the first link voltage, the second link voltage, and the output voltage of the reference circuit are obtained to calculate the external terminal voltage.

[0096] It should be understood that in step S700, the basic formula required is as follows:

[0097] U L =U LINK+ -U LINK -; among them, U L is the external terminal voltage;

[0098] U LINK+ =(V link+ -V REF )*(R1+R2) / R2+V REF Among them, U LINK+ is the voltage of the positive terminal of the load relative to the negative terminal of the battery; V link+ is the second link voltage; V REF is the output voltage of the reference circuit; R1 is the resistance value of the first voltage-dividing resistor R1, which is also the resistance value of the second voltage-dividing resistor R4; R2 is the resistance value of the second sampling resistor R2;

[0099] U LINK -=(V link --V REF )*(R1+R3) / R3+V REF Among them, U LINK - is the voltage of the negative end of the load relative to the negative end of the battery, V link- is the first link voltage; V REF is the output voltage of the reference circuit; R1 is the resistance value of the first voltage-dividing resistor R1, which is also the resistance value of the second voltage-dividing resistor R4; R3 is the resistance value of the first sampling resistor R3.

[0100] Combining the above three basic formulas, the formula for calculating the external terminal voltage in step S700 can be derived as follows:

[0101] U L =(V link+ -V REF )*(R1+R2) / R2-(V link --V REF )*(R1+R3) / R3.

[0102] Optionally, the relay adhesion voltage detection method further includes the following steps:

[0103] Step S800: If the first relay to be tested T1 is not adhered and the second relay to be tested T2 is adhered, the external terminal voltage is 0 V. In this embodiment, the external terminal voltage can be determined to be 0 V directly based on experience.

[0104] The third aspect of the present application provides a battery management system, including the above relay adhesion detection circuit. The third aspect of the present application discusses the above method from the perspective of detecting the external terminal voltage, taking into account the adhesion detection of T1 and T2. For details, please refer to Figure 1 and Figure 5 ; Figure 1 A module block diagram of a first embodiment of a relay adhesion detection circuit of the present invention; Figure 5 It is a flow chart of a first embodiment of a relay adhesion detection method applied in a battery management system of the present invention;

[0105] In this embodiment, U b is the battery voltage, i.e. the total input voltage of the relay sticking detection circuit; U L is the load voltage, i.e. the voltage at the external terminal of the relay adhesion detection; T1 is the total positive relay, i.e. the first relay to be tested; T2 is the total negative relay, i.e. the second relay to be tested; U LINK+ is the voltage of the positive end of the load relative to the negative end of the battery; U LINK - is the voltage of the negative end of the load relative to the negative end of the battery; GND inside the board is the negative end of the battery BAT-. AD channel is the analog sampling channel.

[0106] K1 is the switch on the sampling resistor bridge arm of the load positive end (LINK+). The voltage divider resistor on the bridge arm is R1, the sampling resistor is R2, and V link+is the sampling point on the bridge arm, i.e., the second link voltage; K2 is the relay on the bridge arm of the sampling resistor at the negative end of the load (LINK-), the voltage divider resistor on the bridge arm is R1, the sampling resistor is R3, V link - is the sampling point on the bridge arm, i.e., the first link voltage; V REF is the reference voltage, provided by the reference circuit; V L V link+ With V link- The differential sampling circuit outputs a signal. The resistance values ​​of the first voltage-dividing resistor R1 and the second voltage-dividing resistor R4 are both R1.

[0107] The specific method includes the following steps:

[0108] Step S11, close K2 and open K1, sample V link- ,

[0109] If V link- =V REF *R1 / (R1+R3), then T2 is adhered, otherwise T2 is not adhered;

[0110] Step S12, open K2, close K1, and sample V link+ , if V link+ =V REF , then T1 is not adhered;

[0111] Step S13: If it is determined according to steps S11 and S12 that T2 is not adhered and T1 is not adhered, then according to V L Calculate the external terminal voltage U L , there is formula 1 as follows:

[0112] Formula 1:

[0113] U L =(2*R1+R2+R3) / (R2+R3)*V L / A;

[0114] Step 14: If it is determined according to steps S11 and S12 that T2 is not adhered and T1 is adhered, the following formula is used to derive formula 2:

[0115] U L =U LINK+ -U LINK- ;

[0116] U LINK+ =(Vl ink+ -V REF )*(R1+R2) / R2+V REF ;

[0117] U LINK -=(V link --VREF )*(R1+R3) / R3+V REF ;

[0118] Formula 2:

[0119] U L =(V link+ -V REF )*(R1+R2) / R2-(V link- -V REF )*(R1+R3) / R3.

[0120] Step 15: If it is determined according to step S11 and step S12 that T2 is adhered and T1 is not adhered, UL=0;

[0121] Step S16: If T2 is determined to be adhered according to step S11, and V link+ >V REF , then according to V L Calculate the external terminal voltage U L , there is formula 3 as follows:

[0122] U L =(V L / AV REF +V link- )*(R1+R2) / R2+V REF ;

[0123] Step S17: Compare U L with U b , if U L =U b Then T1 is adhered, if U L ≠U b T1 is not adhered.

[0124] See also Figure 2 and Figure 6 , Figure 2 4 is a block diagram of a third embodiment of a relay adhesion detection circuit according to the present invention; Figure 6 The flowchart of the second embodiment of the relay adhesion detection method in the battery management system of the present invention is as follows. The third aspect of the present application focuses on detecting the external terminal voltage and takes the adhesion detection of T1 and T2 into consideration.

[0125] U b is the battery voltage, i.e. the total input voltage of the relay sticking detection circuit; U L is the load voltage, i.e. the voltage at the external terminal of the relay adhesion detection; T1 is the total positive relay, i.e. the first relay to be tested; T2 is the total negative relay, i.e. the second relay to be tested; U LINK+ is the voltage of the positive terminal of the load relative to the negative terminal of the battery, that is, the second link voltage; U LINK- is the voltage of the negative end of the load relative to the negative end of the battery; GND inside the board is the negative end of the battery BAT-. AD channel, that is, analog sampling channel. The resistance values ​​of the first voltage-dividing resistor R1 and the second voltage-dividing resistor R4 are both R1.

[0126] K1 is the switch on the sampling resistor bridge arm of the load positive end (LINK+). The voltage divider resistor on the bridge arm is R1, the sampling resistor is R2, and V link+ is the sampling point on the bridge arm, i.e., the second link voltage; K2 is the relay on the bridge arm of the sampling resistor at the negative end of the load (LINK-), the voltage divider resistor on the bridge arm is R1, the sampling resistor is R3, V link - is the sampling point on the bridge arm, i.e., the first link voltage; V REF is the reference voltage, provided by the reference circuit; V L V link+ With V link -The differential sampling circuit output signal.

[0127] Specifically, the following steps are included: Step S21, close K2 and disconnect K1, sample V link -, if V link - = V REF *R1 / (R1+R3), then T2 is adhered, otherwise T2 is not adhered;

[0128] Step S22, open K2, close K1, and sample V link+ , if V link+ =V REF , then T1 is not adhered;

[0129] Step S23: If it is determined according to steps S11 and S12 that T2 is not adhered and T1 is not adhered, then according to V L Calculate the external terminal voltage U L , there is formula 4 as follows:

[0130] U L =(R1+R2) / R2*V L / B-(V link- -V REF )*(R1+R3) / R3;

[0131] Step 24: If it is determined according to steps S21 and S22 that T2 is not adhered and T1 is adhered, the following formula is used to derive formula 5:

[0132] U L =U LINK+ -U LINK-

[0133] U LINK+ =(V link+ -V REF)*(R1+R2) / R2+V REF ;

[0134] U LINK- =(V link- -V REF )*(R1+R3) / R3+V REF ;

[0135] Formula 5:

[0136] U L =(V link+ -V REF )*(R1+R2) / R2-(V link- -V REF )*(R1+R3) / R3;

[0137] Step S25: If it is determined according to steps S21 and S22 that T2 is adhered and T1 is not adhered, then U L =0;

[0138] Step S26: If T2 is determined to be adhered according to step S21, and V link+ >V REF , then according to V L Calculate the external terminal voltage U L , apply Formula 6, as follows:

[0139] Formula 6:

[0140] U L =(R1+R2) / R2*V L / B+V REF ;

[0141] Step S27, compare U L with U b , if U L =U b , then T1 adhesion, if U L ≠U b , then T1 is not adhered.

[0142] The above embodiments in the third aspect of the present invention can all achieve the effect of detecting relay adhesion, and can also measure specific external terminal voltages under different adhesion states.

[0143] The above descriptions are merely embodiments of the present invention, and are not intended to limit the scope of the invention of this patent. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the protection scope of the present invention.

Claims

1. A relay adhesion detection circuit, comprising a first relay to be tested T1 connected in series between a positive terminal of a battery and one end of a load, and a second relay to be tested T2 connected in series between a negative terminal of the battery and the other end of the load, characterized in that: It also includes a first AD channel, a second AD channel, a reference circuit, a first voltage-dividing resistor R1, a second voltage-dividing resistor R4, a first sampling resistor R3, a first control switch K1, a second control switch K2, a second sampling resistor R2, a differential amplifier circuit and a third AD channel; One end of the first voltage-dividing resistor R1 is connected to a common connection point of the first relay T1 to be tested and the load, the other end of the first voltage-dividing resistor R1 is connected to one end of the first control switch K1, and the other end of the first control switch K1 is connected to an input end of the first AD channel; The output end of the reference circuit is connected to one end of the first sampling resistor R3, the other end of the first sampling resistor R3 is connected to one end of the second control switch K2, the other end of the second control switch K2 is connected to one end of the second voltage-dividing resistor R4, the other end of the second voltage-dividing resistor R4 is connected to the common connection point of the second relay to be tested T2 and the load; the other end of the first sampling resistor R3 is also connected to the input end of the second AD channel; The other end of the first control switch K1 is also connected to one end of the second sampling resistor R2, and the other end of the second sampling resistor R2 is also connected to one end of the first sampling resistor R3; The differential amplifier circuit includes a first differential amplifier input terminal, a second differential amplifier input terminal and a differential amplifier output terminal; the other end of the first control switch K1 is also connected to the first differential amplifier input terminal, the other end of the first sampling resistor R3 is connected to the second differential amplifier input terminal, and the differential amplifier output terminal is connected to the third AD channel; The relay sticking detection circuit is used to: disconnect the first control switch K1, close the second control switch K2, obtain the first link voltage and the output voltage of the reference circuit; wherein the first link voltage is the sampling voltage of the other end of the first sampling resistor R3; close the first control switch K1 and the second control switch K2 to obtain the output voltage of the reference circuit; determine whether the second relay to be tested T2 is stuck according to the first link voltage and the output voltage of the reference circuit; if the first relay to be tested T1 and the second relay to be tested T2 are not stuck, close the first control switch K1 and the second control switch K2 to obtain the output voltage of the differential amplifier circuit, the first link voltage and the second link voltage; wherein the second link voltage is the sampling voltage of the other end of the first control switch K1; calculate the external terminal voltage by using the output voltage of the differential amplifier circuit and the amplification factor of the differential amplifier circuit to the first link voltage and the second link voltage; and determine whether the first relay to be tested T1 is stuck by using the external terminal voltage and the voltage at both ends of the battery of the circuit. If the external terminal voltage is equal to the voltage at both ends of the battery of the circuit, the first relay to be tested T1 is stuck.

2. The relay adhesion detection circuit according to claim 1, characterized in that: It also includes a second sampling resistor R2, a differential amplifier circuit and a third AD channel, the other end of the first control switch K1 is also connected to one end of the second sampling resistor R2, and the other end of the second sampling resistor R2 is also connected to one end of the first sampling resistor R3; The differential amplifier circuit includes a first differential amplifier input terminal, a second differential amplifier input terminal and a differential amplifier output terminal; the other end of the first control switch K1 is also connected to the first differential amplifier input terminal, the output end of the reference circuit is connected to the second differential amplifier input terminal, and the differential amplifier output terminal is connected to the third AD channel.

3. A relay adhesion detection method, using the relay adhesion detection circuit as described in any one of claims 1 to 2, characterized in that: The steps include: Disconnect the first control switch K1, close the second control switch K2, and obtain the first link voltage and the output voltage of the reference circuit; wherein the first link voltage is the sampled voltage of the other end of the first sampling resistor R3; Closing the first control switch K1 and the second control switch K2 to obtain the output voltage of the reference circuit; Determining that the second relay to be tested T2 is adhered according to the first link voltage and the output voltage of the reference circuit; If the first relay to be tested T1 and the second relay to be tested T2 are not adhered, the first control switch K1 and the second control switch K2 are closed to obtain the output voltage of the differential amplifier circuit, the first link voltage and the second link voltage; wherein the second link voltage is a sampled voltage at the other end of the first control switch K1; Calculating an external terminal voltage by using the output voltage of the differential amplifier circuit and the amplification factor of the first link voltage and the second link voltage of the differential amplifier circuit; The external terminal voltage and the voltage across the battery of the circuit are used to determine whether the first relay to be tested T1 is stuck. If the external terminal voltage is equal to the voltage across the battery of the circuit, the first relay to be tested T1 is stuck.

4. The relay adhesion detection method according to claim 3, characterized in that: After determining that the second relay to be tested T2 is stuck, the method further includes the following steps: The first control switch K1 is closed, and the second control switch K2 is opened to obtain a second link voltage; wherein the second link voltage is a sampled voltage at the other end of the first control switch K1; Applying the second link voltage to compare with the output voltage of the reference circuit; If the second link voltage is greater than the output voltage of the reference circuit, the external terminal voltage is calculated by applying the second link voltage, the output voltage of the reference circuit, and the amplification factor of the first link voltage and the second link voltage by the differential amplifier circuit.

5. The relay adhesion detection method according to claim 3, characterized in that: The following steps are also included: Closing the first control switch K1 and opening the second control switch K2 to obtain the second link voltage; If the second link voltage is not equal to the output voltage of the reference circuit, the first relay T1 to be tested is stuck.

6. The relay adhesion detection method according to claim 4, characterized in that: If the first relay to be tested T1 is stuck and the second relay to be tested T2 is not stuck, the following steps are further included: The external terminal voltage is calculated by applying the first link voltage, the second link voltage, and the output voltage of the reference circuit.

7. The relay adhesion detection method according to claim 4, characterized in that: The following steps are also included: If the first relay to be tested T1 is not adhered and the second relay to be tested T2 is adhered, the external terminal voltage is 0V.

8. A battery management system, characterized in that: It comprises the relay adhesion detection circuit as described in any one of claims 1 to 2.

Images