Relay driving circuit, battery management system and electric vehicle

Abstract

The utility model relates to a relay driving circuit, a battery management system and an electric automobile, and the relay driving circuit comprises a driving circuit, a relay and a control circuit. Wherein the driving circuit is connected with the relay and the control circuit; the control circuit drives the relay to be closed through the driving circuit; in response to closing of the relay, enabling the driving circuit to discharge until discharging is completed so as to maintain closing of the relay; the normal state of the driving circuit is a charging state. According to the invention, the problems that the driving power consumption of the relay is high, the temperature rise of the coil is increased, and the requirement of high-power-density application is difficult to meet are solved, the driving power consumption of the relay is effectively reduced, the temperature rise of the coil is reduced, and thus the requirement of high-power-density application can be met.

Description

Technical Field

[0001] This utility model relates to the field of electronic technology, and in particular to a relay drive circuit, a battery management system, and an electric vehicle. Background Technology

[0002] With the development of electronic power technology in the new energy industry, the power density of products in related fields is increasing, which places higher demands on the application of relays, such as reducing size and power consumption. In existing technologies, in order to reduce the size of relays, the volume of the drive coil is usually reduced in the relay design. However, in order to obtain the same pull-in force, a smaller coil requires a larger current to achieve the relay closing operation. That is, when the coil internal resistance is lower, the drive power consumption is higher under the same drive voltage, resulting in higher drive power consumption of the relay and increased coil temperature rise, making it difficult to meet the needs of high power density applications.

[0003] There is currently no effective solution to the problem that the high power consumption of relays in related technologies leads to increased coil temperature rise, making it difficult to meet the requirements of high power density applications. Utility Model Content

[0004] Therefore, it is necessary to address the problem that the high power consumption of relays in the existing technology leads to increased coil temperature rise, making it difficult to meet the requirements of high power density applications, and to provide a relay drive circuit, a battery management system, and an electric vehicle.

[0005] In a first aspect, this utility model provides a relay driving circuit comprising: a driving circuit, a relay, and a control circuit; wherein the driving circuit is connected to the relay and the control circuit;

[0006] The control circuit drives the relay to close via the drive circuit;

[0007] In response to the closing of the relay, the drive circuit is discharged until the discharge is complete, so as to maintain the relay closed; the drive circuit is normally in a charging state.

[0008] In some embodiments, the driving circuit includes a charging / discharging unit, a switching unit, and a diode D1;

[0009] The switching unit is connected to the charging and discharging unit, the control circuit, and the power supply terminal;

[0010] The charging and discharging unit is connected to the diode D1 and the relay.

[0011] In some embodiments, the switching unit includes a diode D2, a resistor R1, a resistor R2, and a first switching transistor;

[0012] One end of the resistor R1 is connected to one end of the diode D1; the other end of the resistor R1 is connected to one end of the resistor R2 and the first switching transistor.

[0013] The other end of the resistor R2 is connected to the power supply terminal;

[0014] The other end of the diode D1 is connected to the control circuit and the relay.

[0015] In some of these embodiments, the first switching transistor is a transistor Q1;

[0016] The emitter of the transistor Q1 is connected to the power supply terminal;

[0017] The base of the transistor Q1 is connected to one end of the resistor R1;

[0018] The collector of the transistor Q1 is connected to the charging and discharging unit.

[0019] In some embodiments, the charging / discharging unit includes a capacitor C1 and a resistor R3;

[0020] The capacitor C1 is connected in parallel with the resistor R3.

[0021] In some embodiments, the drive circuit further includes a resistor R4;

[0022] One end of the resistor R4 is connected to the charging and discharging unit; the other end of the resistor R4 is grounded.

[0023] In some embodiments, the control circuit includes resistor R5, resistor R6, and a second switching transistor;

[0024] The resistor R5 is connected to the second switching transistor;

[0025] One end of the resistor R6 is connected to the second switching transistor; the other end of the resistor R6 is grounded and connected to the second switching transistor.

[0026] The second switching transistor is connected to the relay and the drive circuit.

[0027] In some embodiments, the second switching transistor is a field-effect transistor Q2;

[0028] The resistor R5 is connected to the gate of the field-effect transistor Q2;

[0029] One end of the resistor R6 is connected to the gate of the field-effect transistor Q2; the other end of the resistor R6 is grounded and connected to the source of the field-effect transistor Q2.

[0030] The drain of the field-effect transistor Q2 is connected to the relay and the drive circuit.

[0031] Secondly, this utility model provides a battery management system, the system including the relay drive circuit described in the first aspect above.

[0032] Thirdly, this utility model provides an electric vehicle, which includes the battery management system described in the second aspect above.

[0033] Compared with related technologies, the present invention provides a relay drive circuit, a battery management system, and an electric vehicle. The relay drive circuit includes a drive circuit, a relay, and a control circuit. The drive circuit is connected to the relay and the control circuit. The control circuit drives the relay to close via the drive circuit. In response to the relay closing, the drive circuit discharges until the discharge is complete, thus maintaining the relay closed. The drive circuit is normally in a charging state, solving the problem of high relay drive power consumption, which increases coil temperature and makes it difficult to meet the requirements of high power density applications. This invention effectively reduces relay drive power consumption and coil temperature rise, thereby meeting the needs of high power density applications.

[0034] Details of one or more embodiments of the present invention are set forth in the following drawings and description to make other features, objects and advantages of the present application more readily apparent. Attached Figure Description

[0035] Figure 1 This is a structural block diagram of a relay driving circuit provided in an embodiment of this application;

[0036] Figure 2 This is a schematic diagram of a driving circuit provided in an embodiment of this application;

[0037] Figure 3 This is a schematic diagram of a charging circuit provided in an embodiment of this application;

[0038] Figure 4 This is a schematic diagram of a control circuit provided in an embodiment of this application;

[0039] Figure 5 This is a schematic diagram of a relay drive circuit provided in a preferred embodiment of this application.

[0040] Reference numerals: 10, drive circuit; 11, charging and discharging unit; 12, switching unit; 20, relay; 30, control circuit. Detailed Implementation

[0041] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0042] It should be noted that when a component is said to be "installed on" another component, it can be directly on the other component or it may be in a component that is centered on it. When a component is said to be "set on" another component, it can be directly set on the other component or it may also be in a component that is centered on it. When a component is said to be "fixed to" another component, it can be directly fixed to the other component or it may also be in a component that is centered on it.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0044] This utility model provides a relay driving circuit. Figure 1 This is a structural block diagram of a relay drive circuit according to an embodiment of the present invention. Figure 1 As shown, the relay drive circuit includes: a drive circuit 10, a relay 20, and a control circuit 30; wherein, the drive circuit 10 is connected to the relay 20 and the control circuit 30.

[0045] The control circuit 30 drives the relay 20 to close via the drive circuit 10;

[0046] In response to the closing of relay 20, drive circuit 10 is discharged until the discharge is complete, so as to keep relay 20 closed; drive circuit 10 is normally in charging state.

[0047] In this embodiment, the relay driving circuit includes a driving circuit 10, a relay 20, and a control circuit 30. The driving circuit 10 is connected to the relay 20 and also to the control circuit 30. It should be noted that the driving circuit 10 is normally in a charging state. The control circuit 30 drives the relay 20 to close through the driving circuit 10. In response to the closing of the relay 20, the driving circuit 10 discharges until the discharge is complete, thereby maintaining the relay 20 closed.

[0048] Specifically, the drive circuit 10 includes a charging / discharging unit 11, which includes a capacitor C1 and a resistor R3 connected in parallel. When the control circuit 30 inputs an enable signal, the drive circuit 10 drives the relay 20 to close. In response to the closing of the relay 20, the charging / discharging unit 11 discharges until the discharge is complete, thereby maintaining the relay 20 closed. The drive circuit 10 may also include a switching unit 12 and a diode D1. The switching unit 12 includes a diode D2, resistors R1 and R2, and a first switching transistor. One end of resistor R1 is connected to one end of diode D1, and the other end of resistor R1 is connected to one end of resistor R2 and the first switching transistor. The other end of resistor R2 is connected to the power supply terminal (VCC). The other end of diode D1 is connected to the control circuit 30 and the relay 20. The charging / discharging unit 11 is connected to diode D1 and relay 20. The control circuit 30 includes resistor R5, resistor R6, and a second switching transistor. Resistor R5 is connected to the second switching transistor, one end of resistor R6 is connected to the second switching transistor, and the other end of resistor R6 is grounded and connected to the second switching transistor. The second switching transistor is connected to relay 20 and drive circuit 10.

[0049] When control circuit 30 receives an input enable signal (active high), it turns on the second switching transistor through resistors R5 and R6. At this time, resistors R2 and R1, along with diode D2, form a circuit through the second switching transistor, driving the first switching transistor to turn on. Subsequently, the power supply, the first switching transistor, capacitor C1, relay 20, and the second switching transistor form a drive circuit, driving relay 20 to close. At this point, diode D1 is reverse-biased and cut off. The voltage across the control coil of relay 20 is the sum of the power supply voltage and the voltage across capacitor C1, minus the voltage drop across the first and second switching transistors. The voltage setting for the control coil of relay 20 depends on the closing voltage required for relay 20 to close.

[0050] Furthermore, after relay 20 is activated, the discharge circuit containing capacitor C1 continues to discharge. The discharge time T1 is determined by a time constant composed of the total impedance of the relay 20 control coil internal resistance, the discharge circuit internal resistance, and the capacitance value of capacitor C1. The discharge circuit includes a power supply terminal, a first switching transistor, resistors R1 and R2, capacitor C1, resistor R3, relay 20, and a second switching transistor. It is understood that the capacitance value of capacitor C1 satisfies the minimum driving voltage sustaining time required for relay 20 to close, ensuring reliable closure of relay 20.

[0051] After a discharge period of time T1, capacitor C1 is fully discharged, and the voltage across capacitor C1 drops to the forward voltage drop of diode D1, causing diode D1 to conduct. At this time, the drive circuit of relay 20 becomes the power supply terminal, diode D1, relay 20, and the second switching transistor, and the drive voltage of the relay control coil is approximately the power supply terminal voltage.

[0052] With the development of electronic power technology in the new energy industry, the power density of products in related fields is increasing, which places higher demands on the application of relays, such as reducing size and power consumption. In existing technologies, in order to reduce the size of relays, the volume of the drive coil is usually reduced in the relay design. However, in order to obtain the same pull-in force, a smaller coil requires a larger current to achieve the relay closing operation. That is, when the coil internal resistance is lower, the drive power consumption is higher under the same drive voltage, resulting in higher drive power consumption of the relay and increased coil temperature rise, making it difficult to meet the needs of high power density applications.

[0053] Compared to existing technologies, this application presents a relay drive circuit comprising a drive circuit, a relay, and a control circuit. The drive circuit is connected to both the relay and the control circuit. The control circuit drives the relay to close via the drive circuit. In response to the relay closing, the drive circuit discharges until the discharge is complete, maintaining the relay's closure. The drive circuit is normally in a charging state. Based on this, by connecting the drive circuit, which is normally in a charging state, to the relay and the control circuit, and then discharging the drive circuit after it drives the relay to close, energy is consumed through charging and discharging to reduce power consumption. This solves the problem of high relay drive power consumption, which increases coil temperature and makes it difficult to meet the requirements of high power density applications. It effectively reduces relay drive power consumption and coil temperature rise, thus meeting the needs of high power density applications.

[0054] In some of these embodiments, such as Figure 2 As shown, the driving circuit 10 includes a charging / discharging unit 11, a switching unit 12, and a diode D1;

[0055] The switching unit 12 is connected to the charging / discharging unit 11, the control circuit 30, and the power supply terminal.

[0056] The charging and discharging unit 11 is connected to diode D1 and relay 20.

[0057] In this embodiment, the driving circuit 10 includes a charging and discharging unit 11, a switching unit 12, and a diode D1. The switching unit 12 is connected to the charging and discharging unit 11, the control circuit 30, and the power supply terminal. The charging and discharging unit 11 includes a capacitor C1 and a resistor R3 connected in parallel. The charging and discharging unit 11 is connected to the diode D1 and the relay 20.

[0058] Specifically, when the control circuit 30 receives an enable signal, the second switching transistor is turned on through resistors R5 and R6, causing the switching unit 12 to conduct and drive the relay 20 to close. At this time, diode D1 is reverse-biased and cut off. After the relay 20 is effectively driven, the discharge circuit containing capacitor C1 continues to discharge until capacitor C1 is completely discharged. The voltage of capacitor C1 drops to the forward voltage drop of diode D1, causing diode D1 to conduct. The driving circuit of relay 20 then becomes the power supply terminal, diode D1, relay 20, and the second switching transistor.

[0059] In this embodiment, the driving circuit 10 includes a charging / discharging unit 11, a switching unit 12, and a diode D1. The switching unit 12 is connected to the charging / discharging unit 11, the control circuit 30, and the power supply. The charging / discharging unit 11 is connected to the diode D1 and the relay 20. Thus, by controlling the switching unit 12 to conduct, a driving circuit for the relay 20 is formed, thereby driving the relay 20 to close effectively.

[0060] In some embodiments, the switching unit 12 includes a diode D2, a resistor R1, a resistor R2, and a first switching transistor;

[0061] One end of resistor R1 is connected to one end of diode D1; the other end of resistor R1 is connected to one end of resistor R2 and the first switching transistor.

[0062] The other end of resistor R2 is connected to the power supply terminal;

[0063] The other end of diode D1 is connected to control circuit 30 and relay 20.

[0064] In this embodiment, the switching unit 12 includes a diode D2, a resistor R1, a resistor R2, and a first switching transistor. One end of resistor R1 is connected to one end of diode D1, the other end of resistor R1 is connected to one end of resistor R2 and the first switching transistor, the other end of resistor R2 is connected to the power supply terminal, and the other end of diode D1 is connected to the control circuit 30 and the relay 20. The first switching transistor can be a transistor, a field-effect transistor, etc., and is not limited thereto.

[0065] Specifically, when control circuit 30 is turned on, resistors R2 and R1, and diode D2 form a circuit through the second switching transistor, driving the first switching transistor to turn on. The power supply terminal, the first switching transistor, capacitor C1, relay 20, and the second switching transistor form a driving circuit, driving relay 20 to close. At this time, diode D1 is reverse-biased and cut off. After relay 20 is effectively driven, the discharge circuit containing capacitor C1 continues to discharge until capacitor C1 is completely discharged, causing diode D1 to turn on. The discharge circuit includes the power supply terminal, the first switching transistor, resistors R1 and R2, capacitor C1, resistor R3, relay 20, and the second switching transistor. After the discharge is complete, the driving circuit of relay 20 becomes the power supply terminal, diode D1, relay 20, and the second switching transistor. The driving voltage of the relay control coil is approximately the power supply terminal voltage.

[0066] Preferably, the first switching transistor is a transistor Q1. The emitter of transistor Q1 is connected to the power supply terminal, the base of transistor Q1 is connected to one end of resistor R1, and the collector of transistor Q1 is connected to the charging / discharging unit 11. When resistor R2, resistor R1, and diode D2 form a circuit through the second switching transistor, transistor Q1 is driven to conduct.

[0067] In this embodiment, a switching unit 12 is formed by diode D2, resistor R1, resistor R2 and first switching transistor. When the control circuit 30 is turned on, a circuit is formed by diode D2, resistor R1 and resistor R2 to drive the first switching transistor to turn on.

[0068] In some embodiments, the charging / discharging unit 11 includes a capacitor C1 and a resistor R3;

[0069] Capacitor C1 is connected in parallel with resistor R3.

[0070] Specifically, the charging / discharging unit 11 includes a capacitor C1 and a resistor R3, which are connected in parallel. Under normal conditions, the charging / discharging unit 11 is in a charging state. When the control circuit 30 is turned on, the first switching transistor of the driving circuit 10 is turned on, and the power supply terminal, the first switching transistor, the capacitor C1, the relay 20, and the second switching transistor form a driving circuit to drive the relay 20 to close. At this time, the diode D1 is reverse-biased and cut off, and the voltage of the relay control coil is the sum of the power supply terminal voltage and the voltage of the capacitor C1 minus the voltage drop across the first and second switching transistors.

[0071] After relay 20 is activated, capacitor C1 continues to discharge until it is fully discharged. The voltage across capacitor C1 drops to the forward voltage drop of diode D1, causing diode D1 to conduct. The drive circuit for relay 20 then becomes the power supply terminal, diode D1, relay 20, and the second switching transistor. Taking an open-circuit resistor R3 as an example, the relay power consumption is explained as follows: Relay 20 is closed by drive circuit 10 with a coil drive voltage approximately twice the power supply terminal voltage. When capacitor C1 is fully discharged, diode D1, which has a negative voltage, conducts. At this point, the coil drive voltage of relay 20 drops to approximately the power supply terminal voltage. Therefore, for the same relay control coil, the final drive power consumption is significantly lower than the closing drive power. This effectively reduces the drive loss of relay 20 and optimizes its heat generation while ensuring reliable closure of relay 20.

[0072] It should be noted that the discharge circuit includes a power supply terminal, a first switching transistor, resistors R1 and R2, capacitor C1, resistor R3, relay 20, and a second switching transistor. The continuous discharge time is determined by the time constant composed of the total impedance of the relay control coil internal resistance, the discharge circuit internal resistance, and the capacitance value of capacitor C1. The capacitance value of capacitor C1 satisfies the minimum driving voltage maintenance time for relay 20 to close, so as to ensure that relay 20 closes reliably.

[0073] In this embodiment, the parallel capacitor C1 and resistor R3 are used as the charging and discharging unit 11, forming a charging circuit with the power supply terminal and diode D1. This keeps the drive circuit 10 in a charging state under normal conditions and discharges in response to the closing of the relay 20, forming another drive circuit to maintain the relay 20 closed, thereby reducing the driving power consumption of the relay 20 and reducing the coil temperature rise.

[0074] In some embodiments, the drive circuit 10 further includes a resistor R4;

[0075] One end of resistor R4 is connected to the charging / discharging unit 11; the other end of resistor R4 is grounded.

[0076] Specifically, the drive circuit 10 includes resistor R4. For example... Figure 3 As shown, for the normal driving circuit 10, a charging circuit is formed by the power supply terminal, diode D1, capacitor C1, resistor R3, and resistor R4. The power supply terminal charges capacitor C1 through diode D1, capacitor C1, resistor R3, and resistor R4. The charging voltage of capacitor C1 is determined by the voltage division between resistors R3 and R4. For example, when resistor R3 is open, the charging voltage of capacitor C1 is the voltage division value of R3.

[0077] In this embodiment, the driving circuit 10 is in a charging state under normal conditions through a charging circuit formed by the power supply terminal, diode D1, capacitor C1, resistor R3 and resistor R4.

[0078] In some of these embodiments, such as Figure 4 As shown, the control circuit 30 includes resistor R5, resistor R6, and a second switching transistor.

[0079] Resistor R5 is connected to the second switching transistor;

[0080] One end of resistor R6 is connected to the second switching transistor; the other end of resistor R6 is grounded and connected to the second switching transistor.

[0081] The second switching transistor is connected to the relay 20 and the drive circuit 10.

[0082] Specifically, the control circuit 30 includes resistors R5 and R6, and a second switching transistor. Resistor R5 is connected to the second switching transistor, one end of resistor R6 is connected to the second switching transistor, and the other end of resistor R6 is grounded and connected to the second switching transistor. The second switching transistor is connected to the relay 20 and the drive circuit 10. When an enable signal is input to the control circuit 30, the second switching transistor is turned on through resistors R5 and R6. In this embodiment, the second switching transistor can be a field-effect transistor, a bipolar transistor, etc.

[0083] Preferably, the second switching transistor is a field-effect transistor Q2. Resistor R5 is connected to the gate of field-effect transistor Q2, one end of resistor R6 is connected to the gate of field-effect transistor Q2, the other end of resistor R6 is grounded and connected to the source of field-effect transistor Q2, and the drain of field-effect transistor Q2 is connected to relay 20 and drive circuit 10.

[0084] In this embodiment, the control circuit 30 is connected to the drive circuit 10 and the relay 20. The control circuit 30 includes resistors R5 and R6 and a second switching transistor, so that when an enable signal is input, the second switching transistor is turned on to control the operation of the drive circuit 10.

[0085] The present embodiment will now be described and illustrated through preferred embodiments.

[0086] Figure 5 This is a schematic diagram of a relay drive circuit provided in a preferred embodiment of this application, as shown below. Figure 5 As shown, the relay driving circuit includes: a driving circuit 10, a control circuit 30, and a relay 20; wherein, the driving circuit 10 includes a diode D2, a resistor R1, a resistor R2, a transistor Q1, a capacitor C1, a resistor R3, a resistor R4, and a diode D1; the control circuit 30 includes a resistor R5, a resistor R6, and a field-effect transistor Q2.

[0087] In this embodiment, resistor R5 is connected to field-effect transistor Q2, one end of resistor R6 is connected to the second switching transistor, and the other end of resistor R6 is connected to field-effect transistor Q2 and grounded. Field-effect transistor Q2 is connected to relay 20 and drive circuit 10. When the control circuit 30 inputs an enable signal, it turns on the second switching transistor through resistors R5 and R6. At this time, resistors R2 and R1 and diode D2 form a circuit through the second switching transistor, driving the first switching transistor to turn on. Then, as... Figure 5 As shown, the power supply terminal, transistor Q1, capacitor C1, relay 20 and field-effect transistor Q2 form a driving circuit, driving relay 20 to close, and diode D1 to be reverse-biased and cut off. The voltage of the relay control coil is the sum of the power supply terminal voltage and the capacitor C1 voltage minus the voltage drop of transistor Q1 and field-effect transistor Q2.

[0088] Furthermore, after relay 20 is effectively driven, a discharge circuit is formed, including the power supply terminal, transistor Q1, resistors R1 and R2, capacitor C1, resistor R3, relay 20, and field-effect transistor Q2. The discharge circuit containing capacitor C1 continues to discharge, and the discharge time T1 is determined by the time constant composed of the internal resistance of the relay control coil, the total impedance of the discharge circuit, and the capacitance value of capacitor C1. After discharge for time T1, capacitor C1 is fully discharged, and the voltage of capacitor C1 drops to the forward voltage drop of diode D1, causing diode D1 to conduct. At this time, the driving circuit of relay 20 becomes the power supply terminal, diode D1, relay 20, and field-effect transistor Q2, and the driving voltage of the relay control coil is approximately the power supply terminal voltage.

[0089] In this embodiment, the drive circuit 10 is connected to the relay 20 and the control circuit 30. The drive circuit 10 is normally in a charging state. After the control drive circuit 10 drives the relay 20 to close, the drive circuit 10 discharges until the discharge is complete. Then, the diode D1 turns on, making the drive circuit the power supply terminal, diode D1, relay 20 and field-effect transistor Q2. In this way, energy is consumed through charging and discharging to reduce power consumption. This solves the problem that the drive power consumption of the relay 20 is high, which increases the coil temperature rise and makes it difficult to meet the requirements of high power density applications. It effectively reduces the drive power consumption of the relay 20 and reduces the coil temperature rise, thereby meeting the requirements of high power density applications.

[0090] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0091] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A relay drive circuit, characterized in that, The relay driving circuit includes: a driving circuit, a relay, and a control circuit; wherein the driving circuit is connected to the relay and the control circuit. The control circuit drives the relay to close via the drive circuit; In response to the closing of the relay, the drive circuit is discharged until the discharge is complete, so as to maintain the relay closed; the drive circuit is normally in a charging state.

2. The relay drive circuit according to claim 1, characterized in that, The driving circuit includes a charging and discharging unit, a switching unit, and a diode D1; The switching unit is connected to the charging and discharging unit, the control circuit, and the power supply terminal; The charging and discharging unit is connected to the diode D1 and the relay.

3. The relay drive circuit according to claim 2, characterized in that, The switching unit includes a diode D2, a resistor R1, a resistor R2, and a first switching transistor; One end of the resistor R1 is connected to one end of the diode D1; the other end of the resistor R1 is connected to one end of the resistor R2 and the first switching transistor. The other end of the resistor R2 is connected to the power supply terminal; The other end of the diode D1 is connected to the control circuit and the relay.

4. The relay drive circuit according to claim 3, characterized in that, The first switching transistor is transistor Q1; The emitter of the transistor Q1 is connected to the power supply terminal; The base of the transistor Q1 is connected to one end of the resistor R1; The collector of the transistor Q1 is connected to the charging and discharging unit.

5. The relay drive circuit according to claim 2, characterized in that, The charging and discharging unit includes a capacitor C1 and a resistor R3; The capacitor C1 is connected in parallel with the resistor R3.

6. The relay drive circuit according to claim 2, characterized in that, The driving circuit also includes a resistor R4; One end of the resistor R4 is connected to the charging and discharging unit; the other end of the resistor R4 is grounded.

7. The relay drive circuit according to claim 1, characterized in that, The control circuit includes resistor R5, resistor R6, and a second switching transistor. The resistor R5 is connected to the second switching transistor; One end of the resistor R6 is connected to the second switching transistor; the other end of the resistor R6 is grounded and connected to the second switching transistor. The second switching transistor is connected to the relay and the drive circuit.

8. The relay drive circuit according to claim 7, characterized in that, The second switching transistor is a field-effect transistor Q2; The resistor R5 is connected to the gate of the field-effect transistor Q2; One end of the resistor R6 is connected to the gate of the field-effect transistor Q2; the other end of the resistor R6 is grounded and connected to the source of the field-effect transistor Q2. The drain of the field-effect transistor Q2 is connected to the relay and the drive circuit.

9. A battery management system, characterized in that, The system includes a relay and a relay drive circuit as claimed in any one of claims 1 to 8.

10. An electric vehicle, characterized in that, The electric vehicle includes the battery management system as described in claim 9.

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