Charge and discharge current identification circuit and lithium battery

Abstract

The utility model provides a charging and discharging current identification circuit and a lithium battery, the circuit comprises a main loop current detection resistor, a discharging circuit and a charging circuit, the discharging circuit comprises a first field effect transistor, a second field effect transistor, a first resistor and a second resistor, the charging sub-circuit comprises a third field effect transistor, a fourth field effect transistor, a third resistor, a fourth resistor and a charging loop current detection resistor, the two ends of the charging loop current detection resistor are connected with the two collecting ends of the charging loop current collector respectively, and the first end of the charging loop current detection resistor is connected with the second end of the main loop current detection resistor. When the charging loop current collector detects that the current passes through the charging loop current detection resistor, the MCU identifies the current as the charging current; when the vehicle is braked during riding, the charging loop current collector detects that the charging loop current detection resistor has no current, and then the MCU identifies the current as feedback current. Therefore, the circuit can accurately identify the charging current or the feedback current, so that the charging protection parameters are accurately set, and the normal use of the whole vehicle is ensured.

Description

Technical Field

[0001] The present disclosure relates to a technical field, and in particular to a charge and discharge current identification circuit and a lithium battery. Background Art

[0002] With the continuous development of lithium batteries for electric vehicles, when the lithium battery is discharged, when the vehicle is braking, the braking energy will be recovered, and a charging current (this current is the current generated when the vehicle is braking, also known as feedback current) will be input from the discharge port P-end of the battery. In the existing technical design, Figure 1 As shown, the common circuit is provided with a main circuit current sensing resistor, and the main circuit current sensing resistor is connected to the main circuit current sampling device 110 (such as Figure 2 As shown in the figure, it is possible to determine whether it is a charging current or a discharging current by using the overcurrent protection parameter. However, it is impossible to distinguish whether the current is a charging current of a charging circuit or a feedback current of a discharging circuit (the feedback current is also a charging current for the battery collection module). In this way, the charging overcurrent protection parameter may be predicted due to the feedback current or the protection parameter may be set too large, resulting in a weakened protection capability.

[0003] Similarly, the prior art CN107179511A discloses a circuit structure and method for detecting charge and discharge currents, the structure comprising: a closed-loop Hall sensor, a voltage circuit and an operational amplifier circuit; the closed-loop Hall sensor is mounted on the positive bus of the battery pack of the electric vehicle battery management system, and is used to sense the current on the bus and output a voltage signal; the voltage circuit is connected to the input end of the operational amplifier circuit, and is used to provide a lift voltage Vref; and is used to superimpose the voltage signal output by the closed-loop Hall sensor and the lift voltage Vref, thereby outputting a positive voltage signal to the AD port of the single-chip microcomputer. The detection circuit realizes the acquisition of the positive and negative voltage signals output by the closed-loop Hall sensor by the AD port of the single-chip microcomputer through a first-level operational amplifier circuit, thereby making an accurate judgment on the direction and magnitude of the current flowing through the positive bus of the battery pack.

[0004] However, when applied to a vehicle, when the vehicle is in a state of braking energy recovery, current flows through, and the circuit structure cannot identify whether the current is a charging current of a charging circuit or a feedback current of a discharging circuit.

[0005] The two existing technologies may easily cause abnormalities due to situations that cannot be judged. For example, if the feedback current is greater than the battery charging overcurrent protection parameter, a charging error display will be generated, causing the entire vehicle to issue an error warning, making consumers think that there is a problem with the vehicle. Utility Model Content

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a charge and discharge current identification circuit and a lithium battery that can effectively identify the charging current and the feedback current.

[0007] The purpose of this disclosure is achieved through the following technical solutions:

[0008] A charge and discharge current identification circuit comprises a main circuit current detection resistor, a discharge subcircuit and a charge subcircuit, wherein the discharge subcircuit comprises a first field effect tube, a second field effect tube, a first resistor and a second resistor, the two ends of the main circuit current detection resistor are respectively connected to the two collection ends of the main circuit current collector, the first end of the main circuit current detection resistor is grounded, the second end of the main circuit current detection resistor is respectively connected to the source and the discharge signal end of the first field effect tube, the drain of the first field effect tube is connected to the drain of the second field effect tube, the gate of the first field effect tube is connected to the discharge signal end through the first resistor, the source of the second field effect tube is connected to the discharge cathode, and the gate of the second field effect tube is connected to the discharge cathode through the second resistor. The charging subcircuit comprises a third field effect tube, a fourth field effect tube, a third resistor, a fourth resistor and a charging circuit current detection resistor, the two ends of the charging circuit current detection resistor are respectively connected to the two collection ends of the charging circuit current collector, the first end of the charging circuit current detection resistor is connected to the second end of the main circuit current detection resistor, the second end of the charging circuit current detection resistor is connected to the drain of the third field effect tube, the source of the third field effect tube is connected to the source of the fourth field effect tube, the gate of the third field effect tube is connected to the charging signal end through the third resistor, the drain of the fourth field effect tube is connected to the charging negative electrode, and the gate of the fourth field effect tube is connected to the gate signal driving end 2 through the fourth resistor.

[0009] In one embodiment, the discharge subcircuit further includes a fifth field effect transistor and a fifth resistor, the source of the fifth field effect transistor is connected to the second end of the main loop current sensing resistor, the drain of the fifth field effect transistor is connected to the drain of the second field effect transistor, and the gate of the fifth field effect transistor is connected to the discharge signal terminal through the fifth resistor.

[0010] In one embodiment, the discharge subcircuit further includes a sixth field effect transistor and a sixth resistor, the drain of the sixth field effect transistor is connected to the drain of the fifth field effect transistor, the source of the sixth field effect transistor is connected to the discharge cathode, and the gate of the sixth field effect transistor is connected to the gate signal drive 1 terminal through the sixth resistor.

[0011] In one embodiment, the discharge subcircuit further includes a filter resistor and a filter capacitor connected in parallel, the first resistor and the fifth resistor are both connected to the discharge signal end through the filter resistor, the upper end of the filter capacitor is connected to the first end of the filter resistor, and the lower end of the filter capacitor is connected to the second end of the filter resistor.

[0012] In one embodiment, the discharge subcircuit further includes a stabilizing diode, an anode of the stabilizing diode is connected to the second end of the main loop current sensing resistor, a cathode of the stabilizing diode is connected to the first end of the first resistor, and a second end of the first resistor is connected to the gate of the first field effect transistor.

[0013] In one embodiment, the charging sub-circuit further includes a seventh field effect transistor and a seventh resistor, the drain of the seventh field effect transistor is connected to the second end of the charging loop current sensing resistor, the source of the seventh field effect transistor is connected to the source of the fourth field effect transistor, and the gate of the seventh field effect transistor is connected to the charging signal end through the seventh resistor.

[0014] In one embodiment, the charging sub-circuit also includes an eighth field effect transistor and an eighth resistor, the source of the eighth field effect transistor is connected to the source of the seventh field effect transistor, the drain of the eighth field effect transistor is connected to the charging negative electrode, and the gate of the eighth field effect transistor is connected to the gate signal drive 2 terminal through the eighth resistor.

[0015] In one embodiment, the charging sub-circuit further includes a fuse resistor, and the drain of the fourth field effect transistor and the drain of the eighth field effect transistor are both connected to the charging negative electrode through the fuse resistor.

[0016] A lithium battery comprises the charge and discharge current identification circuit described in any one of the above embodiments.

[0017] Compared with the prior art, the present invention has at least the following advantages:

[0018] The charging and discharging current identification circuit sets a charging circuit current detection resistor in the charging subcircuit, which is detected by the charging circuit current sampler. When the vehicle is charging, the main circuit current sampler detects that there is current passing through the main circuit current detection resistor, and the charging circuit current sampler detects that there is current passing through the charging circuit current detection resistor, so the MCU identifies it as charging current; when the vehicle is riding and braking, the main circuit current sampler detects that there is current passing through the main circuit current detection resistor, and the charging circuit current sampler detects that there is no current in the charging circuit current detection resistor, and then the MCU identifies it as feedback current. In this way, it can accurately identify whether it is the charging current of the charging circuit or the feedback current of the discharging circuit, so that the charging protection parameters are accurately set, and there is no misjudgment or the protection range is increased, which leads to a weakening of the protection capability, ensuring the normal use of the whole vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A circuit diagram of a charge and discharge current identification circuit in the prior art;

[0021] Figure 2 It is a circuit diagram of a main circuit current collector in the prior art;

[0022] Figure 3 is a circuit diagram of a charge and discharge current identification circuit in one embodiment;

[0023] Figure 4 for Figure 3 The circuit diagram of the discharge sub-circuit in the charge and discharge current identification circuit shown;

[0024] Figure 5 for Figure 3 A circuit diagram of a charging subcircuit in the charging and discharging current identification circuit shown;

[0025] Figure 6 FIG. 4 is a circuit diagram of a charging circuit current sampler in one embodiment. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are given in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thoroughly and comprehensively understood.

[0027] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0029] In order to better understand the technical solutions and beneficial effects of the present invention, the present invention is further described in detail below in conjunction with specific embodiments:

[0030] like Figures 3 to 5As shown, a charge and discharge current identification circuit 10 of an embodiment includes a main circuit current detection resistor RG1, a discharge subcircuit 100 and a charging subcircuit 200. The discharge subcircuit 100 includes a first field effect transistor M1, a second field effect transistor M2, a first resistor R1 and a second resistor R2. The two ends of the main circuit current detection resistor RG1 are respectively connected to the main circuit current sampling device 110 ( Figure 2 ) two collection ends, specifically GND1 end and DS1 end, the first end of the main loop current detection resistor RG1 is grounded, the second end of the main loop current detection resistor RG1 is respectively connected to the source of the first field effect tube M1 and the discharge signal end GD2, the drain of the first field effect tube M1 is connected to the drain of the second field effect tube M2, the gate of the first field effect tube M1 is connected to the discharge signal end GD2 through the first resistor R1, the source of the second field effect tube M2 is connected to the discharge negative electrode, the gate of the second field effect tube M2 is connected to the gate signal drive 1 end GC2 through the second resistor R2, further, the gate of the second field effect tube M2 is connected to the drive port GC2 of the MOS drive chip through the second resistor R2; the charging sub-circuit 200 includes a third field effect tube M3, a fourth field effect tube M4, a third resistor R3, a fourth resistor R4 and a charging loop current detection resistor RG2, and the two ends of the charging loop current detection resistor RG2 are respectively connected to the charging loop current collector 210( Figure 6 ), specifically, the DS1 terminal and the CDS1 terminal, the first terminal of the charging loop current-sensing resistor RG2 is connected to the second terminal of the main loop current-sensing resistor RG1, the second terminal of the charging loop current-sensing resistor RG2 is connected to the drain of the third field effect transistor M3, the source of the third field effect transistor M3 is connected to the source of the fourth field effect transistor M4, the gate of the third field effect transistor M3 is connected to the charging signal terminal GC through the third resistor R3, the drain of the fourth field effect transistor M4 is connected to the charging negative electrode, the gate of the fourth field effect transistor M4 is connected to the gate signal driving 2 terminal GB through the fourth resistor R4, and further, the gate of the fourth field effect transistor M4 is connected to the driving port GB of the MOS driving chip through the fourth resistor R4.

[0031] The main circuit current collector 110 is used to collect the charging current or discharging current passing through the main circuit current sensing resistor RG1, and the charging circuit current collector 210 is used to collect the current of the charging circuit current sensing resistor RG2. When the battery is charging, current passes through both the main circuit current sensing resistor RG1 and the charging circuit current sensing resistor RG2, and the control unit (MCU) determines it as charging current; when the battery is used and the vehicle is braked, current passes through the main circuit current sensing resistor RG1 and no current passes through the charging circuit current sensing resistor RG2, and the MCU determines it as feedback current.

[0032] Furthermore, the first field effect transistor M1 is a discharge MOS transistor, the second field effect transistor M2 is a blocking charge MOS transistor, the third field effect transistor M3 is a charge MOS transistor, and the fourth field effect transistor M4 is a blocking discharge MOS transistor, and the above MOS transistors are all NMOS transistors.

[0033] In order to facilitate relevant technical personnel to understand the technology of the present disclosure, Figures 2 to 6 The following two implementations are described:

[0034] Embodiment 1: When the charger is input at the charging port, the battery is charged. At this time, the current passes through the main circuit current sensing resistor RG1 and the charging sub-circuit 200 in sequence, the first field effect transistor M1 is turned off, and the drain of the second field effect transistor M2 is turned off because no current passes through it. A signal at the charging signal terminal GC passes through the gate of the third field effect transistor M3, thereby turning on the third field effect transistor M3. After the current passes through the source of the fourth field effect transistor M4, a signal at the gate signal driving terminal GB passes through the gate of the fourth field effect transistor M4, making its gate voltage greater than the source voltage, thereby turning it on and preventing the battery from discharging. At this time, the current passes through the DS1 terminal and the GND1 terminal of the main circuit current sampler 110 respectively, and the information is input to the chip U1 of the main circuit current sampler 110. After the main circuit current sampler 110 collects the current, it is fed back to the control unit (MCU) through the output terminals D_ADC and C_ADC, and then the MCU controls the charging circuit current sampler 210. At this time, the current passes through the DS1 terminal and the CDS1 terminal of the charging circuit current sampler 210 respectively, and the information is input to the chip U2 of the charging circuit current sampler 210. After collecting the charging current of the charging circuit current detection resistor RG2, it is fed back to the MCU through the output terminals C_D_ADC and C_C_ADC, and then the MCU recognizes the current as the charging current. Furthermore, if the current is too large during the subsequent charging process, the MCU can normally perform overcurrent protection.

[0035] Embodiment 2: When the electric vehicle is running, the battery is discharged. At this time, the main circuit current sensing resistor RG1 has a discharge current passing through it. The main circuit current sampling device 110 detects that there is a current passing through the main circuit current sensing resistor RG1. The MCU determines that it is a discharge current. When the electric vehicle brakes, the battery is charged from the discharge port negative electrode P-. At this time, the third field effect transistor M3 has no current and is turned off. The fourth field effect transistor M4 has no current passing through it and is also turned off. In the first field effect transistor M1, the discharge signal terminal GD has a signal passing through its gate to turn on the first field effect transistor M1, and the second field effect transistor M2 is turned on to prevent the battery from charging. At this time, the main circuit current sampling device 110 detects that there is a charging current passing through it and feeds back the information to the control unit (MCU). The MCU then controls the charging circuit current sampling device 210. The charging circuit current sampling device 210 detects that there is no charging current in the charging circuit current sensing resistor RG2. Then, the MCU identifies the current as a feedback current. This current will not be included in the charging current, and there is no need for overcurrent protection.

[0036] In addition, a first voltage-stabilizing resistor RZ1 and a first voltage-stabilizing diode DZ1 are arranged between the gate and the source of the first field effect transistor M1. The first voltage-stabilizing resistor RZ1 is connected in parallel with the first voltage-stabilizing diode DZ1, wherein the anode of the first voltage-stabilizing diode DZ1 is connected to the source of the first field effect transistor M1, and the cathode of the first voltage-stabilizing diode DZ1 is connected to the gate of the first field effect transistor M1, so as to protect the gate and source of the first field effect transistor M1, and prevent the current from being too large and the gate from being suspended and then burned. This connection plays a role in voltage stabilization. A second voltage-stabilizing resistor RZ2 and a second voltage-stabilizing diode DZ2 connected in parallel are arranged between the gate and the source of M2 to protect the gate and the source of the second field effect transistor M2; a third voltage-stabilizing resistor RZ3 and a third voltage-stabilizing diode DZ3 are arranged between the gate and the source of the third field effect transistor M3 to protect the gate and the source of the third field effect transistor M3; a fourth voltage-stabilizing resistor RZ4 and a fourth voltage-stabilizing diode DZ4 are arranged between the gate and the source of the fourth field effect transistor M4 to protect the gate and the source of the fourth field effect transistor M4.

[0037] like Figure 4 As shown, in one embodiment, the discharge sub-circuit 100 further includes a fifth field effect transistor M5 and a fifth resistor R5, the source of the fifth field effect transistor M5 is connected to the second end of the main loop current detection resistor RG1, the drain of the fifth field effect transistor M5 is connected to the drain of the second field effect transistor M2, and the gate of the fifth field effect transistor M5 is connected to the discharge signal terminal GD2 through the fifth resistor R5. In this embodiment, the fifth field effect transistor M5 is a discharge MOS tube. When the battery is discharged, the discharge sub-circuit 100 is powered on, and a signal passes through the gate of the fifth field effect transistor M5 at the discharge signal terminal GD, and the fifth field effect transistor M5 is turned on, and the first field effect transistor M1 is turned on at the same time.

[0038] Furthermore, a fifth voltage-stabilizing resistor RZ5 and a fifth voltage-stabilizing diode DZ5 connected in parallel are provided between the gate of the fifth field effect transistor M5 and its source, and the connection relationship and effect thereof are the same as the connection relationship and effect of the first voltage-stabilizing resistor RZ1 and the first voltage-stabilizing diode DZ1. It should be noted that the first field effect transistor M1 and the fifth field effect transistor M5 are connected in parallel to form a discharge MOS tube. In an actual circuit, the number of discharge MOS tubes is not limited to that in the current circuit diagram, and a plurality of field effect transistors are connected in parallel to form a discharge MOS tube, and the current circuit diagram is used as a simple illustration.

[0039] like Figure 4As shown, in one embodiment, the discharge sub-circuit 100 further includes a sixth field effect transistor M6 and a sixth resistor R6, the drain of the sixth field effect transistor M6 is connected to the drain of the fifth field effect transistor M5, the source of the sixth field effect transistor M6 is connected to the discharge cathode, and the gate of the sixth field effect transistor M6 is connected to the gate signal driving terminal 1 GC2 through the sixth resistor R6. In this embodiment, the sixth field effect transistor M6 is a blocking charging MOS tube, when the battery is discharged, the discharge sub-circuit 100 is powered on, and the gate signal driving terminal 1 GC2 has a signal passing through the gate of the sixth field effect transistor M6, and then turned on, so as to prevent the discharge sub-circuit 100 from charging, and at the same time, the second field effect transistor M2 is turned on.

[0040] Furthermore, a sixth voltage-stabilizing resistor RZ6 and a sixth voltage-stabilizing diode DZ6 connected in parallel are provided between the gate of the sixth field effect transistor M6 and its source, and the connection relationship and effect thereof are the same as the connection relationship and effect of the second voltage-stabilizing resistor RZ2 and the second voltage-stabilizing diode DZ2. It should be noted that the second field effect transistor M2 and the sixth field effect transistor M6 are connected in parallel to form a blocking charging MOS tube. In an actual circuit, the number of blocking charging MOS tubes is not limited to that in the current circuit diagram, and a plurality of field effect transistors are connected in parallel to form a blocking charging MOS tube.

[0041] like Figure 4 As shown, in one embodiment, the discharge subcircuit 100 further includes a filter resistor RF1 and a filter capacitor C1 connected in parallel, the first resistor R1 and the fifth resistor R5 are both connected to the discharge signal terminal GD through the filter resistor RF1, the upper end of the filter capacitor C1 is connected to the first end of the filter resistor RF1, and the lower end of the filter capacitor C1 is connected to the second end of the filter resistor RF1. When there is a signal input, the parallel filter resistor RF1 and the filter capacitor C1 can filter the signal to reduce the interference of the redundant signal, and at the same time play a role in stabilizing the voltage of the entire circuit to ensure the normal operation of the circuit.

[0042] like Figure 4 As shown, in one embodiment, the discharge subcircuit 100 further includes a stabilizing diode D1, an anode of the stabilizing diode D1 is connected to the second end of the main circuit current sensing resistor RG1, a cathode of the stabilizing diode D1 is connected to the first end of the first resistor R1, and a second end of the first resistor R1 is connected to the gate of the first field effect transistor M1, so as to prevent current backflow and stabilize the voltage of the entire circuit to ensure the normal operation of the entire circuit.

[0043] like Figure 5As shown, in one embodiment, the charging sub-circuit 200 further includes a seventh field effect transistor M7 and a seventh resistor R7, the drain of the seventh field effect transistor M7 is connected to the second end of the current detection resistor RG2 of the charging loop, the source of the seventh field effect transistor M7 is connected to the source of the fourth field effect transistor M4, and the gate of the seventh field effect transistor M7 is connected to the charging signal terminal GC through the seventh resistor R7. In this embodiment, the seventh field effect transistor M7 is a charging MOS tube. When the battery is charged, the charging sub-circuit 200 is powered on, a signal passes through the gate of the seventh field effect transistor M7 at the discharge signal terminal GD, the seventh field effect transistor M7 is turned on, and the third field effect transistor M3 is turned on at the same time.

[0044] Furthermore, a seventh voltage-stabilizing resistor RZ7 and a seventh voltage-stabilizing diode DZ7 connected in parallel are provided between the gate of the seventh field effect transistor M7 and its source, and the connection relationship and effect thereof are the same as the connection relationship and effect of the third voltage-stabilizing resistor RZ3 and the third voltage-stabilizing diode DZ3. It should be noted that the third field effect transistor M3 and the seventh field effect transistor M7 are connected in parallel to form a charging MOS tube. In an actual circuit, the number of charging MOS tubes is not limited to that in the current circuit diagram, and a plurality of field effect transistors are connected in parallel to form a charging MOS tube.

[0045] like Figure 5 As shown, in one embodiment, the charging sub-circuit 200 further includes an eighth field effect transistor M8 and an eighth resistor R8, the source of the eighth field effect transistor M8 is connected to the source of the seventh field effect transistor M7, the drain of the eighth field effect transistor M8 is connected to the charging negative electrode, and the gate of the eighth field effect transistor M8 is connected to the gate signal driving terminal GB through the eighth resistor R8. In this embodiment, the eighth field effect transistor M8 is a blocking discharge MOS tube. When the battery is charged, the charging sub-circuit 200 is powered on, and the gate signal driving terminal GB has a signal passing through the gate of the eighth field effect transistor M8, which is then turned on to prevent the discharge action from occurring in the charging sub-circuit 200, and at the same time, the fourth field effect transistor M4 is turned on.

[0046] Furthermore, an eighth voltage-stabilizing resistor RZ8 and an eighth voltage-stabilizing diode DZ8 connected in parallel are provided between the gate of the eighth field effect transistor M8 and its source, and the connection relationship and effect thereof are the same as the connection relationship and effect of the fourth voltage-stabilizing resistor RZ4 and the fourth voltage-stabilizing diode DZ4. It should be noted that the fourth field effect transistor M4 and the eighth field effect transistor M8 are connected in parallel to form a blocking discharge MOS tube. In an actual circuit, the number of blocking discharge MOS tubes is not limited to that in the current circuit diagram, and a plurality of field effect transistors are connected in parallel to form a blocking discharge MOS tube.

[0047] like Figure 5 As shown, in one embodiment, the charging sub-circuit 200 further includes a fuse resistor RP1, and the drain of the fourth field effect transistor M4 and the drain of the eighth field effect transistor M8 are both connected to the charging negative electrode C-1 through the fuse resistor RP1.

[0048] Furthermore, the rated current of the fuse resistor RP1 is 10 A. In this embodiment, the fuse resistor RP1 has the function of a common resistor when the entire circuit is normal. When the circuit is abnormal, it will disconnect the circuit to prevent further battery accidents. Specifically, when the current exceeds 10 A, the internal fuse will melt to disconnect the circuit to prevent the components of the circuit from being broken down due to excessive current.

[0049] The present disclosure also provides a lithium battery, including the charge and discharge current identification circuit 10 of any of the above embodiments, so that when the lithium battery is in a discharge state, the charge and discharge current identification circuit 10 can identify whether the current is a charging current or a feedback current through the cooperation of the main circuit current sampler 110 and the charging circuit current sampler 210.

[0050] Compared with the prior art, the present invention has at least the following advantages:

[0051] The charging and discharging current identification circuit 10 sets a charging circuit current detection resistor RG2 in the charging subcircuit 200, and the charging circuit current sampler 210 detects that when the vehicle is charging, the main circuit current sampler 110 detects that there is current passing through the main circuit current detection resistor RG1, and the charging circuit current sampler 210 detects that there is current passing through the charging circuit current detection resistor RG2, so the MCU identifies it as a charging current; when the vehicle is riding and braking, the main circuit current sampler 110 detects that there is current passing through the main circuit current detection resistor RG1, and the charging circuit current sampler 210 detects that there is no current in the charging circuit current detection resistor RG2, and then the MCU identifies it as a feedback current. In this way, it can accurately identify whether it is the charging current of the charging circuit or the feedback current of the discharging circuit, so that the charging protection parameters are accurately set, and there is no misjudgment or the protection range is increased, resulting in a weakening of the protection capability, thereby ensuring the normal use of the entire vehicle.

[0052] The above-mentioned embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the disclosed patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the disclosed patent shall be subject to the attached claims.

Claims

1. A charge and discharge current identification circuit, comprising a main circuit current sensing resistor and a discharge subcircuit, wherein the discharge subcircuit comprises a first field effect tube, a second field effect tube, a first resistor and a second resistor, wherein the two ends of the main circuit current sensing resistor are respectively connected to the two collection ends of the main circuit current collector, the first end of the main circuit current sensing resistor is grounded, the second end of the main circuit current sensing resistor is respectively connected to the source and the discharge signal end of the first field effect tube, the drain of the first field effect tube is connected to the drain of the second field effect tube, the gate of the first field effect tube is connected to the discharge signal end through the first resistor, the source of the second field effect tube is connected to the discharge negative electrode, and the gate of the second field effect tube is connected to the gate signal drive 1 end through the second resistor, characterized in that The charging and discharging current identification circuit also includes a charging subcircuit, which includes a third field effect tube, a fourth field effect tube, a third resistor, a fourth resistor and a charging circuit current detection resistor. The two ends of the charging circuit current detection resistor are respectively connected to the two collection ends of the charging circuit current collector, the first end of the charging circuit current detection resistor is connected to the second end of the main circuit current detection resistor, the second end of the charging circuit current detection resistor is connected to the drain of the third field effect tube, the source of the third field effect tube is connected to the source of the fourth field effect tube, the gate of the third field effect tube is connected to the charging signal end through the third resistor, the drain of the fourth field effect tube is connected to the charging negative electrode, and the gate of the fourth field effect tube is connected to the gate signal drive 2 end through the fourth resistor.

2. The charge and discharge current identification circuit according to claim 1, characterized in that: The discharge subcircuit also includes a fifth field effect transistor and a fifth resistor, the source of the fifth field effect transistor is connected to the second end of the main loop current detection resistor, the drain of the fifth field effect transistor is connected to the drain of the second field effect transistor, and the gate of the fifth field effect transistor is connected to the discharge signal end through the fifth resistor.

3. The charge and discharge current identification circuit according to claim 2, characterized in that: The discharge subcircuit also includes a sixth field effect tube and a sixth resistor, the drain of the sixth field effect tube is connected to the drain of the fifth field effect tube, the source of the sixth field effect tube is connected to the discharge cathode, and the gate of the sixth field effect tube is connected to the gate signal drive 1 terminal through the sixth resistor.

4. The charge and discharge current identification circuit according to claim 2, characterized in that: The discharge subcircuit also includes a filter resistor and a filter capacitor connected in parallel, the first resistor and the fifth resistor are both connected to the discharge signal end through the filter resistor, the upper end of the filter capacitor is connected to the first end of the filter resistor, and the lower end of the filter capacitor is connected to the second end of the filter resistor.

5. The charge and discharge current identification circuit according to claim 1, characterized in that: The discharge subcircuit also includes a stabilizing diode, an anode of the stabilizing diode is connected to the second end of the main loop current sensing resistor, a cathode of the stabilizing diode is connected to the first end of the first resistor, and a second end of the first resistor is connected to the gate of the first field effect transistor.

6. The charge and discharge current identification circuit according to claim 1, characterized in that: The charging sub-circuit also includes a seventh field effect transistor and a seventh resistor, the drain of the seventh field effect transistor is connected to the second end of the charging loop current detection resistor, the source of the seventh field effect transistor is connected to the source of the fourth field effect transistor, and the gate of the seventh field effect transistor is connected to the charging signal end through the seventh resistor.

7. The charge and discharge current identification circuit according to claim 6, characterized in that: The charging sub-circuit also includes an eighth field effect transistor and an eighth resistor, the source of the eighth field effect transistor is connected to the source of the seventh field effect transistor, the drain of the eighth field effect transistor is connected to the charging negative electrode, and the gate of the eighth field effect transistor is connected to the gate signal drive 2 terminal through the eighth resistor.

8. The charge and discharge current identification circuit according to claim 7, characterized in that: The charging subcircuit further includes a safety resistor, and the drain of the fourth field effect transistor and the drain of the eighth field effect transistor are both connected to the charging negative electrode through the safety resistor.

9. A lithium battery, characterized in that: It comprises the charge and discharge current identification circuit described in any one of claims 1 to 8.

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