A tractor potential equalization system and method of controlling the same

Abstract

The present application relates to tractor potential equalization technical field, disclose a kind of tractor potential equalization system and control method thereof.The present application is by constructing including high-voltage three electric systems, low-voltage electric appliance system, potential equalization management module, tractor chassis, whole vehicle controller and man-machine interactive unit's potential equalization system, using high-voltage branch voltage detection unit and low-voltage branch voltage detection unit respectively collect each high-voltage component and low-voltage component exposed conductive part's voltage signal, and output end is arranged in the chassis ground busbar place to form high-low voltage physical isolation, simultaneously with tractor chassis as the whole machine unified equipotential reference surface, solved new energy tractor along with traditional fuel tractor scattered bonding iron scheme causes the technical defects that potential difference between high-voltage components is difficult to effectively control, realized to high-voltage component and low-voltage component potential state real-time monitoring and hierarchical early warning, improve the electrical safety and operating reliability of tractor under complex agricultural operation scene.

Description

Technical Field

[0001] This invention relates to the field of tractor potential equalization technology, and in particular to a tractor potential equalization system and its control method. Background Technology

[0002] With the deepening of agricultural mechanization, new energy pure electric tractors and hybrid tractors have become the core development direction of agricultural equipment. Leveraging their advantages of low fuel consumption, low noise, high torque, and high control precision, they are gradually replacing traditional fuel-powered tractors and are widely used in all agricultural operations, including tillage, sowing, and plant protection. New energy tractors are equipped with a high-voltage three-electric system, with rated voltages generally ranging from 72V to 800V. This system includes components such as a power battery pack, motor, motor controller, high-voltage distribution unit (PDU), battery disconnect unit (BDU), and DC-DC converter. There are numerous exposed high-voltage conductive components, and they are widely distributed. However, most manufacturers in the industry still use the electrical design concepts of traditional fuel-powered tractors, simply copying the scattered grounding solutions without designing a dedicated potential balancing system for the special operating scenarios of tractors. This makes it difficult to effectively control the potential difference between high-voltage components, resulting in serious technical defects and safety hazards.

[0003] Therefore, there is an urgent need to provide a technical solution to address the above problems. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a tractor potential equalization system and its control method.

[0005] In a first aspect, the present invention provides a tractor potential equalization system, the technical solution of which is as follows: Includes: high-voltage three-electric system, low-voltage electrical system, potential equalization management module, tractor chassis, vehicle controller and human-machine interface unit; The high-voltage three-electric system includes multiple high-voltage components, the low-voltage electrical system includes multiple low-voltage components, and the vehicle controller is located in the low-voltage electrical system; The potential equalization management module includes a high-voltage branch voltage detection unit, a low-voltage branch voltage detection unit, a chassis grounding bus, and a CAN communication module. The exposed conductive parts of the multiple high-voltage components are respectively connected to different detection input terminals of the high-voltage branch voltage detection unit, and the output terminal of the high-voltage branch voltage detection unit is connected to the chassis grounding busbar; the exposed conductive parts of the multiple low-voltage components are respectively connected to different detection input terminals of the low-voltage branch voltage detection unit, and the output terminal of the low-voltage branch voltage detection unit is connected to the chassis grounding busbar. The output terminals of the high-voltage branch voltage detection unit and the low-voltage branch voltage detection unit are arranged separately at the chassis grounding busbar to form physical isolation between high and low voltage; the chassis grounding busbar is connected to the tractor chassis through an equipotential grounding wire, and the tractor chassis serves as a unified equipotential reference surface for the entire machine; The vehicle controller communicates with the high-voltage branch voltage detection unit and the low-voltage branch voltage detection unit via the CAN communication module. The vehicle controller is used for: Receive branch voltage data and calculate the connection resistance of each branch and the potential difference between any two branches; When it is determined that the connection resistance of any branch meets the first preset condition, a first-level early warning message is generated and sent to the human-machine interaction unit; When it is determined that the connection resistance of any branch meets the second preset condition, a secondary fault message is generated and sent to the human-machine interaction unit, and the output power of the whole vehicle is limited; When it is determined that the connection resistance of any branch meets the third preset condition, a three-level shutdown message is generated and sent to the human-machine interaction unit, and the high-voltage main contactor of the tractor is controlled to disconnect the power supply circuit of the high-voltage three-electric system.

[0006] The beneficial effects of the tractor potential equalization system of the present invention are as follows: The system of this invention constructs a potential balancing system comprising a high-voltage three-electric system, a low-voltage electrical system, a potential balancing management module, a tractor chassis, a vehicle controller, and a human-machine interface unit. It utilizes high-voltage branch voltage detection units and low-voltage branch voltage detection units to collect voltage signals from the exposed conductive parts of each high-voltage and low-voltage component. The output terminals are branched at the chassis grounding busbar to form physical isolation between high and low voltages. Simultaneously, the tractor chassis serves as a unified equipotential reference surface for the entire machine. This solves the technical defect of new energy tractors using the fragmented grounding scheme of traditional fuel tractors, which makes it difficult to effectively control the potential difference between high-voltage components. It achieves real-time monitoring and graded early warning of the potential status of high-voltage and low-voltage components, improving the electrical safety and operational reliability of the tractor in complex agricultural operation scenarios.

[0007] Based on the above scheme, the tractor potential equalization system of the present invention can be further improved as follows.

[0008] In one alternative approach, the high-voltage branch voltage detection unit injects a first constant current into the corresponding high-voltage component connection branch and acquires the voltage difference between the high-voltage component connection branch and the chassis grounding busbar through a differential amplifier circuit.

[0009] The advantages of adopting the above-mentioned optional method are as follows: by injecting a first constant current into the high-voltage component connection branch and combining it with the differential amplifier circuit to collect the voltage difference between the high-voltage component connection branch and the chassis grounding busbar, the online accurate measurement of the high-voltage branch connection resistance is realized, which improves the sensitivity and reliability of the high-voltage component potential status detection and provides an accurate basis for graded early warning.

[0010] In one alternative approach, the low-voltage branch voltage detection unit injects a second constant current into the corresponding low-voltage component connection branch and acquires the voltage difference between the low-voltage component connection branch and the chassis grounding busbar through a differential amplifier circuit.

[0011] The advantages of adopting the above-mentioned optional method are as follows: by injecting a second constant current into the low-voltage component connection branch and combining it with the differential amplifier circuit to collect the voltage difference between the low-voltage component connection branch and the chassis grounding busbar, the online accurate measurement of the low-voltage branch connection resistance is realized, the real-time monitoring capability of the low-voltage component potential status is improved, and the integrity of the high and low voltage full branch potential balance management is guaranteed.

[0012] In one alternative approach, the first preset condition is: the branch connection resistance is not less than the first-level warning threshold and less than the second-level fault threshold, wherein the first-level warning information includes the high-voltage branch identifier or low-voltage branch identifier to which the faulty branch belongs, which is used to remind the user to check the corresponding grounding line.

[0013] The beneficial effects of adopting the above-mentioned optional method are as follows: by further setting the trigger condition that the branch connection resistance is not less than the first-level warning threshold and less than the second-level fault threshold, the first-level warning information includes the high-voltage branch identifier or low-voltage branch identifier to which the faulty branch belongs, thus realizing the early identification and accurate location of the faulty branch, which makes it easier for operators to check the grounding line abnormalities in a timely manner.

[0014] In one alternative approach, the second preset condition is: the branch connection resistance is not less than the secondary fault threshold and less than the tertiary shutdown threshold, the secondary fault information includes the high-voltage branch identifier or low-voltage branch identifier to which the faulty branch belongs, and the limitation of the vehicle output power is a preset percentage that limits the vehicle output power to the rated power.

[0015] The advantages of adopting the above optional method are as follows: by setting the trigger condition that the branch connection resistance is not less than the secondary fault threshold and less than the tertiary shutdown threshold, the secondary fault information includes the high-voltage branch identifier or low-voltage branch identifier to which the faulty branch belongs, and the output power of the whole vehicle is limited to a preset percentage of the rated power, thus realizing power degradation protection under fault conditions and reducing safety risks.

[0016] In one alternative approach, the third preset condition is: the branch connection resistance is not less than the three-level shutdown threshold, or a high voltage is detected entering a low voltage branch; the vehicle controller controls the high voltage main contactor to disconnect the power supply circuit of the high voltage three-electric system, prohibiting the tractor from operating.

[0017] The beneficial effects of adopting the above-mentioned optional method are as follows: by setting the trigger condition that the branch connection resistance is not less than the three-level shutdown threshold, and by including the detection of high voltage entering low voltage branch in the third preset condition, the high voltage main contactor is controlled to disconnect the power supply circuit of the high voltage three-electric system when triggered, thus realizing the forced shutdown protection of serious faults and avoiding secondary safety accidents caused by high voltage entering low voltage.

[0018] In an alternative embodiment, the vehicle controller is further configured to: After the fault is resolved, the branch voltage data is re-acquired and the connection resistance of each branch is calculated. When the connection resistance of all branches is restored to below the first-level warning threshold, the restriction on the overall vehicle output power is lifted or the high-voltage main contactor is closed to restore the tractor to normal working condition.

[0019] The advantages of adopting the above-mentioned optional method are as follows: by re-collecting the branch voltage data and calculating the connection resistance of each branch after the fault is handled, when all the branch connection resistances are restored to below the first-level warning threshold, the restriction on the vehicle output power is lifted or the high-voltage main contactor is closed, thus realizing automatic recovery after fault removal, reducing manual intervention and improving the continuous operation capability of the system.

[0020] In an alternative embodiment, the vehicle controller is further configured to: The branch voltage data is received cyclically according to a preset cycle, and the connection resistance of each branch and the potential difference between any two branches are calculated. The potential equalization fault judgment and graded protection are performed cyclically.

[0021] The advantages of adopting the above-mentioned optional method are as follows: by receiving branch voltage data in a cyclical manner according to a preset cycle and calculating the connection resistance of each branch and the potential difference between any two branches, and cyclically performing potential balance fault judgment and graded protection, continuous dynamic monitoring of the overall potential status is realized, ensuring the real-time and continuous nature of potential balance management.

[0022] In one alternative approach, the potential equalization management module performs an internal self-test when the tractor potential equalization system is powered on. The internal self-test includes checking whether the acquisition circuit of the high-voltage branch voltage detection unit, the acquisition circuit of the low-voltage branch voltage detection unit, the communication circuit, and the power supply are normal.

[0023] The advantages of adopting the above-mentioned optional method are as follows: by performing an internal self-test of the potential equalization management module when the tractor potential equalization system is powered on, the system can detect whether the acquisition circuit of the high-voltage branch voltage detection unit, the acquisition circuit of the low-voltage branch voltage detection unit, the communication circuit and the power supply are normal. This enables pre-fault troubleshooting before system startup, avoids operation with defects, and improves the overall reliability of the system.

[0024] Secondly, the present invention provides a control method for a tractor potential equalization system, employing the tractor potential equalization system provided by the present invention. The technical solution of this method is as follows: Receive branch voltage data and calculate the connection resistance of each branch and the potential difference between any two branches; When it is determined that the connection resistance of any branch meets the first preset condition, a first-level early warning message is generated and sent to the human-machine interaction unit; When it is determined that the connection resistance of any branch meets the second preset condition, a secondary fault message is generated and sent to the human-machine interaction unit, and the output power of the whole vehicle is limited; When it is determined that the connection resistance of any branch meets the third preset condition, a three-level shutdown message is generated and sent to the human-machine interaction unit, and the high-voltage main contactor of the tractor is controlled to disconnect the power supply circuit of the high-voltage three-electric system.

[0025] The beneficial effects of the tractor potential equalization system control method of the present invention are as follows: The method of this invention solves the technical defect that the fragmented grounding scheme of traditional fuel tractors, which is used in new energy tractors, makes it difficult to effectively control the potential difference between high-voltage components. It realizes real-time monitoring and graded early warning of the potential status of high-voltage and low-voltage components, and improves the electrical safety and operational reliability of tractors in complex agricultural operation scenarios.

[0026] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0027] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic diagram of an embodiment of the tractor potential equalization system of the present invention; Figure 2 This is a schematic diagram of the working process of a tractor voltage equalization system; Figure 3This is a flowchart illustrating an embodiment of a tractor potential equalization system control method according to the present invention. Detailed Implementation

[0028] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0029] Figure 1 A schematic diagram of an embodiment of a tractor potential equalization system provided by the present invention is shown. Figure 1 As shown, the tractor potential equalization system includes: a high-voltage three-electric system 1, a low-voltage electrical system 2, a potential equalization management module 3, a tractor chassis 4, a vehicle controller 5, and a human-machine interaction unit 6.

[0030] The high-voltage three-electric system 1 includes multiple high-voltage components, the low-voltage electrical system 2 includes multiple low-voltage components, and the vehicle controller 5 is located in the low-voltage electrical system 2.

[0031] The high-voltage three-electric system 1 refers to the collective term for the high-voltage power conversion and drive system installed on the new energy tractor. For example, a high-voltage three-electric system 1 with a rated voltage of 400V includes a power battery pack, a motor, a motor controller, a high-voltage distribution box (PDU), a battery disconnection unit (BDU), and a DC-DC converter, providing traction power and high-voltage power distribution to the tractor. High-voltage components refer to devices in the high-voltage three-electric system 1 that independently perform power storage, conversion, drive, or distribution functions, and whose exposed conductive parts need to be connected to a potential balancing network. For example, the motor controller in the high-voltage three-electric system 1, as a high-voltage component, has its exposed conductive parts connected to a detection input terminal of the high-voltage branch voltage detection unit 31 via an independent branch line.

[0032] The low-voltage electrical system 2 refers to the general term for electrical control and auxiliary equipment on the new energy tractor that uses a nominal voltage of 12V or 24V for power supply. For example, the 24V low-voltage electrical system 2 includes the vehicle controller 5, low-voltage battery, instrument, display screen, and lighting components, and is responsible for the vehicle's logic control and information display. Low-voltage components refer to devices in the low-voltage electrical system 2 that independently perform control, display, lighting, or auxiliary functions, and whose exposed conductive parts need to be connected to a potential balancing network. For example, the instrument in the low-voltage electrical system 2 is a low-voltage component, and its exposed conductive parts are connected to a detection input terminal of the low-voltage branch voltage detection unit 32 via an independent branch line.

[0033] Among them, the vehicle controller 5 refers to an electronic control unit installed in the low-voltage electrical system 2, which communicates with the potential equalization management module 3 through the CAN communication module 34 and performs branch connection resistance calculation, potential difference calculation, graded protection judgment, and high-voltage main contactor control. For example, the vehicle controller 5 receives the branch voltage data collected by the high-voltage branch voltage detection unit 31 and the low-voltage branch voltage detection unit 32 at a period of 100ms, calculates that the resistance value of the motor controller connection branch is 0.12Ω, and generates a second-level fault information after determining that the second preset condition is met and limits the vehicle output power to 50% of the rated value.

[0034] The potential equalization management module 3 includes a high-voltage branch voltage detection unit 31, a low-voltage branch voltage detection unit 32, a chassis grounding bus 33, and a CAN communication module 34.

[0035] Among them, the potential equalization management module 3 refers to a combined device consisting of a high-voltage branch voltage detection unit 31, a low-voltage branch voltage detection unit 32, a chassis grounding busbar 33, and a CAN communication module 34. It is used to realize the functions of centralized current collection, voltage detection, and communication of the exposed conductive parts of the high-voltage and low-voltage components. For example, after the tractor is powered on by turning the key, the potential equalization management module 3 performs an internal self-test to check whether the acquisition circuit of the high-voltage branch voltage detection unit 31, the acquisition circuit of the low-voltage branch voltage detection unit 32, the communication circuit of the CAN communication module 34, and the power supply are normal.

[0036] The high-voltage branch voltage detection unit 31 refers to a unit located within the potential equalization management module 3, having multiple detection input terminals and an output terminal connected to the chassis grounding busbar 33, used to inject a constant current into the high-voltage component connection branch and collect the voltage difference. For example, after the high-voltage branch voltage detection unit 31 injects a first constant current of 100mA into the connection branch of the motor controller, it collects the voltage difference between the motor controller connection branch and the chassis grounding busbar 33 through a differential amplifier circuit. The vehicle controller 5 calculates the connection resistance of the motor controller connection branch based on the voltage difference and the 100mA current. The low-voltage branch voltage detection unit 32 refers to a unit located within the potential equalization management module 3, having multiple detection input terminals and an output terminal connected to the chassis grounding busbar 33. It is used to inject a constant current into the low-voltage component connection branch and collect the voltage difference. For example, after the low-voltage branch voltage detection unit 32 injects a second constant current of 50mA into the instrument connection branch, it collects the voltage difference between the instrument connection branch and the chassis grounding busbar 33 through a differential amplifier circuit. The vehicle controller 5 calculates the connection resistance of the instrument connection branch based on the voltage difference and the 50mA current. The chassis grounding busbar 33 refers to a conductor busbar located within the potential equalization management module 3, simultaneously connecting the output terminals of the high-voltage branch voltage detection unit 31, the low-voltage branch voltage detection unit 32, and the equipotential ground wire. For example, the chassis grounding busbar 33 separates the output terminals of the high-voltage branch where the motor controller is located and the low-voltage branch where the instrument is located, achieving physical isolation between high and low voltage, and then connects to the tractor chassis 4 through the equipotential ground wire. The CAN communication module 34 refers to the controller local area network communication interface set in the potential equalization management module 3, which is used to realize data transmission between the vehicle controller 5 and the high-voltage branch voltage detection unit 31 and the low-voltage branch voltage detection unit 32. For example, the CAN communication module 34 transmits the motor controller branch voltage data collected by the high-voltage branch voltage detection unit 31 and the instrument branch voltage data collected by the low-voltage branch voltage detection unit 32 to the vehicle controller 5 with a period of 100ms.

[0037] The exposed conductive parts of the multiple high-voltage components are respectively connected to different detection input terminals of the high-voltage branch voltage detection unit 31, and the output terminal of the high-voltage branch voltage detection unit 31 is connected to the chassis grounding busbar 33; the exposed conductive parts of the multiple low-voltage components are respectively connected to different detection input terminals of the low-voltage branch voltage detection unit 32, and the output terminal of the low-voltage branch voltage detection unit 32 is connected to the chassis grounding busbar 33.

[0038] The exposed conductive parts refer to the metal casings or conductive structural components on high-voltage or low-voltage components that operators may touch during normal operation. For example, the metal casing of the motor controller is an exposed conductive part, connected to a detection input terminal of the high-voltage branch voltage detection unit 31 via an independent branch line, ensuring that the motor controller casing and the tractor chassis 4 are at the same potential. The detection input terminal refers to the input interface on the high-voltage branch voltage detection unit 31 or the low-voltage branch voltage detection unit 32 used to receive voltage signals from the exposed conductive parts of the corresponding components. For example, one detection input terminal of the high-voltage branch voltage detection unit 31 is connected to the motor controller casing, and the other detection input terminal is connected to the high-voltage distribution box casing, with each detection input terminal being independent of the others.

[0039] The output terminal of the high-voltage branch voltage detection unit 31 and the output terminal of the low-voltage branch voltage detection unit 32 are arranged separately at the chassis grounding busbar 33 to form a physical isolation between high and low voltage; the chassis grounding busbar 33 is connected to the tractor chassis 4 through an equipotential grounding wire, and the tractor chassis 4 serves as a unified equipotential reference surface for the entire machine.

[0040] The high-voltage and low-voltage physical isolation refers to the structure where the output terminals of the high-voltage branch voltage detection unit 31 and the low-voltage branch voltage detection unit 32 are arranged separately on the chassis grounding busbar 33 and do not share the same busbar node. For example, the chassis grounding busbar 33 has independent high-voltage and low-voltage busbar areas. The motor controller branch and the high-voltage distribution box branch are connected to the high-voltage busbar area, while the instrument branch and the lighting component branch are connected to the low-voltage busbar area, thus forming high-voltage and low-voltage physical isolation. The equipotential grounding wire refers to a large-section wire connecting the chassis grounding busbar 33 and the tractor chassis 4, used to unify the potential of all branches on the busbar to the potential of the tractor chassis 4. For example, a 16mm² braided copper strip is used as the equipotential grounding wire, with one end fastened to the chassis grounding busbar 33 and the other end fastened to the tractor chassis 4.

[0041] Here, the tractor chassis 4 refers to the main metal frame structure of the new energy tractor, serving as the reference carrier for the unified equipotential reference surface of the entire machine. For example, the tractor chassis 4 is connected to the chassis grounding busbar 33 via an equipotential grounding wire. All exposed conductive parts, such as the motor controller housing and instrument housing, collected on the chassis grounding busbar 33 maintain the same potential as the tractor chassis 4. The equipotential reference surface refers to the reference potential surface that all exposed conductive parts in the entire machine are connected to through a centralized busbar and an equipotential grounding wire, ensuring that the resistance between any two exposed conductive parts is no greater than 0.1Ω. For example, when the tractor chassis 4 is used as the equipotential reference surface, the resistance between the motor controller housing and the instrument housing is 0.05Ω. When the insulation of the motor controller fails, no dangerous potential difference will be formed between the motor controller housing and the instrument housing.

[0042] The vehicle controller 5 communicates with the high-voltage branch voltage detection unit 31 and the low-voltage branch voltage detection unit 32 via the CAN communication module 34. The vehicle controller 5 is used for: Receive branch voltage data and calculate the connection resistance of each branch and the potential difference between any two branches.

[0043] Among them, the branch voltage data refers to the voltage difference between each branch of the vehicle controller 5 and the chassis ground busbar 33, which is collected and transmitted by the high voltage branch voltage detection unit 31 or the low voltage branch voltage detection unit 32 through the differential amplifier circuit; for example, the vehicle controller 5 receives 10mV motor controller branch voltage data transmitted by the high voltage branch voltage detection unit 31 through the CAN communication module 34.

[0044] The connection resistance refers to the resistance value of the connecting line between the exposed conductive parts of each component and the chassis grounding busbar 33, calculated according to Ohm's law based on the branch voltage data and the constant current value injected into the branch. For example, if the vehicle controller 5 receives a motor controller branch voltage data of 10mV and the first constant current injected by the high-voltage branch voltage detection unit 31 is 100mA, the calculated connection resistance of the motor controller branch is 0.1Ω. The potential difference refers to the voltage difference between any two different branches, used to determine whether the safety limit is exceeded. For example, the vehicle controller 5 calculates the potential difference between the motor controller branch and the instrument branch. When the voltage of the motor controller branch to the chassis grounding busbar 33 is 10mV and the voltage of the instrument branch to the chassis grounding busbar 33 is 2mV, the potential difference between the two branches is 8mV.

[0045] When it is determined that the connection resistance of any branch meets the first preset condition, a first-level early warning message is generated and sent to the human-machine interaction unit 6.

[0046] The first preset condition refers to the judgment condition used by the vehicle controller 5 when it determines that the connection resistance of any branch is not less than the first-level warning threshold and less than the second-level fault threshold. For example, if the vehicle controller 5 calculates that the connection resistance of the motor controller branch is 0.09Ω, the first-level warning threshold is 0.08Ω, and the second-level fault threshold is 0.1Ω, then 0.09Ω is not less than 0.08Ω and less than 0.1Ω, thus satisfying the first preset condition. The first-level warning information refers to the reminder information generated and sent to the human-machine interaction unit 6 when the vehicle controller 5 determines that any branch meets the first preset condition. This information includes the high-voltage branch identifier or low-voltage branch identifier of the faulty branch. For example, after the vehicle controller 5 determines that the motor controller branch meets the first preset condition, it generates a first-level warning information containing the identifier "High-voltage branch - motor controller branch" and sends it to the instrument display to show "Please check the motor controller grounding line".

[0047] Among them, the human-machine interaction unit 6 refers to an instrument, display screen or alarm used to display warning information, fault information and shutdown information to the operator; for example, the instrument, as the human-machine interaction unit 6, after receiving the first-level warning information sent by the vehicle controller 5, displays "Please check the motor controller grounding line" on the display screen.

[0048] When it is determined that the connection resistance of any branch meets the second preset condition, a secondary fault message is generated and sent to the human-machine interaction unit 6, and the output power of the whole vehicle is limited.

[0049] The second preset condition refers to the judgment condition used by the vehicle controller 5 when it determines that the connection resistance of any branch is not less than the secondary fault threshold and less than the tertiary shutdown threshold. For example, if the vehicle controller 5 calculates that the connection resistance of the motor controller branch is 0.12Ω, the secondary fault threshold is 0.1Ω, and the tertiary shutdown threshold is 0.5Ω, then 0.12Ω is not less than 0.1Ω and less than 0.5Ω, thus satisfying the second preset condition. The secondary fault information refers to the fault information generated and sent to the human-machine interaction unit 6 when the vehicle controller 5 determines that any branch meets the second preset condition. This information includes the high-voltage branch identifier or low-voltage branch identifier to which the faulty branch belongs. For example, after the vehicle controller 5 determines that the motor controller branch meets the second preset condition, it generates secondary fault information containing the identifier "high-voltage branch - motor controller branch" and sends it to the instrument display to show "motor controller grounding line fault, please stop work immediately and transfer to the repair point".

[0050] Among them, the total vehicle output power refers to the mechanical power output by the high-voltage three-electric system 1 of the new energy tractor to the traction motor; for example, the rated value of the total vehicle output power is 100kW. When the vehicle controller 5 determines that the motor controller branch meets the second preset condition, the total vehicle output power is limited to 50kW.

[0051] When it is determined that the connection resistance of any branch meets the third preset condition, a three-level shutdown information is generated and sent to the human-machine interaction unit 6, and the high-voltage main contactor of the tractor is controlled to disconnect the power supply circuit of the high-voltage three-electric system 1.

[0052] The third preset condition refers to the judgment condition used by the vehicle controller 5 when it determines that the connection resistance of any branch is not less than the three-level shutdown threshold or when it detects high voltage entering a low-voltage branch. For example, the vehicle controller 5 calculates that the connection resistance of the motor controller branch is 0.6Ω, the three-level shutdown threshold is 0.5Ω, and 0.6Ω is not less than 0.5Ω, thus satisfying the third preset condition. The three-level shutdown information refers to the shutdown information generated and sent to the human-machine interaction unit 6 when the vehicle controller 5 determines that any branch meets the third preset condition. This information includes the high-voltage branch identifier or low-voltage branch identifier to which the faulty branch belongs. For example, after the vehicle controller 5 determines that the motor controller branch meets the third preset condition, it generates three-level shutdown information containing the identifier "high-voltage branch - motor controller branch" and sends it to the instrument display to show "serious fault in motor controller grounding line, power off and shut down, operation prohibited".

[0053] The high-voltage main contactor refers to a switching device connected in series in the power supply circuit of the high-voltage three-electric system 1, controlled by the vehicle controller 5 to connect or disconnect the high-voltage power supply. For example, after the vehicle controller 5 determines that the motor controller branch meets the third preset condition, it sends a disconnect command to the high-voltage main contactor, which disconnects the power supply circuit between the power battery pack and the motor controller. The power supply circuit refers to the path of electrical energy transmission from the power battery pack through the high-voltage distribution box and the high-voltage main contactor to high-voltage components such as the motor controller in the high-voltage three-electric system 1. For example, after the high-voltage main contactor is disconnected, the power supply circuit from the power battery pack to the motor controller is cut off, and the vehicle loses traction power.

[0054] The technical solution of this embodiment constructs a potential balancing system comprising a high-voltage three-electric system, a low-voltage electrical system, a potential balancing management module, a tractor chassis, a vehicle controller, and a human-machine interface unit. It utilizes high-voltage branch voltage detection units and low-voltage branch voltage detection units to collect voltage signals from the exposed conductive parts of each high-voltage and low-voltage component. The output terminals are branched at the chassis grounding busbar to form physical isolation between high and low voltages. Simultaneously, the tractor chassis serves as a unified equipotential reference surface for the entire machine. This solves the technical defect of new energy tractors using the fragmented grounding scheme of traditional fuel tractors, which makes it difficult to effectively control the potential difference between high-voltage components. It achieves real-time monitoring and graded early warning of the potential status of high-voltage and low-voltage components, improving the electrical safety and operational reliability of the tractor in complex agricultural operation scenarios.

[0055] In one alternative approach, the high-voltage branch voltage detection unit 31 injects a first constant current into the corresponding high-voltage component connection branch and acquires the voltage difference between the high-voltage component connection branch and the chassis grounding busbar 33 through a differential amplifier circuit.

[0056] The first constant current refers to the known fixed current value injected by the high-voltage branch voltage detection unit 31 into the high-voltage component connection branch, which is used to calculate the branch connection resistance in conjunction with the voltage difference; for example, the high-voltage branch voltage detection unit 31 injects a first constant current of 100mA into the motor controller connection branch.

[0057] The differential amplifier circuit refers to a circuit installed in the high-voltage branch voltage detection unit 31 or the low-voltage branch voltage detection unit 32, used to collect the voltage difference between the branch and the chassis grounding busbar 33 and eliminate common-mode interference; for example, the differential amplifier circuit in the high-voltage branch voltage detection unit 31 collects the voltage difference between the motor controller connection branch and the chassis grounding busbar 33 to obtain a 10mV differential voltage signal.

[0058] In the above-mentioned optional methods, by injecting a first constant current into the high-voltage component connection branch and combining it with a differential amplifier circuit to collect the voltage difference between the high-voltage component connection branch and the chassis grounding busbar, the online accurate measurement of the high-voltage branch connection resistance is realized, which improves the sensitivity and reliability of the high-voltage component potential status detection and provides an accurate basis for graded early warning.

[0059] In one alternative, the low-voltage branch voltage detection unit 32 injects a second constant current into the corresponding low-voltage component connection branch and acquires the voltage difference between the low-voltage component connection branch and the chassis grounding busbar 33 through a differential amplifier circuit.

[0060] The second constant current refers to the known fixed current value injected by the low-voltage branch voltage detection unit 32 into the low-voltage component connection branch, which is used to calculate the branch connection resistance in conjunction with the voltage difference; for example, the low-voltage branch voltage detection unit 32 injects a second constant current of 50mA into the instrument connection branch, while the first constant current value injected into the high-voltage component connection branch is 100mA, and the two are different.

[0061] In the above-mentioned optional methods, by injecting a second constant current into the low-voltage component connection branch and combining it with a differential amplifier circuit to collect the voltage difference between the low-voltage component connection branch and the chassis grounding busbar, the online accurate measurement of the low-voltage branch connection resistance is realized, the real-time monitoring capability of the low-voltage component potential status is improved, and the integrity of the high and low voltage full branch potential balance management is ensured.

[0062] In one alternative approach, the first preset condition is: the branch connection resistance is not less than the first-level warning threshold and less than the second-level fault threshold, wherein the first-level warning information includes the high-voltage branch identifier or low-voltage branch identifier to which the faulty branch belongs, which is used to remind the user to check the corresponding grounding line.

[0063] The first-level warning threshold refers to the minimum resistance value used to determine whether the branch connection resistance triggers a first-level warning. For example, if the first-level warning threshold is 0.08Ω, the vehicle controller 5 calculates the connection resistance of the motor controller branch to be 0.09Ω, and 0.09Ω is not less than 0.08Ω. The second-level fault threshold refers to the minimum resistance value used to determine whether the branch connection resistance triggers a second-level fault, and also serves as the upper limit of the first-level warning range. For example, if the second-level fault threshold is 0.1Ω, the vehicle controller 5 calculates the connection resistance of the motor controller branch to be 0.12Ω, and 0.12Ω is not less than 0.1Ω.

[0064] High-voltage branch identification refers to the markings used in Level 1 warning messages, Level 2 fault messages, or Level 3 shutdown messages to indicate that the branch where the fault is located belongs to a high-voltage branch; for example, a Level 1 warning message may include "High-voltage branch—motor controller branch," where "high-voltage branch" is the high-voltage branch identification. Low-voltage branch identification refers to the markings used in Level 1 warning messages, Level 2 fault messages, or Level 3 shutdown messages to indicate that the branch where the fault is located belongs to a low-voltage branch; for example, a Level 1 warning message may include "Low-voltage branch—instrument branch," where "low-voltage branch" is the low-voltage branch identification.

[0065] The grounding line refers to the wire and connection point that connects the exposed conductive part of the high-voltage or low-voltage component to the chassis grounding busbar 33. For example, the motor controller housing is connected to the detection input terminal of the high-voltage branch voltage detection unit 31 via the grounding line, and then the output terminal of the high-voltage branch voltage detection unit 31 is connected to the chassis grounding busbar 33. The vehicle controller 5 calculates the connection resistance of the grounding line to be 0.09Ω.

[0066] In the above-mentioned optional methods, by further setting the trigger condition that the branch connection resistance is not less than the first-level warning threshold and less than the second-level fault threshold, the first-level warning information includes the high-voltage branch identifier or low-voltage branch identifier to which the faulty branch belongs, thus realizing the early identification and accurate location of the faulty branch, which facilitates operators to promptly check for abnormalities in the grounding line.

[0067] In one alternative approach, the second preset condition is: the branch connection resistance is not less than the secondary fault threshold and less than the tertiary shutdown threshold, the secondary fault information includes the high-voltage branch identifier or low-voltage branch identifier to which the faulty branch belongs, and the limitation of the vehicle output power is a preset percentage that limits the vehicle output power to the rated power.

[0068] The three-level shutdown threshold refers to the minimum resistance value used to determine whether the branch connection resistance triggers a three-level shutdown. For example, if the three-level shutdown threshold is 0.5Ω, the vehicle controller 5 calculates that the connection resistance of the motor controller branch is 0.6Ω, and 0.6Ω is not less than 0.5Ω.

[0069] Rated power refers to the maximum continuous power output of the high-voltage three-electric system 1 of the new energy tractor under normal operating conditions; for example, if the rated power of the new energy tractor is 100kW, when the vehicle controller 5 determines that any branch meets the second preset condition, the output power of the entire vehicle will be limited to 50kW. Preset percentage refers to the proportion of rated power used by the vehicle controller 5 when limiting the output power of the entire vehicle; for example, if the preset percentage is 50%, the vehicle controller 5 will limit the output power of the entire vehicle from 100kW to 50kW.

[0070] In the above-mentioned optional methods, by further setting the trigger condition that the branch connection resistance is not less than the secondary fault threshold and less than the tertiary shutdown threshold, the secondary fault information includes the high-voltage branch identifier or low-voltage branch identifier to which the faulty branch belongs, and the vehicle output power is limited to a preset percentage of the rated power, power degradation protection under fault conditions is realized, and safety risks are reduced.

[0071] In one alternative approach, the third preset condition is: the branch connection resistance is not less than the three-level shutdown threshold, or a high voltage is detected entering a low voltage branch; the vehicle controller 5 controls the high voltage main contactor to disconnect the power supply circuit of the high voltage three-electric system 1, prohibiting the tractor from operating.

[0072] In the above-mentioned optional methods, by further setting the trigger condition that the branch connection resistance is not less than the three-level shutdown threshold, and including the detection of high voltage entering low voltage branch in the third preset condition, the high voltage main contactor is controlled to disconnect the power supply circuit of high voltage three-electric system 1 when triggered, thereby realizing the forced shutdown protection of serious faults and avoiding secondary safety accidents caused by high voltage entering low voltage.

[0073] In an alternative embodiment, the vehicle controller 5 is further configured to: After the fault is resolved, the branch voltage data is re-acquired and the connection resistance of each branch is calculated. When the connection resistance of all branches is restored to below the first-level warning threshold, the restriction on the overall vehicle output power is lifted or the high-voltage main contactor is closed to restore the tractor to normal working condition.

[0074] The normal operating state refers to the state where, after all branch connection resistances have recovered to below the first-level warning threshold, the vehicle controller 5 releases the power limit or closes the high-voltage main contactor, and the tractor returns to a fault-free operating state. For example, after maintenance personnel handle the loose grounding line fault of the motor controller, the vehicle controller 5 re-collects the branch voltage data and calculates that the connection resistance of the motor controller branch is 0.05Ω, which is below the first-level warning threshold of 0.08Ω. The vehicle controller 5 then releases the power limit and closes the high-voltage main contactor, and the tractor returns to a normal operating state.

[0075] In the above-mentioned optional methods, the branch voltage data is re-acquired and the connection resistance of each branch is calculated after the fault is handled. When the connection resistance of all branches is restored to below the first-level warning threshold, the restriction on the vehicle output power is lifted or the high-voltage main contactor is closed. This achieves automatic recovery after fault removal, reduces manual intervention, and improves the continuous operation capability of the system.

[0076] In an alternative embodiment, the vehicle controller 5 is further configured to: The branch voltage data is received cyclically according to a preset cycle, and the connection resistance of each branch and the potential difference between any two branches are calculated. The potential equalization fault judgment and graded protection are performed cyclically.

[0077] The preset period refers to the time interval between the vehicle controller 5 receiving branch voltage data and performing potential equalization fault judgment and graded protection. For example, if the preset period is 100ms, the vehicle controller 5 receives branch voltage data once every 100ms through the CAN communication module 34, calculates the connection resistance of each branch and the potential difference between any two branches, and determines whether the first preset condition, the second preset condition or the third preset condition is met.

[0078] Among them, the potential balance fault judgment refers to the process by which the vehicle controller 5 compares the calculated connection resistance of each branch and the potential difference between any two branches with preset conditions to determine the fault level; for example, the vehicle controller 5 calculates that the connection resistance of the motor controller branch is 0.09Ω, compares 0.09Ω with the first-level warning threshold of 0.08Ω and the second-level fault threshold of 0.1Ω, and determines that the motor controller branch has triggered a first-level warning. Graded protection refers to the following: based on the potential balance fault judgment results, the vehicle controller 5 implements a gradient safety protection strategy of reminder, power limitation, and power-off shutdown for Level 1 warning, Level 2 fault, and Level 3 shutdown, respectively. For example, if the vehicle controller 5 determines that the connection resistance of the motor controller branch is 0.09Ω within a 100ms cycle, it will implement Level 1 warning protection, only reminding the user without restricting operation; if it determines that the connection resistance of the motor controller branch rises to 0.12Ω in the next 100ms cycle, it will implement Level 2 fault protection, limiting the vehicle output power to 50kW; if it determines that the connection resistance of the motor controller branch rises to 0.6Ω in the subsequent 100ms cycle, it will implement Level 3 shutdown protection, controlling the high-voltage main contactor to disconnect the power supply circuit.

[0079] In the above-mentioned optional methods, by cyclically receiving branch voltage data according to a preset cycle and calculating the connection resistance of each branch and the potential difference between any two branches, and cyclically performing potential balance fault judgment and graded protection, continuous dynamic monitoring of the overall potential status is realized, ensuring the real-time and continuous nature of potential balance management.

[0080] In one alternative approach, the potential equalization management module 3 performs an internal self-test when the tractor potential equalization system is powered on. The internal self-test includes checking whether the acquisition circuit of the high-voltage branch voltage detection unit 31, the acquisition circuit of the low-voltage branch voltage detection unit 32, the communication circuit, and the power supply are normal.

[0081] The internal self-test refers to the automatic detection of the circuit function of the potential equalization management module 3 when the tractor potential equalization system is powered on. For example, after the tractor is powered on by turning the key, the potential equalization management module 3 checks whether the acquisition circuit of the high voltage branch voltage detection unit 31 is normal, whether the acquisition circuit of the low voltage branch voltage detection unit 32 is normal, whether the communication circuit of the CAN communication module 34 is normal, and whether the power supply voltage is within the normal range.

[0082] The acquisition circuit refers to the circuit within the high-voltage branch voltage detection unit 31 or the low-voltage branch voltage detection unit 32 used to inject a constant current and acquire the voltage difference, including a constant current source and a differential amplifier circuit. For example, after the acquisition circuit of the high-voltage branch voltage detection unit 31 injects a first constant current of 100mA into the motor controller connection branch, the differential amplifier circuit acquires the voltage difference between the motor controller connection branch and the chassis grounding busbar 33. During internal self-test, it checks whether the constant current source output and the differential amplifier circuit are working properly.

[0083] In the above-mentioned optional methods, the internal self-test of the potential equalization management module is further performed when the tractor potential equalization system is powered on. This test checks whether the acquisition circuit of the high-voltage branch voltage detection unit, the acquisition circuit of the low-voltage branch voltage detection unit, the communication circuit, and the power supply are normal. This achieves pre-fault troubleshooting before system startup, avoids operation with defects, and improves the overall reliability of the system.

[0084] In this embodiment, it should be noted that: The high-voltage three-electric system 1 is the general term for the high-voltage power conversion and drive system installed on the new energy tractor. It includes a power battery pack, motor, motor controller, high-voltage distribution unit (PDU), battery disconnection unit (BDU), and DC-DC converter, with rated voltages ranging from 72V to 800V, providing traction power and high-voltage power distribution to the tractor. High-voltage components are devices in the high-voltage three-electric system 1 that independently perform power storage, conversion, drive, or distribution functions, and whose exposed conductive parts need to be connected to a potential balancing network. The high-voltage system has numerous exposed conductive parts that are widely distributed. The low-voltage electrical system 2 is the general term for the electrical control and auxiliary equipment on the new energy tractor that uses a nominal voltage of 12V or 24V. It includes the vehicle controller 5, low-voltage battery, instruments, display screen, and lighting components, responsible for vehicle logic control and information display. Low-voltage components are devices in the low-voltage electrical system 2 that independently perform control, display, lighting, or auxiliary functions, and whose exposed conductive parts need to be connected to a potential balancing network. The vehicle controller 5 is an electronic control unit located in the low-voltage electrical system. It communicates with the potential equalization management module 3 via the CAN communication module 34 and performs branch connection resistance calculation, potential difference calculation, graded protection judgment, and high-voltage main contactor control.

[0085] The high-voltage branch voltage detection unit 31 is located within the potential equalization management module 3. It has multiple detection input terminals and its output terminal is connected to the chassis grounding busbar 33. It is used to inject a constant current into the high-voltage component connection branch and collect the voltage difference. The low-voltage branch voltage detection unit 32 is located within the potential equalization management module 3. It has multiple detection input terminals and its output terminal is connected to the chassis grounding busbar 33. It is used to inject a constant current into the low-voltage component connection branch and collect the voltage difference. The chassis grounding busbar 33 is located within the potential equalization management module 3 and connects the output terminals of the high-voltage branch voltage detection unit 31, the low-voltage branch voltage detection unit 32, and the equipotential ground wire. It is a conductor device that collects the potentials of each branch. The CAN communication module 34 is located within the potential equalization management module 3 and is used to realize controller area network communication between the vehicle controller 5 and the high-voltage branch voltage detection unit 31 and the low-voltage branch voltage detection unit 32.

[0086] Exposed conductive parts are the metal casings or conductive structural components on high-voltage or low-voltage components that operators may touch during normal operation. The detection input terminal is the input interface on the high-voltage branch voltage detection unit 31 or the low-voltage branch voltage detection unit 32 used to receive voltage signals from the exposed conductive parts of the corresponding components; each detection input terminal is independent of the others. High- and low-voltage physical isolation refers to the structural form where the output terminals of the high-voltage branch voltage detection unit 31 and the low-voltage branch voltage detection unit 32 are arranged separately on the chassis grounding busbar 33 and do not share the same busbar node. The equipotential grounding wire is a large-section conductor connecting the chassis grounding busbar 33 and the tractor chassis 4; the cross-section uses a large area specification to ensure sufficiently low connection impedance. The tractor chassis is the main metal frame structure of the new energy tractor, serving as the reference carrier for the unified equipotential reference surface of the entire machine. The equipotential reference plane is a reference potential plane that is connected to by all exposed conductive parts in the whole machine through a centralized bus and an equipotential grounding wire, so that the resistance between any two exposed conductive parts is no greater than 0.1Ω, thus eliminating the risk of electric shock at the source.

[0087] The vehicle controller 5 communicates with the high-voltage branch voltage detection unit 31 and the low-voltage branch voltage detection unit 32 via the CAN communication module 34. The human-machine interface unit 6 is connected to the vehicle controller 5. The human-machine interface unit is an instrument, display screen, or alarm used to display warning information, fault information, and shutdown information to the operator. The vehicle controller 5 receives detection information from the potential equalization management module 3, calculates and processes the data, and determines whether it is normal. When a fault is detected, it communicates with the human-machine interface unit 6 and reports the fault information, while simultaneously controlling the high-voltage main contactor to close or open.

[0088] like Figure 2 As shown, the workflow of the tractor potential equalization system includes power-on initialization, data periodic acquisition, data calculation, potential equalization fault judgment, graded protection, and fault recovery judgment. During normal operation, the system cyclically executes the steps from data periodic acquisition to fault recovery judgment, realizing real-time monitoring and protection of potential equalization under all working conditions and at all times.

[0089] Specifically, during the power-on initialization phase, the tractor is started by turning the key, and the 12V or 24V low-voltage electrical system 2 is powered on. The potential equalization management module 3 and the vehicle controller 5 complete the power-on initialization. When the tractor's potential equalization system is powered on, the potential equalization management module 3 performs an internal self-test, checking whether the acquisition circuits of the high-voltage branch voltage detection unit 31 and the low-voltage branch voltage detection unit 32, the communication circuit, and the power supply are normal. The internal self-test is an automatic check of the potential equalization management module's own circuit functions when the system is powered on. The acquisition circuit is the circuit within the high-voltage branch voltage detection unit 31 or the low-voltage branch voltage detection unit 32 used to inject a constant current and acquire the voltage difference, including a constant current source and a differential amplifier circuit.

[0090] During the data acquisition phase, the vehicle controller 5 polls and collects voltage data from the high-voltage and low-voltage branches within the potential equalization management module 3 at a fixed period of 100ms. The data is then processed through digital filtering, amplification, and analog-to-digital conversion to obtain digital signals. The preset period is the time interval between the vehicle controller 5's cyclic reception of branch voltage data and the execution of potential equalization fault judgment and graded protection; the preset period is 100ms. The branch voltage data is the voltage difference between each branch of the vehicle controller 5 and the chassis grounding busbar 33, acquired by the high-voltage branch voltage detection unit 31 or the low-voltage branch voltage detection unit 32 through a differential amplifier circuit.

[0091] During the data calculation phase, the vehicle controller 5 calculates the connection resistance of each branch, the voltage difference between the branch and the reference ground, and the potential difference between any two branches based on the received branch voltage data. The connection resistance is the resistance value of the connecting lines between the exposed conductive parts of each component and the chassis ground busbar, calculated according to Ohm's law based on the branch voltage data and the constant current value injected into the branch. The potential difference is the voltage difference between any two different branches, used to determine whether safety limits are exceeded.

[0092] During the potential equalization fault judgment phase, the vehicle controller 5 compares the connection resistance values ​​of the high-voltage and low-voltage branches with preset thresholds to classify the fault levels. The graded protection involves the vehicle controller 5 executing a tiered protection strategy based on the potential equalization fault judgment results, including Level 1 warning, Level 2 fault, and Level 3 shutdown.

[0093] In the Level 1 warning stage, a Level 1 warning is triggered when the connection resistance of any branch is not less than the Level 1 warning threshold and is less than the Level 2 fault threshold. The vehicle controller 5 generates Level 1 warning information and pushes the reminder information and the fault identifier of the specific high-voltage or low-voltage branch to the human-machine interface unit 6, reminding the operator to check the corresponding grounding line. At this time, the reminder only does not affect the operation.

[0094] In the second-level fault stage, a second-level fault is determined when the connection resistance of any branch is not less than the second-level fault threshold and less than the third-level shutdown threshold. The vehicle controller 5 generates second-level fault information and pushes the fault information and the fault identifier of the specific high-voltage branch or low-voltage branch to the human-machine interface unit 6, limits the vehicle's output power to a preset percentage of the rated power, and reminds the operator to immediately stop work and move the tractor to a repair point to check and repair the corresponding grounding line.

[0095] During the Level 3 shutdown phase, a Level 3 fault is determined when the connection resistance of any branch is not less than the Level 3 shutdown threshold, or when high voltage is detected entering a low voltage branch. The vehicle controller 5 generates Level 3 shutdown information and sends it to the human-machine interface unit 6, which controls the high-voltage main contactor to disconnect the power supply circuit of the high-voltage three-electric system 1, thus shutting down the tractor and prohibiting its operation to avoid the risk of electric shock.

[0096] During the fault recovery judgment phase, after the fault handling is completed, the system re-executes the full branch detection. The vehicle controller 5 re-collects the branch voltage data and calculates the connection resistance of each branch. When the connection resistance of all branches is restored to below the first-level warning threshold, the vehicle controller 5 automatically releases the corresponding level of restriction, releases the power limit or controls the high-voltage main contactor to close, and restores the tractor to normal working state.

[0097] During the cyclic monitoring phase, the system continuously executes the steps from data cycle acquisition to fault recovery judgment during normal operation, realizing real-time monitoring and protection of potential balance for the tractor under all working conditions and at all times.

[0098] In the above workflow, the high-voltage branch voltage detection unit 31 injects a first constant current into the corresponding high-voltage component connection branch, and acquires the voltage difference between the high-voltage component connection branch and the chassis ground busbar 33 through a differential amplifier circuit. The vehicle controller 5 calculates the connection resistance of the corresponding branch according to Ohm's law based on the voltage difference and the first constant current. The low-voltage branch voltage detection unit 32 injects a second constant current into the corresponding low-voltage component connection branch, and acquires the voltage difference between the low-voltage component connection branch and the chassis ground busbar 33 through a differential amplifier circuit. The vehicle controller 5 calculates the connection resistance of the corresponding branch according to Ohm's law based on the voltage difference and the second constant current.

[0099] The Level 1 warning threshold is the minimum resistance value used to determine whether a branch connection resistance triggers a Level 1 warning. The Level 2 fault threshold is the minimum resistance value used to determine whether a branch connection resistance triggers a Level 2 fault, and also serves as the upper limit of the Level 1 warning range. The Level 3 shutdown threshold is the minimum resistance value used to determine whether a branch connection resistance triggers a Level 3 shutdown. The Level 1 warning threshold, Level 2 fault threshold, and Level 3 shutdown threshold are set with corresponding values ​​according to the actual situation of different models.

[0100] The following example illustrates the system's operation. Assume the tractor is a pure electric tractor. The rated voltage of the high-voltage three-electric system 1 is 400V, including the power battery pack, motor, motor controller, high-voltage distribution box PDU, battery disconnection unit BDU, and DC-DC converter. The low-voltage electrical system 2 is 24V, including the vehicle controller 5, low-voltage battery, instruments, display screen, and lighting components. The first-level warning threshold is set to 0.08Ω, the second-level fault threshold is set to 0.1Ω, and the third-level shutdown threshold is set to 0.5Ω. The preset percentage is 50%, and the rated power is 100kW.

[0101] After the tractor is powered on by turning the key, the potential equalization management module 3 performs an internal self-test, checking whether the acquisition circuits of the high-voltage branch voltage detection unit 31 and the low-voltage branch voltage detection unit 32, the communication circuit of the CAN communication module 34, and the power supply are normal. The vehicle controller 5 polls and acquires the branch voltage data of the high-voltage branch voltage detection unit 31 and the low-voltage branch voltage detection unit 32 at a period of 100ms. The high-voltage branch voltage detection unit 31 injects a first constant current of 100mA into the motor controller connection branch, and acquires the voltage difference between the motor controller connection branch and the chassis ground busbar 33 through a differential amplifier circuit, obtaining a voltage signal of 10mV. The low-voltage branch voltage detection unit 32 injects a second constant current of 50mA into the instrument connection branch, and acquires the voltage difference between the instrument connection branch and the chassis ground busbar 33 through a differential amplifier circuit, obtaining a voltage signal of 2mV. The CAN communication module 34 transmits the above voltage data to the vehicle controller 5.

[0102] The vehicle controller 5 calculates the connection resistance of each branch according to Ohm's law. The connection resistance R of the motor controller branch is equal to the voltage difference of 10mV divided by the first constant current of 100mA, resulting in 0.1Ω. The connection resistance R of the instrument branch is equal to the voltage difference of 2mV divided by the second constant current of 50mA, resulting in 0.04Ω. The vehicle controller 5 also calculates the potential difference between any two branches. The voltage of the motor controller branch to the chassis ground busbar 33 is 10mV, and the voltage of the instrument branch to the chassis ground busbar 33 is 2mV, resulting in a potential difference of 8mV between the two branches.

[0103] When the motor controller grounding line becomes slightly loose due to vibration, the connection resistance rises to 0.09Ω. The vehicle controller 5 determines that 0.09Ω is not less than 0.08Ω and less than 0.1Ω, which meets the first preset condition. It then generates a first-level warning message containing the identifier "High-voltage branch---motor controller branch" and sends it to the instrument display to show "Please check the motor controller grounding line". This is only a reminder and does not affect the operation.

[0104] When the grounding line becomes looser and the connection resistance rises to 0.12Ω, the vehicle controller 5 determines that 0.12Ω is not less than 0.1Ω and less than 0.5Ω, which meets the second preset condition. It then generates a level 2 fault message containing the identifier "high voltage branch - motor controller branch" and sends it to the instrument display to show "motor controller grounding line fault, please stop work immediately and transfer to the repair point". At the same time, it limits the vehicle's output power from 100kW to 50kW.

[0105] When the grounding line is severely corroded or broken, and the connection resistance rises to 0.6Ω, the vehicle controller 5 determines that 0.6Ω is not less than 0.5Ω, meeting the third preset condition. It then generates a Level 3 shutdown message containing the identifier "High-voltage branch --- motor controller branch," which is sent to the instrument panel displaying "Severe fault in motor controller grounding line, power off and shutdown, operation prohibited." Simultaneously, it controls the high-voltage main contactor to disconnect, cutting off the power supply circuit between the battery pack and the motor controller, causing the vehicle to lose traction power. If the vehicle controller 5 detects high-voltage interference in the low-voltage branch, it also determines it as a Level 3 fault and executes power-off shutdown protection.

[0106] After the maintenance personnel inspected and addressed the grounding fault in the motor controller, the vehicle controller 5 re-acquired the branch voltage data and calculated the connection resistance of each branch. When the connection resistance of the motor controller branch returned to 0.05Ω, which is lower than the first-level warning threshold of 0.08Ω, the vehicle controller 5 released the power limit and closed the high-voltage main contactor, and the tractor returned to normal operation.

[0107] Throughout the entire operation, the vehicle controller 5 continuously performs data acquisition, calculation, fault diagnosis, and graded protection in a preset cycle of 100ms, while monitoring the equipotential bonding status of high-voltage and low-voltage components in real time. As long as the resistance between any two exposed conductive components is no greater than 0.1Ω, even if the insulation of a high-voltage component fails, all exposed conductive components remain at the same potential, preventing the formation of a dangerous potential difference and ensuring the safety of operators.

[0108] Figure 3 This diagram illustrates a flowchart of an embodiment of a tractor potential equalization system control method provided by the present invention, employing the tractor potential equalization system provided by the present invention. Figure 3 As shown, the method includes the following steps: S1. Receive branch voltage data and calculate the connection resistance of each branch and the potential difference between any two branches. S21. When it is determined that the connection resistance of any branch meets the first preset condition, a first-level early warning message is generated and sent to the human-machine interaction unit. S22. When it is determined that the connection resistance of any branch meets the second preset condition, a secondary fault message is generated and sent to the human-machine interaction unit, and the output power of the whole vehicle is limited. S23. When it is determined that the connection resistance of any branch meets the third preset condition, a three-level shutdown information is generated and sent to the human-machine interaction unit, and the high-voltage main contactor of the tractor is controlled to disconnect the power supply circuit of the high-voltage three-electric system.

[0109] It should be noted that the beneficial effects of the tractor potential equalization system control method provided in the above embodiments are the same as those of the tractor potential equalization system described above, and will not be repeated here. Furthermore, the method and system embodiments provided in the above embodiments belong to the same concept, and their specific implementation process is detailed in the system embodiments, and will not be repeated here.

[0110] It should be understood that the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of methods and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0111] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this invention is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-disclosed concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this invention.

[0112] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and represent a limitation on a specific order or sequence. Where appropriate, the order of use for similar objects can be interchanged so that the embodiments of this application described herein can be implemented in an order other than that shown or described.

[0113] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A tractor potential equalization system, characterized in that, include: High-voltage three-electric system, low-voltage electrical system, potential equalization management module, tractor chassis, vehicle controller and human-machine interaction unit; The high-voltage three-electric system includes multiple high-voltage components, the low-voltage electrical system includes multiple low-voltage components, and the vehicle controller is located in the low-voltage electrical system; The potential equalization management module includes a high-voltage branch voltage detection unit, a low-voltage branch voltage detection unit, a chassis grounding bus, and a CAN communication module. The exposed conductive parts of the multiple high-voltage components are respectively connected to different detection input terminals of the high-voltage branch voltage detection unit, and the output terminal of the high-voltage branch voltage detection unit is connected to the chassis grounding busbar; the exposed conductive parts of the multiple low-voltage components are respectively connected to different detection input terminals of the low-voltage branch voltage detection unit, and the output terminal of the low-voltage branch voltage detection unit is connected to the chassis grounding busbar. The output terminals of the high-voltage branch voltage detection unit and the low-voltage branch voltage detection unit are arranged separately at the chassis grounding busbar to form physical isolation between high and low voltage. The chassis grounding busbar is connected to the tractor chassis via an equipotential grounding wire, and the tractor chassis serves as a unified equipotential reference surface for the entire machine. The vehicle controller communicates with the high-voltage branch voltage detection unit and the low-voltage branch voltage detection unit via the CAN communication module. The vehicle controller is used for: Receive branch voltage data and calculate the connection resistance of each branch and the potential difference between any two branches; When it is determined that the connection resistance of any branch meets the first preset condition, a first-level early warning message is generated and sent to the human-machine interaction unit; When it is determined that the connection resistance of any branch meets the second preset condition, a secondary fault message is generated and sent to the human-machine interaction unit, and the output power of the whole vehicle is limited; When it is determined that the connection resistance of any branch meets the third preset condition, a three-level shutdown message is generated and sent to the human-machine interaction unit, and the high-voltage main contactor of the tractor is controlled to disconnect the power supply circuit of the high-voltage three-electric system.

2. The tractor potential equalization system according to claim 1, characterized in that, The high-voltage branch voltage detection unit injects a first constant current into the corresponding high-voltage component connection branch and collects the voltage difference between the high-voltage component connection branch and the chassis grounding busbar through a differential amplifier circuit.

3. The tractor potential equalization system according to claim 2, characterized in that, The low-voltage branch voltage detection unit injects a second constant current into the corresponding low-voltage component connection branch and collects the voltage difference between the low-voltage component connection branch and the chassis grounding busbar through a differential amplifier circuit.

4. The tractor potential equalization system according to claim 1, characterized in that, The first preset condition is: the branch connection resistance is not less than the first-level warning threshold and less than the second-level fault threshold. The first-level warning information includes the high-voltage branch identifier or low-voltage branch identifier to which the faulty branch belongs, which is used to remind you to check the corresponding grounding line.

5. The tractor potential equalization system according to claim 4, characterized in that, The second preset condition is: the branch connection resistance is not less than the secondary fault threshold and less than the tertiary shutdown threshold, the secondary fault information includes the high-voltage branch identifier or low-voltage branch identifier to which the faulty branch belongs, and the limitation of the vehicle output power is a preset percentage of limiting the vehicle output power to the rated power.

6. The tractor potential equalization system according to claim 5, characterized in that, The third preset condition is: the branch connection resistance is not less than the three-level shutdown threshold, or a high voltage is detected to be inserted into the low voltage branch; the vehicle controller controls the high voltage main contactor to disconnect the power supply circuit of the high voltage three-electric system, prohibiting the tractor from operating.

7. The tractor potential equalization system according to claim 6, characterized in that, The vehicle controller is also used for: After the fault is resolved, the branch voltage data is re-acquired and the connection resistance of each branch is calculated. When the connection resistance of all branches is restored to below the first-level warning threshold, the restriction on the overall vehicle output power is lifted or the high-voltage main contactor is closed to restore the tractor to normal working condition.

8. The tractor potential equalization system according to claim 1, characterized in that, The vehicle controller is also used for: The branch voltage data is received cyclically according to a preset cycle, and the connection resistance of each branch and the potential difference between any two branches are calculated. The potential equalization fault judgment and graded protection are performed cyclically.

9. The tractor potential equalization system according to claim 1, characterized in that, The potential equalization management module performs an internal self-test when the tractor potential equalization system is powered on. The internal self-test includes checking whether the acquisition circuit of the high-voltage branch voltage detection unit, the acquisition circuit of the low-voltage branch voltage detection unit, the communication circuit, and the power supply are normal.

10. A control method for a tractor potential equalization system, characterized in that, The method of using the tractor potential equalization system as described in any one of claims 1 to 9 includes: Receive branch voltage data and calculate the connection resistance of each branch and the potential difference between any two branches; When it is determined that the connection resistance of any branch meets the first preset condition, a first-level early warning message is generated and sent to the human-machine interaction unit; When it is determined that the connection resistance of any branch meets the second preset condition, a secondary fault message is generated and sent to the human-machine interaction unit, and the output power of the whole vehicle is limited; When it is determined that the connection resistance of any branch meets the third preset condition, a three-level shutdown message is generated and sent to the human-machine interaction unit, and the high-voltage main contactor of the tractor is controlled to disconnect the power supply circuit of the high-voltage three-electric system.

Images