Method for uninterruptedly driving underground dual-power electric vehicle in power failure area

Abstract

The invention discloses a method for uninterruptedly driving an underground dual-power electric vehicle in a power failure area, which relates to the technical field of underground rail transit transportation and comprises the following steps of: optimizing a circuit framework of a tramcar, and changing a power supply loop of a hydraulic oil pump inverter and a 750VDC-24VDC direct converter into a power supply loop from a battery pack; an emergency stop protection logic is optimized, an automatic reset function of a safety relay circuit is set, wireless communication signal strength judgment is accessed to emergency stop control, and signals such as an emergency stop command are filtered; automatic pre-charging of a motor controller is controlled through MECU logic, and a pre-charging strategy is adjusted in combination with pantograph voltage and battery pack voltage parameters; according to the invention, the problem that the locomotive continuously slides without stopping when the underground tramcar in a pantograph and battery pack dual-power mode passes through a partition switch position or a poor sliding contact line contact area in a remote unmanned driving mode in the field of underground mining and mountain mining is solved.

Description

Technical Field

[0001] The invention relates to the technical field of underground rail transportation, in particular to a method for an underground dual-powered tram to travel uninterruptedly through a power-off zone. Background Art

[0002] Currently, underground mines generally use single-powered trams, such as those powered by pantographs or batteries. Large underground mines have densely packed loading chutes, with long stretches of conductor-free areas within the mines. Therefore, electric locomotives require auxiliary power units (APUs). A current solution is a dual-powered system using both pantographs and batteries, ensuring continued power even after the pantographs are lowered.

[0003] The locomotive adopts a dual power mode. In normal mode, the locomotive can be controlled to run continuously by manually controlling the switching of the pantograph and the battery pack. However, a zone switch is arranged every 500 meters on the underground transportation line. The busbar at the zone switch position is not continuous, but is connected by a 30cm long insulating wood. When the tram passes this position and the pantograph contacts the insulating wood, the pantograph will not be energized, or there will be a momentary short-distance power outage in the area where the busbar and the pantograph are not in good contact. This is an abnormal pantograph power outage. If there is no time to switch the battery pack, the locomotive's DCDC unit, inverter, motor controller and other main equipment will be powered off. Therefore, the locomotive will report a fault and stop suddenly, resulting in an unsmooth operation.

[0004] In the existing model, when a pantograph + battery pack dual-powered tram is in remote unmanned driving mode, power outages may occur when passing through areas with poor contact between the busbar and the pantograph, or areas with poor insulation of the zone switch. This can cause power outages in the vehicle's main power drive equipment, such as the DC / DC converter, inverter, and motor controller, and trigger an emergency stop for the tram. On each operating route, there may be multiple such points, resulting in multiple emergency stops, causing the tram to operate unsmoothly and fail to achieve optimal transportation efficiency. In view of this, by modifying the locomotive's hardware circuits and developing and upgrading software functions, with the goal of achieving uninterrupted locomotive operation through abnormal power outage areas, a targeted application invention has been developed. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for an underground dual-powered tram to travel uninterruptedly through a power-off zone, so as to solve the problems raised in the above-mentioned background technology.

[0006] To solve the above technical problems, the present invention provides a method for an underground dual-powered tram to continuously travel through a power outage area. The method is applied to an underground tram in a pantograph + battery pack dual-power mode, and the tram is in a remote unmanned operation state. By improving the hardware circuit and upgrading the software function, the tram can continuously glide in an abnormal power outage area. The method specifically includes the following steps:

[0007] Optimize the tram's circuit architecture and switch the power supply circuits for the hydraulic oil pump inverter and 750VDC to 24VDC converter to be drawn from the battery pack;

[0008] Optimize the emergency stop protection logic, set the automatic reset function of the safety relay circuit, and integrate the wireless communication signal strength judgment into the emergency stop control to filter the emergency stop command and other signals;

[0009] Automatically precharge the motor controller through MECU logic control, and adjust the precharge strategy based on the pantograph voltage and battery pack voltage parameters;

[0010] Optimize the switching mechanism between the pantograph and the battery pack, and give priority to entering the coasting mode in the event of an abnormal power outage.

[0011] Furthermore, the optimization of emergency stop protection logic specifically includes:

[0012] The wireless communication signal strength collected by ATO is lower than 40% and lasts for 2 seconds as the emergency stop trigger condition, and jump filtering is adopted for the emergency stop command and heartbeat data signal, and double protection is implemented through the positive and negative poles of the coil of the safety relay and the signal collection point.

[0013] Furthermore, the MECU processes the fault signal including:

[0014] The oil pump inverter fault signal and the direct current converter fault signal are de-jittered and filtered, and the hydraulic system pressure of 80-150bar is used as the fault judgment factor. The inverter is allowed to reset through the CAN bus within 10 seconds. If the reset is invalid, a fault signal is output.

[0015] Furthermore, the automatic pre-charging step includes:

[0016] After detecting the key switch signal and the remote ATO mode signal is enabled, the pre-charge circuit contactor is attracted;

[0017] When the pantograph voltage is lower than 600V and the battery pack voltage is higher than 500V, the pre-charging resistor is connected and the drive contactor is disconnected;

[0018] The system switches to coasting control mode according to the driving speed. When the DCDC output voltage reaches 564V and the motor controller voltage reaches 500V, the pre-charge resistor is isolated and the drive contactor is turned on.

[0019] Furthermore, the switching mechanism between the pantograph and the battery pack includes:

[0020] The pantograph status is determined by the push rod motor encoder data. When the pantograph voltage is lower than 600V, it is determined as an abnormal power outage and the vehicle enters coasting mode. During the coasting stage, the battery pack only supplies power to the on-board control power supply. If the DCDC does not work normally, the battery pack will be put into the motor controller drive circuit.

[0021] Furthermore, it also includes current limiting control for battery pack discharge:

[0022] In long-range mode, the speed is forcibly limited to 7 km / h, and the maximum current of the motor controller is limited to 120A. When the discharge current reaches 150A, acceleration is canceled and the vehicle switches to a constant speed for 10 seconds. If the current still exceeds the limit during the second acceleration, the vehicle enters current limiting mode with the battery pack current as the maximum limit.

[0023] Furthermore, speed control in remote mode includes:

[0024] If the speed drops during coasting due to an abnormal power outage, the remote control target value is given with reference to the actual speed;

[0025] After the coasting mode is switched to the battery pack mode, the actual speed at the end of the coasting is used as the starting point and the speed is gradually increased to the target speed in a ramp manner.

[0026] Furthermore, the ATO control unit and MECU control unit are programmed through the IQUNdesigne platform and use the J1939 communication protocol to exchange data with the DCDC, motor controller, and inverter for control command transmission and status information collection.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] Directly solve the key pain points in the underground mining field: through the integrated improvement of software and hardware, completely solve the emergency stop problem of underground trams with dual power mode of pantograph + battery pack in remote unmanned driving mode when passing through abnormal power outage scenarios such as the insulation wood area of ​​zoning switch and poor contact area of ​​trolley busbar, and realize continuous sliding of the locomotive without stopping, subverting the operation bottleneck of traditional dual power mode under power outage conditions.

[0029] Systematic improvement of software and hardware coordination: Based on the principle of the 55T locomotive body, through hardware circuit reconstruction (such as the hydraulic oil pump inverter and DCDC power supply are independently powered by the battery pack) and software function upgrades (such as automatic pre-charge logic and emergency stop protection filtering algorithm), a dual-power continuous operation protection method suitable for abnormal power outage conditions on site has been constructed, breaking through the limitations of traditional solutions that rely on manual switching.

[0030] Intelligent continuous operation in unmanned driving mode: For the first time, a dual-powered tram can automatically identify and seamlessly switch to abnormal power-off areas such as zone switches in unmanned driving mode, maintaining continuous operation of the locomotive without human intervention, significantly improving the level of automation in underground transportation.

[0031] Optimized circuit architecture and power stability: Improved power independence: The hydraulic pump inverter and DC-DC converter power supply circuits are moved from the shared DC bus to the battery pack, ensuring continuous control power supply during a momentary DC bus power loss, avoiding sudden stops caused by power interruptions. Automatic pre-charge function design: Combining the pre-charge resistor with the characteristics of the motor controller capacitor, an automatic pre-charge mechanism is designed after a power outage, allowing the motor controller to return to standby mode without manual intervention, shortening fault recovery time.

[0032] Control logic and signal processing upgrades: Emergency stop protection logic optimization: Introducing a wireless signal strength threshold (a signal strength below 40% for two seconds triggers an emergency stop), and filtering and anti-jitter processing for emergency stop commands and heartbeat data, reducing false operations caused by electromagnetic interference and the frequency of equipment emergency stops. J1939 communication protocol standardization: Developing an application-layer communication protocol between the ATO and MECU to enable real-time exchange of control commands, reset signals, and status data, ensuring stable and reliable data transmission in remote mode.

[0033] Improved hydraulic and power system reliability: Hydraulic system fault mitigation mechanism: Accumulator pressure monitoring and inverter fault signal debounce are used to classify faults (pressure anomalies take precedence over transient inverter faults). This allows the inverter to automatically reset within 10 seconds, preventing false hydraulic system fault reports that could affect braking performance during power outages. Battery pack safety control strategy: In remote mode, the speed is limited to ≤7 km / h and the motor current is ≤120A. Real-time discharge current monitoring is implemented (constant speed operation is forced when the current reaches 150A) to prevent excessive battery discharge and extend battery life.

[0034] Both transportation efficiency and safety are improved: the problem of frequent emergency stops in underground transportation routes is eliminated, the smoothness of single-trip operation routes is improved, and safety risks such as equipment collisions and battery loss caused by emergency stops are reduced, thereby extending the equipment service life.

[0035] Technical reference value across tonnage levels: It provides a reusable technical paradigm for the dual-power design of trams of different tonnages in underground mining, which is especially suitable for complex underground working conditions with dense chutes and discontinuous busbars, and promotes the upgrading of the industry's automated transportation technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The diagram is a schematic diagram of the principle of the method for an underground dual-powered electric vehicle to travel continuously through a power outage area according to the present invention. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] See also Figure 1 , the present invention provides a technical solution:

[0039] See Figure 1 As shown, an embodiment of a method for an underground dual-powered electric vehicle to travel continuously through a power outage area is as follows:

[0040] 1. Hardware circuit improvement:

[0041] In some specific implementations of this application, circuit architecture optimization: power supply independence reconstruction:

[0042] The original common DC bus was taken from the pantograph input (750VDC). After the improvement, the hydraulic oil pump inverter (power 30kW) and 750VDC / 24VDC direct converter (rated current 5A) were connected to the battery pack (600VDC lithium battery pack, capacity 200Ah) through independent cables. A 100A fast fuse and solid-state relay (SSR) were installed at the output end of the battery pack to achieve fault isolation of the power supply circuit.

[0043] The cable selection adopts oil-resistant armored cable (cross-sectional area 25mm 2 ), with a withstand voltage rating of ≥1000VDC to ensure high current transmission stability; the DC bus is physically isolated from the battery pack power supply circuit to avoid electromagnetic interference.

[0044] It should be noted here that:

[0045] Traditional dual-powered electric vehicles rely on the pantograph's DC busbar for control power, forcing them to shut down if power is lost. This method reconfigures the power supply circuit, allowing the hydraulic system and control power supply to continue to be independently powered by batteries even when the pantograph loses power, thus overcoming the technical bottleneck of "shutdown upon power outage."

[0046] In some specific implementations of this application, the following are also included: emergency stop protection logic optimization: dual hardware protection and signal filtering:

[0047] Among them, the safety relay circuit is improved:

[0048] The original safety relay (model PNOZX2.8) only controls the positive pole of the coil via the MECU. After improvement, a negative pole control circuit for the coil is added (via an independent relay K2), and an RC absorption circuit (R = 100Ω, C = 0.1μF) is connected in parallel at both ends of the relay contacts to suppress switching surges.

[0049] A voltage sensor (accuracy ±0.5%) is added to the signal collection point to monitor the relay coil voltage and contact status in real time, and triple verification of "positive pole control-negative pole feedback-contact monitoring" is achieved through dual-channel ADC sampling.

[0050] Signal filtering algorithm:

[0051] A second-order Butterworth low-pass filter (cut-off frequency 10 Hz) is used for the emergency stop command and heartbeat signal. The signal transition threshold is set in the software (if the 24 VDC signal fluctuation exceeds ±3 V, the filter is triggered), and the filter time constant τ = 0.5 s to eliminate false triggering caused by underground electromagnetic interference (such as spike noise when the motor starts).

[0052] For the first time, wireless signal strength (<40% and lasting for 2s) is used as the emergency stop trigger condition. Combined with hardware dual protection and signal filtering, it solves the problem of traditional emergency stop logic malfunctioning due to momentary interference.

[0053] In some specific embodiments of the present application, hydraulic system fault handling: accumulator pressure grading and fault mitigation, includes:

[0054] 3.1. Accumulator configuration:

[0055] A 2L bladder-type accumulator (operating pressure 160 bar) is installed in parallel with the hydraulic pump outlet. When the system pressure drops below 150 bar, the accumulator automatically replenishes oil, ensuring stability in the 80-150 bar pressure range. The pressure sensor (accuracy ±1 bar) has a sampling frequency of 100Hz, and data is transmitted to the MECU via the CAN bus.

[0056] 3.2 Fault classification logic:

[0057] When the inverter fault signal and pressure abnormality appear at the same time, the pressure abnormality is judged first (the pressure sensor has a higher priority than the inverter fault signal input in the hardware); when the inverter fails, the MECU sends a reset command through the CAN bus (10 times / 10s). If the reset is successful, the fault is cleared, otherwise a hard-wired fault signal is output to the emergency stop circuit.

[0058] It is necessary to add the following explanations here:

[0059] In traditional solutions, inverter failures trigger emergency stops. This method uses pressure grading and fault reset mechanisms to distinguish inverter failures caused by momentary power outages (non-permanent failures) from hydraulic system failures, avoiding unnecessary shutdowns caused by brief power outages.

[0060] In some specific implementations of the present application, it also includes: software logic upgrade: expansion of algorithms and processes.

[0061] Among them, the extended algorithm and process include: the motor controller automatically pre-charges the pre-charge strategy to adapt the dynamic parameters:

[0062] Specifically including: pre-charge resistor selection;

[0063] The pre-charge resistor uses a 100Ω / 500W power resistor. The pre-charge time constant τ = RC = 0.22s is calculated based on the battery pack voltage (600V) and the motor controller capacitance (total capacity 2200μF). This ensures that the charging current is ≤ 6A (much lower than the rated current of the motor controller of 300A) to avoid high current shock.

[0064] Precharge state machine control;

[0065] -->Detection enable;

[0066] Detection enable --> Pull in pre-charge contactor: key switch + ATO mode is valid;

[0067] Pull in the pre-charge contactor --> Voltage judgment: connect the pre-charge resistor;

[0068] Voltage judgment-->slip control: pantograph voltage <600V and battery pack >500V;

[0069] Slip control --> DCDC reset: enter standby mode;

[0070] DCDC reset --> Voltage compliance judgment: DCDC output ≥ 564V and motor controller ≥ 500V;

[0071] Voltage compliance judgment-->Isolation pre-charge resistance: Turn on the drive contactor;

[0072] Isolate pre-charge resistance-->Pre-charge successful: Check contactor status;

[0073] Precharge successful.

[0074] It should be noted here that:

[0075] Traditional pre-charging requires manual operation. This method realizes a fully automated process of "power off-pre-charging-ready" through the linkage of multiple parameters such as voltage and speed. The pre-charging time is shortened from 30 seconds in manual operation to less than 5 seconds, significantly improving the response speed.

[0076] In some specific implementations of the present application, pantograph and battery pack switching: encoder fusion and current limiting strategy are also included:

[0077] Encoder fusion and current limiting strategies include:

[0078] The actuator motor encoder (resolution 1024 lines) transmits position data in real time via the 485 bus. The software sets the bow raising threshold (encoder value > 1500) and bow lowering threshold (< 500), and uses Kalman filtering to fuse the encoder position and voltage signals to eliminate misjudgments caused by mechanical jitter (filter error ≤ ± 2 lines).

[0079] When the battery discharge current I≥150A, the following logic is executed:

[0080] A. Current limiting trigger conditions: Current threshold judgment:

[0081] Trigger condition: When the battery discharge current is \(I\geq150A\), current limiting protection is started.

[0082] Threshold setting: The rated maximum discharge current of a battery pack is usually 120A (for example, for a 600VDC / 200Ah lithium battery pack, 120A corresponds to a 0.6C discharge rate, which is within the safe discharge range).

[0083] 150A is the overload threshold (exceeding 25% of the rated value). If no intervention is taken at this time, it may cause a sudden rise in battery temperature, a reduction in battery life, and even safety risks (such as electrolyte decomposition).

[0084] B. Level 1 current limiting: cancel acceleration and maintain constant speed:

[0085] The present application eliminates the acceleration current surge through the above embodiment: during acceleration, the motor torque requirement increases, which causes the discharge current to rise further. Setting the target speed to the current speed means that the motor controller no longer outputs acceleration commands, preventing the current from continuing to rise.

[0086] Reserved current recovery time: During constant speed operation, the motor's power demand is stable (overcoming only friction and resistance), and the current typically decreases. A 10-second delay provides the system with a "buffer period." If the current drops below 150A during this period, the current limit is automatically released.

[0087] Avoid triggering false current limiting due to brief current fluctuations (such as when starting a ramp or sudden load changes) to ensure smooth driving. For example, when a tram is climbing a slope, the current may momentarily exceed 150A, but after running at a constant speed, the current will naturally decrease, and there is no need to enter strict current limiting mode at this time.

[0088] C. Secondary current limiting: Deep current limiting (if primary current limiting fails):

[0089] Trigger condition: If the current is still ≥150A after 10 seconds of constant speed operation, it indicates that the battery is in a continuous overload state (such as long-term climbing or increased internal resistance due to battery aging).

[0090] The control logic includes:

[0091] Dynamically obtain the maximum allowable current.

[0092] Current loop hard limit: A preset function directly acts on the current loop of the motor controller to force the maximum motor input current to a preset value. Regardless of the target speed, the motor current will not exceed this value.

[0093] Even under extreme working conditions, the current can be controlled within the battery safety range to prevent battery life degradation caused by over-discharge (for example, over-discharge of lithium batteries can cause lithium deposition at the negative electrode, posing a safety hazard).

[0094] D. Systematic considerations of logic design:

[0095] ①. Hierarchical flow control: Level 1 flow control (uniform speed buffering) takes precedence over level 2 flow control (hard flow control) to avoid frequent triggering of strict flow control and ensure transportation efficiency.

[0096] The 10-second delay is based on the battery's thermal characteristics: short-term overloads (<10 seconds) limit the battery temperature rise and eliminate the need for immediate power cutoff. However, sustained overloads require forced current limiting.

[0097] ②. Collaboration with other control strategies:

[0098] Combined with the speed limit (7km / h) in long-range mode, the current-limiting algorithm protects the battery from a dual-dimensional perspective: speed limitation reduces power demand, and current limitation prevents overload.

[0099] Linked with DCDC output voltage monitoring: If the DCDC output voltage drops (<564V) due to excessive current, the automatic pre-charge logic will be triggered to ensure stable control power supply.

[0100] ③Fault mitigation mechanism:

[0101] During the current limiting process, emergency stop is not triggered, only power output is limited, to avoid the locomotive stagnating in dangerous areas (such as slopes and curves) due to current limiting, taking into account both safety and operational continuity.

[0102] Examples of actual application scenarios:

[0103] Scenario 1: Current overload when the tram is climbing a slope:

[0104] When climbing a slope, the motor's required torque increases, and the discharge current rises to 160A → triggering the first-level current limit, maintaining the current speed for 10 seconds → If the slope is gentle, the current may drop back to 140A, releasing the current limit; If the slope is steep, the current continues to 160A → Entering the second-level current limit, the current is limited to 120A, and the tram climbs slowly at a lower acceleration to avoid over-discharge of the battery.

[0105] Scenario 2: Battery aging causes internal resistance to increase:

[0106] During normal operation, the discharge current of an aging battery may continue to be ≥150A, triggering the secondary current limit. The current is limited to a safe value calculated by the BMS (such as 100A). At this time, the tram speed may decrease, but it can still maintain operation, and at the same time remind maintenance personnel to replace the battery.

[0107] Through the hierarchical control strategy of "buffer-hard limit", transportation efficiency is maximized while protecting battery safety, breaking through the "one-size-fits-all" defect of traditional current limiting logic (i.e., immediate shutdown when the current exceeds the threshold).

[0108] Dynamically adapt to changes in working conditions: intelligently adjust the current limit level according to the current duration to avoid false operation;

[0109] Multi-parameter collaborative control: Combines the real-time battery status (BMS data) with driving conditions (speed, slope) to achieve refined current limiting; Balances safety and efficiency: Protects the battery without interrupting driving, suitable for continuous transportation needs in underground unmanned driving scenarios.

[0110] A switching strategy of "coasting mode takes precedence over battery input" is proposed to avoid high-current discharge of the battery at the moment of power failure (the traditional solution directly inputs the battery pack, and the current surge can reach more than 300A). Combined with the current limiting algorithm, the discharge current is controlled within 120A, extending the battery life by 40%.

[0111] In some specific embodiments of the present application, remote speed control: ramp function and adaptive adjustment are also included.

[0112] Specifically include: ramp acceleration parameters:

[0113] Slope k = 0.1 m / s 2 (It takes about 20 seconds to increase the coasting speed to 7 km / h). The speed setting formula is:

[0114] v(t)=v start +k·t(t≤t max );

[0115] in:

[0116] v start is the speed at the end of the slide,

[0117] t max To reach the target speed, ensure the acceleration is ≤ 0.1m / s2 to avoid DCDC overcurrent. Adaptive target value setting:

[0118] When the speed decreases during taxiing, the target speed is calculated according to the following formula:

[0119] v target =v actual +Δv·(1-e-t / τ );

[0120] Where Δv = 1 km / h, τ = 5 s, and exponential smoothing is used to avoid sudden changes in control values.

[0121] Traditional remote control uses a fixed target speed, which can easily cause high DC / DC current output (peaks up to 200A) due to speed deviation when power is restored after a power outage. This method uses ramped acceleration and adaptive reference speed to control current fluctuations within ±30A, eliminating the impact problem during power switching.

[0122] It should be noted here that the power supply architecture is an independent power supply circuit.

[0123] The power supply of the hydraulic oil pump inverter and DCDC converter is decoupled from the pantograph DC bus and instead independently supplied by the battery pack, forming a dual-circuit architecture with "separation of power supply and control power supply".

[0124] In traditional solutions, a loss of power to the pantograph results in a control power outage. This approach, however, utilizes a battery pack for independent power supply, ensuring the hydraulic brake system and control unit continue to function normally during a power outage, achieving "power outage without interruption of control." Fast-acting fuses and solid-state relays are used in hardware to isolate the power supply, while power switching logic is incorporated into the software to ensure interference-free switching between the two power sources. This architecture is a first for dual-powered mining trams.

[0125] The intelligent optimization of emergency stop protection is signal strength judgment and double protection.

[0126] Wireless signal strength (<40% and lasting for 2s) is introduced as the emergency stop trigger condition, and anti-interference emergency stop logic is constructed through hardware dual protection and signal filtering algorithm.

[0127] Existing technologies rely solely on hardware failure signals to trigger emergency stops, without considering the impact of wireless communication quality on autonomous driving. This method uses signal strength as a safety threshold, triggering an emergency stop in advance when communication quality deteriorates to a critical value, thereby preventing loss of control due to command loss.

[0128] The safety relay's dual control circuit (positive control + negative feedback) and contact monitoring increase the reliability of the emergency stop signal to 99.99%, and reduce the false trigger rate from 0.5 times / day to 0.05 times / month.

[0129] Automatic coordination of pre-charging and switching: multi-parameter linkage control:

[0130] Based on multiple parameters such as pantograph voltage, battery pack voltage, and DCDC output, a dynamic pre-charging strategy and a "coasting-to-battery" graded switching mechanism are designed to achieve automatic recovery of the power system after power outages.

[0131] Traditional pre-charging requires manual closing of the pre-charging switch. This method achieves full automation through MECU logic control, eliminating the need for manual intervention in the pre-charging process and adapting to unmanned driving scenarios (see the advantages of "unmanned driving intelligent operation" in the invention content). The "slip mode priority" design in the switching mechanism prevents the battery pack from being directly put into use at the moment of power failure, reducing the switching current impact from 300A to below 80A, thereby protecting the battery pack life (the existing technology does not have a hierarchical switching strategy, see the problem of "battery over-discharge" in the background technology).

[0132] Through this application, the hardware improvement and software and control logic upgrade will solve the emergency stop problem of dual-powered trams in abnormal power outage areas and achieve non-stop coasting; improve the running smoothness and transportation efficiency of the locomotive, and reduce the loss of equipment caused by frequent starting and stopping.

[0133] Specifically including: hardware improvements.

[0134] Among them, hardware improvements include: circuit architecture optimization, emergency stop protection logic and safety relay circuit optimization, and hydraulic system control logic optimization.

[0135] Specifically, the circuit architecture is optimized as follows:

[0136] Change the power source of the hydraulic oil pump inverter and 750VDC to 24VDC direct converter from the common DC bus to the battery pack.

[0137] Even if the DC bus loses power momentarily, the hydraulic system and control power supply can still operate normally, avoiding emergency stops of the locomotive due to power interruption and ensuring the continuous operation of basic functions.

[0138] Specifically, the emergency stop protection logic and safety relay circuit are optimized as follows:

[0139] Access the wireless signal strength judgment in the ATO command (lower than 40% and lasting for 2 seconds to trigger an emergency stop);

[0140] Filter signals such as emergency stop commands and heartbeat data to prevent misjudgment caused by electromagnetic interference;

[0141] The MECU controller directly drives the safety relay and adds the coil negative pole and signal collection point to achieve double protection.

[0142] Reduce false emergency stops caused by signal interference or momentary power outages, improve the accuracy and reliability of emergency stop control, and reduce the frequency of unnecessary stops.

[0143] Specifically, the hydraulic system control logic is optimized as follows:

[0144] Configure an accumulator, set the system pressure to the normal range (80-150bar), and combine the hydraulic pressure to determine the impact of the inverter fault signal;

[0145] In case of inverter fault, 10 seconds of reset attempt is allowed, with coasting mode taking priority, and pressure protection is not triggered immediately during fault.

[0146] Reduce false fault alarms caused by momentary power outages in the hydraulic system, ensure that braking performance is not affected, and avoid parking caused by hydraulic failures.

[0147] Among them, the software and control logic upgrades include: automatic pre-charging function of the motor controller, DCDC self-reset mechanism, pantograph and battery pack switching optimization, current limiting and speed control strategy, current limiting and speed control strategy, communication protocol and data interaction optimization, and software and hardware collaborative improvement.

[0148] Specifically, the automatic pre-charging function of the motor controller includes:

[0149] Detect switch signals and operating modes, and automatically control pre-charge circuit contactors and resistor connections;

[0150] The pre-charge condition is determined based on parameters such as voltage and speed, so that the motor controller can automatically reset to the ready mode after power failure.

[0151] The motor controller can be restored to working status without manual intervention, shortening the restart time after power failure and ensuring the continuous operation of the locomotive.

[0152] Specifically, the DCDC self-reset mechanism includes:

[0153] Send software reset instructions through the J1939 protocol. If failure occurs, restore DCDC operation through hardware reset (control power supply re-powered on).

[0154] Automatically repair instantaneous failures of the DCDC unit to avoid shutdown of the entire vehicle equipment due to DCDC power outages.

[0155] Specifically, the optimization of pantograph and battery pack switching includes:

[0156] When the pantograph loses power abnormally in the pantograph raising state, it will first enter the coasting mode, and the battery pack will only supply control power to avoid high current shock;

[0157] Detect pantograph voltage (below 600V is considered abnormal) and encoder position to accurately determine the pantograph status.

[0158] Prevent the battery pack from over-discharging, ensure a smooth switching process, and avoid damage to the equipment due to instantaneous current shock during power switching.

[0159] Specifically, the current limiting and speed control strategies include:

[0160] The speed limit in local / remote mode is 7km / h, the motor current is limited to 120A, and acceleration is canceled when the battery discharge current reaches 150A;

[0161] In remote mode, the target speed is given according to the actual speed ramp at the end of the coasting to avoid control value deviation.

[0162] Prevent battery over-discharge, ensure smooth locomotive speed-up, and avoid DCDC high current output or equipment failure due to current mutation.

[0163] Specifically, the optimization of communication protocols and data interaction includes:

[0164] ATO and MECU are programmed using the J1939 protocol to achieve real-time interaction of control instructions and status information.

[0165] Improve system response speed and data transmission stability to ensure accurate execution of control commands in remote unmanned driving mode.

[0166] Specifically, the collaborative improvements in software and hardware include:

[0167] Combining hardware circuit reconstruction (such as independent power supply) and software logic upgrade (such as automatic pre-charging and fault filtering), a continuous operation plan for abnormal power outage areas is formed.

[0168] Solve the emergency stop problem of dual-powered trams in abnormal power outage areas and achieve non-stop coasting;

[0169] Improve the running smoothness and transportation efficiency of locomotives and reduce the loss of equipment caused by frequent starting and stopping;

[0170] Provide reusable technical solutions for the design of similar mine trams.

[0171] The above describes some specific embodiments of the present application. It should be understood that the present application is not limited to the specific embodiments described above, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the substantive content of the present application. The above preferred features may be used in any combination as long as they do not conflict with each other.

Claims

1. A method for uninterrupted driving of an underground dual-powered tram through a power outage area, which is applied to an underground tram in a pantograph + battery pack dual-power mode, and the tram is in a remote unmanned operation state, and is characterized by: By improving the hardware circuit and upgrading the software function, the tram can continue to glide in the abnormal power outage area. The specific steps include: Optimize the tram's circuit architecture and switch the power supply circuits for the hydraulic oil pump inverter and 750VDC to 24VDC converter to be drawn from the battery pack; Optimize the emergency stop protection logic, set the automatic reset function of the safety relay circuit, and integrate the wireless communication signal strength judgment into the emergency stop control to filter the emergency stop command and other signals; Automatically precharge the motor controller through MECU logic control, and adjust the precharge strategy based on the pantograph voltage and battery pack voltage parameters; Optimize the switching mechanism between the pantograph and the battery pack, and give priority to entering the coasting mode in the event of an abnormal power outage.

2. The method for uninterrupted driving of an underground dual-powered electric vehicle through a power outage area according to claim 1, characterized in that: Emergency stop protection logic optimization specifically includes: The wireless communication signal strength collected by ATO is lower than 40% and lasts for 2 seconds as the emergency stop trigger condition, and jump filtering is adopted for the emergency stop command and heartbeat data signal, and double protection is implemented through the positive and negative poles of the coil of the safety relay and the signal collection point.

3. The method for uninterrupted driving of an underground dual-powered electric vehicle through a power outage area according to claim 1, characterized in that: The MECU's processing of fault signals includes: The oil pump inverter fault signal and the direct current converter fault signal are de-jittered and filtered, and the hydraulic system pressure of 80-150bar is used as the fault judgment factor. The inverter is allowed to reset through the CAN bus within 10 seconds. If the reset is invalid, a fault signal is output.

4. The method for uninterrupted driving of an underground dual-powered electric vehicle through a power outage area according to claim 1, characterized in that: The automatic priming steps include: After detecting the key switch signal and the remote ATO mode signal is enabled, the pre-charge circuit contactor is attracted; When the pantograph voltage is lower than 600V and the battery pack voltage is higher than 500V, the pre-charging resistor is connected and the drive contactor is disconnected; The system switches to coasting control mode according to the driving speed. When the DCDC output voltage reaches 564V and the motor controller voltage reaches 500V, the pre-charge resistor is isolated and the drive contactor is turned on.

5. The method for uninterrupted driving of an underground dual-powered electric vehicle through a power outage area according to claim 1, characterized in that: The switching mechanism between the pantograph and the battery pack includes: The pantograph status is determined by the push rod motor encoder data. When the pantograph voltage is lower than 600V, it is determined as an abnormal power outage and the vehicle enters coasting mode. During the coasting stage, the battery pack only supplies power to the on-board control power supply. If the DCDC does not work normally, the battery pack will be put into the motor controller drive circuit.

6. The method for uninterrupted driving of an underground dual-powered electric vehicle through a power outage area according to claim 1, characterized in that: Also includes current limiting control for battery pack discharge: In long-range mode, the speed is forcibly limited to 7 km / h, and the maximum current of the motor controller is limited to 120A. When the discharge current reaches 150A, acceleration is canceled and the vehicle switches to a constant speed for 10 seconds. If the current still exceeds the limit during the second acceleration, the vehicle enters current limiting mode with the battery pack current as the maximum limit.

7. The method for uninterrupted driving of an underground dual-powered electric vehicle through a power outage area according to claim 1, characterized in that: Speed ​​control in remote mode includes: If the speed drops during coasting due to an abnormal power outage, the remote control target value is given with reference to the actual speed; After the coasting mode is switched to the battery pack mode, the actual speed at the end of the coasting is used as the starting point and the speed is gradually increased to the target speed in a ramp manner.

8. The method for uninterrupted driving of an underground dual-powered electric vehicle through a power outage area according to claim 1, characterized in that: The ATO control unit and MECU control unit are programmed through the IQUNdesigne platform and use the J1939 communication protocol to exchange data with the DCDC, motor controller, and inverter for control command transmission and status information collection.

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