A dual wheel mill green power system energy management strategy

Abstract

The application discloses a kind of double-wheel milling green power system energy management strategy, belong to engineering machinery field, to solve the problems, such as power weakness, energy consumption soaring, thermal runaway and electrical safety hazard, etc., existing in prior art under plateau extreme environment, the strategy is by environment parameter dynamic correction engine output characteristic, limit its working point in green economic operation area;Adopt peak clipping and electric assistance and mixed power collaborative logic, make up plateau engine transient response deficiency;Based on predictive model, realize active heat dissipation control, and execute differentiated thermal management to energy storage system;While realizing feedback energy grading storage, operation object hardness self-adaptive identification, stuck solution and plateau electrical safety protection.The application deeply adapts plateau low air pressure, large temperature difference and other extreme conditions, effectively avoids engine black smoke and system thermal protection shutdown, significantly improves the fuel economy, operation safety and operation continuity of double-wheel milling in plateau area.

Description

Technical Field

[0001] This invention relates to the field of engineering machinery, and specifically to an energy management strategy for a dual-wheel milling green power system. Background Technology

[0002] Twin-wheel milling machines, used for constructing diaphragm walls, are widely applied in major engineering projects such as water conservancy and hydropower, urban rail transit, and deep foundation pit support. An increasing number of foundation engineering projects are located in extreme environments above 3000 meters in altitude. In these areas, the power system of twin-wheel milling machines faces unprecedented challenges: for every 1000 meters increase in altitude, the rated power of the diesel engine decreases by approximately 8%-12%, while the reduced air density leads to a significant decrease in the cooling airflow provided by the cooling fan, resulting in a sharp decline in radiator heat exchange efficiency.

[0003] In existing technologies, the energy management strategies of dual-wheel milling green power systems are mainly designed for plains environments, and their logic is to optimize the engine under the premise that the full power output capability is sufficient. However, when these strategies are applied to high-altitude environments, a series of serious problems arise: First, there is the problem of engine external characteristic derating. If the strategy still requests high power according to the plains MAP, it will lead to severe black smoke from the engine and a sharp increase in heat load. Second, there is the problem of low heat dissipation efficiency. The traditional constant-temperature fan start strategy will cause the temperature to rise too quickly, triggering the system's thermal protection shutdown. Third, there is the problem of energy storage system safety. The strong ultraviolet radiation and low heat dissipation efficiency at high altitudes can easily cause the lithium battery temperature to exceed the safety threshold, leading to thermal runaway. At night, the extremely low temperatures will cause the battery's internal resistance to increase sharply, making it unable to discharge. Fourth, there is the problem of electrical safety. As the altitude increases, the air becomes thinner, and the breakdown voltage of electrical gaps drops significantly, making it easy to generate arcing and creepage phenomena.

[0004] Therefore, there is an urgent need for an energy management strategy for a dual-wheel milling green power system that can be deeply optimized for the special characteristics of the plateau environment, in order to solve the problems of weak power, soaring energy consumption, thermal runaway and even system shutdown when existing technologies are applied in plateau areas. Summary of the Invention

[0005] To address the challenges posed by existing technologies in extreme environments such as low air pressure, low oxygen levels, large temperature differences, and low heat dissipation efficiency in high-altitude regions, this application provides an energy management strategy for a dual-wheel milling green power system.

[0006] To achieve the above objectives, the technical solution adopted in this application is: an energy management strategy for a dual-wheel milling green power system, comprising the following steps:

[0007] S101: Based on the data collected in real time by the environmental parameter sensing device, the output characteristics of the engine under the current environmental conditions are dynamically corrected, and the engine operating point is limited to the green economic operating zone defined by the excess air coefficient and fuel economy index through the optimization algorithm.

[0008] S102: Real-time monitoring of the state of charge of the energy storage system; under steady-state conditions, controlling the engine to operate at the optimal economic operating point and recovering excess power; under conditions of instantaneous high torque, controlling the drive motor to intervene instantaneously to provide peak torque assistance.

[0009] S103: Based on real-time operating parameters and environmental conditions, a predictive model is used to predict the trend of system heat load changes, adjust the operating parameters of the cooling system in advance, and incorporate the parasitic power consumption of the heat dissipation system into the global energy optimization target;

[0010] S104: Implement differentiated thermal management strategies based on the temperature of the energy storage system. At high temperatures, limit the charge / discharge rate and enhance cooling; at low temperatures, preheat and limit the electric auxiliary power.

[0011] S105: Under energy recovery conditions, the drive motor is switched to power generation mode, the feedback energy is stored in stages according to the power characteristics of the energy storage medium, and a composite filtering algorithm is used to smooth the transient feedback power.

[0012] S106: By analyzing the fluctuation characteristics of the electrical parameters of the drive system and the load parameters of the working device, combined with the wear status of the working tools, the hardness level of the working object can be identified in real time, and the operating parameters of the working device can be dynamically adjusted.

[0013] S107: When the working device is stuck, it enters the trouble-relief mode, which allows the drive motor to be overloaded for a short time and calls the limit discharge power of the energy storage system. The trouble-relief process is controlled by a preset safety constraint strategy.

[0014] S108: When electrical safety parameters or environmental condition parameters are lower than their respective preset thresholds, actively reduce the upper limit of DC bus voltage and the switching frequency of power devices to suppress discharge phenomena.

[0015] Further, in step S1, the environmental parameter sensing device includes an atmospheric pressure sensor and an oxygen sensor; the dynamic correction of engine output characteristics includes:

[0016] The extreme output external characteristic curve of the engine is reconstructed in real time using an altitude-oxygen content correction model. The correction formula for the extreme output external characteristic curve is as follows:

[0017] ;

[0018] in, This represents the actual allowable output power limit at an altitude of h. The nominal power is at the reference altitude; k is the altitude derating factor; h is the actual installation altitude. Used as a reference elevation;

[0019] The boundary of the green economic operating zone is jointly defined by the excess air coefficient λ and the brake ratio fuel consumption rate BSFC. When the oxygen sensor detects that the oxygen concentration is lower than the set threshold, the range of the green economic operating zone is narrowed, and the engine is forced to reduce its output power.

[0020] Furthermore, in step S102, the control strategy under steady-state conditions includes peak shaving and valley filling logic:

[0021] When the actual load power Power output below the engine's optimal economic operating point At that time, the engine was still running, with excess power. - The energy storage system is charged by a generator;

[0022] The control strategy under instantaneous high torque conditions includes electric power assist logic:

[0023] When the actual load power Exceeding the engine's environmentally modified power limit At that time, the drive motor momentarily intervenes to provide peak torque assistance, and the power provided by the drive motor is Meanwhile, the engine maintains its position. The purpose is to avoid entering the enrichment supply area.

[0024] Furthermore, it also includes steps to extend intelligent start-stop and pure electric drive strategies:

[0025] When the twin-wheel milling machine is in a low-load or zero-load condition during drilling and mud system operation, the system is switched to pure electric drive mode, the engine is turned off, and the energy storage system provides power independently.

[0026] When the state of charge (SOC) of the energy storage system is lower than the set threshold or the load power exceeds the limit output of the energy storage system, the engine is restarted.

[0027] Further, in step S103, the prediction model is:

[0028] ;

[0029] in, For cutting torque, For engine load rate, This is the current altitude;

[0030] when When the set percentage of the radiator's maximum heat dissipation capacity at the current altitude is exceeded, the fan speed is increased to the maximum value in advance, and the cooling water pump flow rate is increased at the same time; within the range allowed by thermal balance, the fan speed is reduced to reduce parasitic power consumption, and the saved power is used for cutting operations or charging of energy storage systems.

[0031] Further, in step S104, the differentiated thermal management strategy includes:

[0032] When the temperature of the energy storage system exceeds the first threshold When the temperature of the energy storage system exceeds the second threshold, the charge / discharge rate is limited to a safe value; when the temperature of the energy storage system exceeds the second threshold... At this time, the maximum power is allowed to drop to the minimum value, while the liquid cooling system is forced to start;

[0033] When the energy storage system temperature is below a set threshold Preheating is performed using a stalled motor heater or a PTC heater before the energy storage system reaches its optimal operating temperature. Previously, the electric auxiliary power was limited to a set percentage of the rated value.

[0034] Further, in step S105, the tiered storage of feedback energy according to the power characteristics of the energy storage medium includes:

[0035] Transient high-power feedback energy is preferentially stored in power-type energy storage medium supercapacitors, while continuous low-power feedback energy is stored in energy-type energy storage medium power batteries;

[0036] The composite filtering algorithm includes: using a low-pass filter to smooth the feedback power; the filter time constant is dynamically adjusted according to the altitude. The higher the altitude, the lower the insulation withstand voltage margin, and the larger the filter time constant, so as to reduce peaks to a greater extent.

[0037] The maximum value of the feedback power is limited to ,in This is the altitude correction factor, which decreases as altitude increases.

[0038] Furthermore, in step S106, the electrical parameters of the drive system include the drive motor current fluctuation rate. The load parameters of the working device include torque variability. ;pass and The hardness level of the work object is identified by combining the wear status of the work tools, and the hardness of the work object is divided into four levels: soft soil, medium hard rock, hard rock, and boulder. The milling wheel speed and feed rate are adjusted according to the identification results: for each increase in the hardness of the work object, the milling wheel speed and feed rate are reduced by a set percentage, and electric assist torque compensation is added.

[0039] Further, in step S107, the detection condition for the work device jamming is: the change in the torque of the work device within a set time exceeds a first threshold, and the rotational speed of the work device is lower than a second threshold.

[0040] The trouble-solving mode includes: removing the rated power limit of the drive motor, calling the limit discharge power of the energy storage system, and coordinating with the engine to output transient trouble-solving peak torque;

[0041] The preset safety constraint strategy includes: the duration of the escape mode does not exceed a set number of seconds, and the normal restrictions are restored immediately after the escape is successful, in order to protect the mechanical and electrical systems.

[0042] Further, in step S108, the electrical safety parameters include the DC bus-to-ground insulation resistance, and the environmental condition parameters include ambient air pressure; when the insulation resistance is lower than the altitude-corrected safety threshold... Or when the ambient air pressure is lower than the set threshold, the upper limit of the DC bus voltage will be reduced from... Reduce to ,in This is the altitude voltage derating factor, which decreases with increasing altitude; simultaneously, reducing the switching frequency of power devices reduces... It suppresses discharge phenomena caused by electromagnetic interference and high-frequency harmonics.

[0043] Beneficial effects:

[0044] 1. By collecting data in real time through environmental parameter sensors and dynamically correcting engine output characteristics, the engine operating point is limited to the green and economical operating zone defined by the excess air coefficient and fuel economy indicators. This effectively avoids the problems of black smoke and a sharp increase in heat load caused by the engine in the hypoxic environment of high altitude, and significantly improves the engine's operating efficiency and emission levels in the high-altitude environment.

[0045] 2. By monitoring the state of charge of the energy storage system in real time and implementing a hybrid power strategy of supplementing diesel with electricity, peak shaving and valley filling are achieved under steady-state conditions, and electric assistance is achieved under instantaneous high torque conditions. The instantaneous torque characteristics of the motor are fully utilized to compensate for the insufficient transient response of the engine in the hypoxic environment of the plateau, thus avoiding a significant drop in engine speed and black smoke emissions.

[0046] 3. By adopting an active heat dissipation allocation strategy based on a predictive model, thermal management is upgraded from passive response to active prediction. The operating parameters of the cooling system are adjusted in advance, and the parasitic power consumption of the heat dissipation system is incorporated into the global energy optimization target. This effectively solves the problem of system thermal protection shutdown caused by low heat dissipation efficiency under the low air density of high altitudes, while optimizing the overall energy utilization efficiency. Through differentiated energy storage system thermal management strategies, the charge and discharge rate is limited and cooling is enhanced at high temperatures, while preheating and electric auxiliary power are limited at low temperatures. This effectively avoids thermal runaway and low-temperature failure of the energy storage system under extreme temperature difference conditions in high-altitude environments, ensuring the safe operation of the energy storage system in high-altitude environments. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a flowchart illustrating the energy management strategy of the dual-wheel milling green power system according to an embodiment of this application. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0050] Example

[0051] Please refer to Figure 1 This embodiment provides an energy management strategy for a dual-wheel milling green power system, including the following steps:

[0052] S101: Based on the data collected in real time by the environmental parameter sensing device, the output characteristics of the engine under the current environmental conditions are dynamically corrected, and the engine operating point is limited to the green economic operating zone defined by the excess air coefficient and fuel economy index through the optimization algorithm.

[0053] In this step, environmental parameter sensors first collect real-time environmental parameters that directly affect the engine's combustion efficiency and output characteristics. Based on the collected environmental data, the engine's output characteristic curve under the current environmental conditions is dynamically corrected to eliminate the adverse effects of environmental factors on engine output and ensure that the engine's output characteristics match the current environment. Subsequently, an optimization algorithm is used to screen and restrict the engine's operating point, forcibly constraining it within a green and economical operating zone defined by the excess air coefficient and fuel economy indicators. The excess air coefficient determines the completeness of engine combustion, while the fuel economy indicators determine the engine's energy consumption level. The combination of these two factors achieves the green operation goal of low emissions and low fuel consumption, while ensuring that the engine output meets the system's basic power requirements.

[0054] S102: Real-time monitoring of the state of charge of the energy storage system; under steady-state conditions, controlling the engine to operate at the optimal economic operating point and recovering excess power; under conditions of instantaneous high torque, controlling the drive motor to intervene instantaneously to provide peak torque assistance.

[0055] In this step, the energy storage system's state of charge (SOC) is monitored in real time using its built-in detection module. This allows for precise understanding of the system's remaining power and charging / discharging capabilities, providing a basis for power allocation. Differentiated control is implemented for different operating conditions: Under steady-state conditions such as steady-state cutting, the system load demand is stable. In this case, the engine is controlled to operate at a preset optimal economic operating point, which represents the state with the lowest fuel consumption and highest efficiency. When the engine output power exceeds the actual load demand and the energy storage system's SOC is below a first preset threshold, the excess power is guided to the energy storage system for charging, achieving energy recovery and storage, and avoiding energy waste. Under conditions of instantaneous high torque, the engine's response speed is slow and it cannot quickly provide peak torque. In this case, the drive motor is controlled to intervene instantaneously, utilizing the motor's advantages of fast response and high peak torque to supplement the engine's insufficient torque. This ensures that the system can smoothly cope with instantaneous load impacts, avoid engine overload and sudden speed drops, and ensure operational continuity.

[0056] S103: Based on real-time operating parameters and environmental conditions, a predictive model is used to predict the trend of system heat load changes, adjust the operating parameters of the cooling system in advance, and incorporate the parasitic power consumption of the heat dissipation system into the global energy optimization target;

[0057] In this step, real-time data is collected on the system's operating parameters and environmental conditions. These parameters are directly related to the heat load generated by various system components such as the engine, motor, and controller. A pre-set prediction model is used to predict the heat load change trend of the system in the next 10-30 seconds based on the collected real-time parameters, enabling advance prediction of heat load. Based on the prediction results, the operating parameters of the cooling system are adjusted in advance to avoid overheating of components due to insufficient cooling when the heat load increases suddenly, or excessive operation of the cooling system causing energy waste when the heat load is low. At the same time, the parasitic power consumption of the heat dissipation system is incorporated into the global energy optimization objective. Under the premise of ensuring that core components such as the engine, motor, controller, and battery are in thermal equilibrium, the cooling fan speed and cooling water pump flow rate are reduced as much as possible to save energy to the maximum extent and improve the overall energy utilization efficiency of the system.

[0058] S104: Implement differentiated thermal management strategies based on the temperature of the energy storage system. At high temperatures, limit the charge / discharge rate and enhance cooling; at low temperatures, preheat and limit the electric auxiliary power.

[0059] In this step, the temperature is monitored in real time by a temperature sensor. Different thermal management strategies are implemented based on the temperature range to ensure the safety and lifespan of the energy storage system, while avoiding the impact of abnormal temperatures on energy management performance. When the energy storage system temperature exceeds the preset high-temperature threshold, the charging and discharging performance of the energy storage system will decrease, and there will be safety hazards. At this time, its charging and discharging rate is limited to a certain percentage of the rated rate to reduce the charging and discharging intensity. At the same time, the cooling system is activated first for forced cooling. If it is in a special environment such as a high altitude, the cooling system flow rate needs to be increased accordingly based on the reduced heat dissipation efficiency to ensure the cooling effect. When in a low-temperature cold start scenario, and the energy storage system temperature is below the preset low-temperature threshold, the activity of the energy storage system decreases, and the charging and discharging capacity drops significantly. At this time, the energy storage system is preheated by methods such as motor no-load heating or PTC heating to improve its activity. Before the energy storage system temperature reaches the optimal operating temperature range of 25℃-40℃, the electric auxiliary power is limited to a certain percentage of the rated power, and high-current charging is prohibited to avoid irreversible damage to the energy storage system caused by forced charging and discharging at low temperatures.

[0060] S105: Under energy recovery conditions, the drive motor is switched to power generation mode, the feedback energy is stored in stages according to the power characteristics of the energy storage medium, and a composite filtering algorithm is used to smooth the transient feedback power.

[0061] In this step, when the system is in energy recovery conditions such as milling wheel lowering or vehicle emergency braking, the drive motor is switched to generator operation mode to convert the mechanical energy generated during operation into electrical energy, realizing energy recovery and reuse. Since different energy storage media have different power carrying characteristics and transient response speeds, the feedback energy is stored in stages according to the power characteristics of the energy storage media. High-power feedback energy is prioritized for storage in the supercapacitor to avoid damage to the power battery from instantaneous high power. The remaining energy is then stored in the power battery to achieve reasonable energy distribution. At the same time, a composite filtering algorithm combining moving average filtering and amplitude limiting filtering is used to optimize the transient feedback power. A reasonable filtering time constant is set to smooth the fluctuation of transient power and prevent the instantaneous extremely high feedback voltage from breaking down electrical components with degraded insulation performance under special environments such as low air pressure, thus ensuring the safety of the electrical system.

[0062] S106: By analyzing the fluctuation characteristics of the electrical parameters of the drive system and the load parameters of the working device, combined with the wear status of the working tools, the hardness level of the working object can be identified in real time, and the operating parameters of the working device can be dynamically adjusted.

[0063] In this step, the electrical parameters of the drive system and the load parameters of the working device are collected in real time. The fluctuation characteristics of these parameters are directly related to the hardness of the workpiece. The higher the hardness of the formation, the greater the load on the milling wheel, and the more drastic the fluctuations in torque and motor current. At the same time, compensation is made in combination with the wear status of the working tool. Through a preset recognition algorithm, the hardness level of the current cutting formation is determined in real time. Based on the identified hardness level, the operating parameters of the working device are dynamically adjusted: when an extremely hard formation is identified, the feed rate is actively reduced and the output torque is increased to prevent the system from falling into a deep overload state due to excessive load; when the formation hardness is low, the feed rate can be appropriately increased to improve work efficiency and achieve work control that balances efficiency and load, while reducing energy waste and tool wear.

[0064] S107: When the working device is stuck, it enters the trouble-relief mode, which allows the drive motor to be overloaded for a short time and calls the limit discharge power of the energy storage system. The trouble-relief process is controlled by a preset safety constraint strategy.

[0065] In this step, the operating status of the milling wheel is monitored in real time by sensors. When the milling wheel torque suddenly increases to a certain percentage of the rated torque and the speed drops to zero for a certain period of time, it is determined that the working device is stuck. At this time, the system automatically enters the unblocking mode. To achieve rapid unblocking, the drive motor is allowed to be overloaded to a certain percentage of the rated power for a short time. At the same time, the limit discharge power of the energy storage system is called up, combined with the output power of the diesel engine, to provide the transient unblocking peak torque to overcome the stuck resistance. To ensure system safety, the unblocking process is controlled by preset safety constraint strategies, such as limiting the duration of the unblocking peak torque to 3-5 seconds, allowing a maximum of 2 consecutive energy bursts in a single unblocking cycle, and the interval between the two energy bursts is not less than 30 seconds to avoid damage to the engine, motor, and energy storage system caused by prolonged overload. After successful unblocking, the system immediately restores the normal power limit and returns to the normal energy management mode.

[0066] S8: When electrical safety parameters or environmental condition parameters are lower than their respective preset thresholds, actively reduce the upper limit of DC bus voltage and the switching frequency of power devices to suppress discharge phenomena.

[0067] In this step, the electrical safety parameters and environmental condition parameters of the system are monitored in real time, and their respective preset safety thresholds are set. When the system insulation resistance is detected to drop to a dangerous threshold, or the ambient air pressure is lower than the preset threshold, the insulation performance of the electrical system will decrease, making it prone to phenomena such as corona discharge, which threatens system safety. At this time, the system actively takes protective measures: reducing the upper limit of the DC bus voltage by 10%-15% to reduce the voltage impact on the insulation layer, and reducing the switching frequency of the power devices by 20%-30% to suppress the generation of electromagnetic interference and high-frequency harmonics, thereby suppressing the corona discharge phenomenon, ensuring the safe and stable operation of the electrical system in complex environments, and avoiding the impact of electrical faults on the operation of the entire power system.

[0068] Further, in step S101 above, the environmental parameter sensing device includes an atmospheric pressure sensor and an oxygen sensor; the dynamic correction of engine output characteristics includes:

[0069] The extreme output external characteristic curve of the engine is reconstructed in real time using an altitude-oxygen content correction model. The correction formula for the extreme output external characteristic curve is as follows:

[0070] ;

[0071] in, This represents the actual allowable output power limit at an altitude of h. The nominal power is at the reference altitude; k is the altitude derating factor; h is the actual installation altitude. Used as a reference elevation;

[0072] Using this formula, the system can dynamically calculate the engine's maximum output power at the current altitude based on real-time collected altitude data, reconstruct the maximum output external characteristic curve, eliminate the adverse effects of altitude changes, especially the low air pressure environment at high altitudes, on engine output, and ensure that the engine output meets the system's power requirements without causing power overload or incomplete combustion due to excessive altitude.

[0073] The boundary of the green economic operating zone is jointly defined by the excess air coefficient λ and the brake ratio fuel consumption rate BSFC. When the oxygen sensor detects that the oxygen concentration is lower than the set threshold, the range of the green economic operating zone is narrowed, and the engine is forced to reduce its output power.

[0074] In the green economic operating zone control phase, the boundary of the green economic operating zone is clearly defined by the excess air coefficient λ and the brake ratio fuel consumption rate (BSFC). These two factors form a dual constraint to ensure that the engine operates within a low-emission, low-fuel-consumption range. The excess air coefficient λ determines the completeness of engine combustion; a reasonable λ value enables oxygen-rich combustion, reducing emissions of pollutants such as carbon monoxide and hydrocarbons. The brake ratio fuel consumption rate (BSFC) directly reflects the engine's fuel economy; the lower the BSFC value, the lower the engine's fuel consumption and the higher its energy utilization efficiency. The combination of these two factors defines the engine's green economic operating zone, and the system uses an optimization algorithm to forcibly constrain the engine's operating point within this range. Meanwhile, the system monitors the oxygen concentration in the environment and engine intake air in real time through oxygen sensors. When the oxygen sensor detects that the oxygen concentration is lower than the set threshold, it indicates that the current oxygen supply is insufficient. If the original green and economical operating range is maintained, it will lead to incomplete combustion of the engine, increased fuel consumption, and excessive pollutant emissions. At this time, the system automatically shrinks the green and economical operating range and forces the engine to reduce its output power and reduce the amount of fuel injection to ensure that the engine can still maintain a relatively complete combustion state when the oxygen supply is insufficient. This balances green environmental protection and operational stability, and avoids engine failure or performance degradation due to lack of oxygen.

[0075] Furthermore, in step S102, the control strategy under steady-state conditions includes peak shaving and valley filling logic:

[0076] When the actual load power Power output below the engine's optimal economic operating point At that time, the engine was still running, with excess power. - The energy storage system is charged by a generator;

[0077] The control strategy under instantaneous high torque conditions includes electric power assist logic:

[0078] When the actual load power Exceeding the engine's environmentally modified power limit At that time, the drive motor momentarily intervenes to provide peak torque assistance, and the power provided by the drive motor is Meanwhile, the engine maintains its position. The purpose is to avoid entering the enrichment supply area.

[0079] The essence of peak shaving and valley filling logic is to use the energy buffering effect of the energy storage system to force the engine's operating point to be locked at the optimal economic operating point. This prevents the engine from entering an inefficient operating range due to load fluctuations. The engine's optimal economic operating point. It is the only operating point on its universal characteristic curve where the fuel consumption (g / kW・h) is the lowest. It is usually located in the low to medium speed and medium to high load range, where the engine has the highest thermal efficiency and the best fuel economy.

[0080] When the system detects the actual load < At that time, the engine is not allowed to reduce its output power, but is forced to maintain it at a certain level. Run; calculate excess power: ΔP = - The drive motor automatically switches to generator mode, converting ΔP power into electrical energy, which is then input into the energy storage system for charging.

[0081] The prerequisite is that the state of charge (SOC) of the energy storage system is below a first preset threshold to avoid overcharging; when the SOC reaches the first preset threshold, the system will appropriately reduce the engine power, but still try to keep it operating near the optimal economic zone.

[0082] Specifically, the above-mentioned electric power assist logic utilizes the characteristics of the electric motor's fast instantaneous response and high peak torque to ensure that the engine reaches its environmentally corrected maximum power. At the same time, it provides instantaneous power compensation to prevent the engine from entering the enriched fuel injection zone. The engine's maximum power after environmental correction. It is calculated using the altitude-oxygen content correction model in step S101, and represents the maximum power that the engine can maintain under current conditions with oxygen-rich combustion (excess air coefficient λ≥1.1).

[0083] During the triggering conditions and execution process, when the system detects the actual load... > At that time, the engine is not allowed to continue increasing the fuel injection quantity, but is forced to maintain it at a certain level. Run; calculate the power difference: ΔP = - The drive motor reaches peak torque within 100ms, providing ΔP power to work with the engine to meet load requirements.

[0084] When the actual load falls back to When the motor stops, it will automatically exit the power assist mode and return to standby mode.

[0085] It should be noted that if the engine output power exceeds This necessitates increasing the fuel injection quantity, resulting in an excess air coefficient λ < 1, which enters the enriched fuel supply zone, leading to the following serious consequences:

[0086] 1. Incomplete combustion of fuel increases fuel consumption by more than 30% and produces a large amount of black smoke.

[0087] 2. Emissions of carbon monoxide and hydrocarbons have increased dramatically, polluting the environment.

[0088] 3. The afterburning period is prolonged, the exhaust temperature rises significantly, the engine thermal load increases significantly, and the wear of components such as pistons and valves is accelerated.

[0089] 4. In severe cases, it can lead to fatal malfunctions such as piston top burning and cylinder scoring.

[0090] In actual use, the peak shaving and valley filling logic and the electric power assist logic do not operate independently, but form a closed-loop energy cycle system: under steady-state cutting conditions, the peak shaving and valley filling logic stores excess energy from the engine into the energy storage system; under instantaneous high torque conditions, the electric power assist logic releases the stored energy to provide power compensation; this energy storage and release cycle mechanism improves fuel economy and ensures power responsiveness; the system dynamically adjusts the trigger thresholds of the two logics according to the SOC state of the energy storage system to ensure energy supply and demand balance.

[0091] Furthermore, it also includes steps to extend intelligent start-stop and pure electric drive strategies:

[0092] When the dual-wheel milling machine is in a zero-load condition such as drilling or low-load operation of the mud system, the system is switched to pure electric drive mode, the engine is turned off, and the energy storage system supplies power alone.

[0093] When the state of charge (SOC) of the energy storage system is lower than the set threshold or the load power exceeds the limit output of the energy storage system, the engine is restarted.

[0094] It should be noted that diesel engines have a low-load efficiency cliff characteristic. That is, when the engine load rate is below 30%, its thermal efficiency will drop sharply from the optimal economic point of 40%-45% to 15%-20%. Under idling conditions, the fuel consumption is as high as 3-5 times that of the optimal economic point. At the same time, a large amount of unburned hydrocarbons and carbon monoxide will be produced.

[0095] Permanent magnet synchronous drive motors maintain a high efficiency of over 85% across the entire load range, and their efficiency does not drop significantly even under extremely low loads. This strategy utilizes this characteristic to completely shut down the engine under zero-load conditions, allowing the energy storage system to drive all auxiliary loads independently, thus strictly limiting the engine's operating time to the high-efficiency range under medium to high loads.

[0096] The system achieves millisecond-level accurate identification of zero-load operating conditions through a multi-sensor fusion algorithm, avoiding power interruptions caused by false triggers. The identification is based on the following core parameters:

[0097] Operating device status parameters:

[0098] Milling wheel torque: continuously below 5% of the rated torque and stable for more than 2 seconds;

[0099] Milling wheel speed: 0 or in idle state, i.e., no cutting load;

[0100] Feed system status: in the upward direction of drill lifting, feed rate is stable and there is no fluctuation in cutting resistance;

[0101] Main hoist operating status: Only performing drill lifting action, no lowering or cutting load;

[0102] Auxiliary system status parameters:

[0103] Mud system: Mud pump current is less than 20% of rated current, and outlet pressure is less than 0.2 MPa;

[0104] Hydraulic system: Main pump pressure is below 3MPa, and no high-flow actuators are activated;

[0105] Walking system: stationary, no walking command given;

[0106] Operator instruction recognition:

[0107] The system receives clear zero-load operation instructions such as drill string lifting completed and waiting to run down drill string;

[0108] The operator has not performed any active cutting, feeding, or other operations for more than 5 seconds;

[0109] When the above parameters are met simultaneously and the duration exceeds the preset threshold, the system determines that it is currently in a zero-load operating condition that can be driven purely by electricity.

[0110] Pure electric drive mode triggering and execution process:

[0111] Prerequisites for triggering:

[0112] 1. The system has been identified as operating under zero load through multi-sensor fusion; 2. The SOC of the energy storage system is greater than or equal to the minimum allowable threshold for pure electric drive; 3. The temperature of the energy storage system is within the normal operating range of 0℃-55℃; 4. There are no fault alarms in the drive motor, controller, and electrical system; 5. The cooling system can be operated independently by an electric drive fan and an electric drive water pump.

[0113] Seamless switching execution steps: 1. Pre-switching preparation phase (0-500ms); 2. The system sends pure electric mode switching commands to each subsystem; 3. The engine's fuel injection system is shut down, and fuel supply is stopped; 4. The engine is kept idling until the remaining fuel is completely burned to avoid unburned fuel residue; 5. Power source switching phase (500-1000ms); 6. The connection between the engine and the power coupling device is disconnected; 7. The drive motor switches from standby state to drive state, smoothly taking over all loads; 8. The engine is completely shut down and enters the shutdown state.

[0114] During pure electric operation: 1. The energy storage system supplies power to all loads, including the drive motor, mud pump, hydraulic pump, and cooling system, through the DC bus; 2. The system monitors the SOC, temperature, and power changes of each load in real time; 3. It continuously monitors changes in operating conditions and is ready to switch back to engine drive mode at any time.

[0115] Further, in step S103, the prediction model is:

[0116] ;

[0117] in, For cutting torque, For engine load rate, This is the current altitude;

[0118] when When the set percentage of the radiator's maximum heat dissipation capacity at the current altitude is exceeded, the fan speed is increased to the maximum value in advance, and the cooling water pump flow rate is increased at the same time; within the range allowed by thermal balance, the fan speed is reduced to reduce parasitic power consumption, and the saved power is used for cutting operations or charging of energy storage systems.

[0119] This model is a predictive model obtained by fitting thermal balance test data of a dual-wheel milling power system. The three input parameters comprehensively characterize the generation and dissipation characteristics of the system's heat load from three dimensions: operating load, power source status, and environmental constraints.

[0120] First, the aforementioned cutting torque As a determining factor of instantaneous thermal load, the cutting torque directly reflects the current cutting load of the twin-wheel milling machine. The greater the load, the higher the power output required by the drive motor and engine. The heat generation power of the power system is approximately proportional to the output power. When cutting hard strata such as hard rock and boulders, the cutting torque will suddenly increase to 120%-150% of the rated value within 100ms, causing the Joule heat of the motor and controller to surge instantaneously, which is the main cause of instantaneous thermal shock in the system. It is used to capture the instantaneous change characteristics of thermal load and provide the most direct early warning signal for the early intervention of the cooling system.

[0121] Secondly, the aforementioned engine load rate As the main source of steady-state heat load, the heat output of the engine combustion exhibits a non-linear relationship with the load rate. When the load rate exceeds 70%, the rate of combustion heat generation increases sharply, and the exhaust temperature rises from 400℃ to over 600℃, transferring a large amount of heat to the system through the exhaust manifold and coolant circuit. Continuous operation at high load rates leads to a continuous accumulation and rise in the temperature of the engine block, engine oil, and hydraulic oil, forming a steady-state heat buildup, which is the main cause of prolonged system overheating. It is used to predict the long-term trend of heat load changes and provide a basis for the steady-state adjustment of the cooling system.

[0122] Finally, the current altitude As a constraint on heat dissipation capacity, the convective heat transfer capacity of a radiator is directly proportional to air density, which decreases exponentially with increasing altitude: at an altitude of 1000 meters, the air density is 89% of that at sea level, at 3000 meters it is 70%, and at 5000 meters it is only 53%. Under the same heat output, the higher the altitude, the less heat the radiator can dissipate, and the more prone the system is to overheating. Traditional cooling systems do not correct for this characteristic, and overheating failures frequently occur during high-altitude construction. By real-time correction of the radiator's limit heat dissipation capacity threshold, it is ensured that the control logic of the cooling system matches the actual heat dissipation capacity at the current altitude.

[0123] This system incorporates a correction curve for the radiator's maximum heat dissipation capacity based on altitude, expressed as follows:

[0124] ;

[0125] in: This represents the actual maximum heat dissipation capacity of the radiator at an altitude of h. 0.12 represents the nominal maximum heat dissipation capacity of the radiator at sea level; 0.12 is the altitude-based heat dissipation attenuation coefficient specified in the engineering, meaning that the heat dissipation capacity decreases by 12% for every 1000 meters increase in altitude.

[0126] Furthermore, a pre-cooling trigger and execution process is set up: Threshold judgment: The system calculates in real time the ratio of the predicted heat load to the current altitude's maximum heat dissipation capacity. The trigger condition is that when R > 80%, it is determined that the system heat load will exceed the current environment's heat dissipation limit within the next 10-30 seconds, posing a risk of overheating of core components.

[0127] Upon intervention, the system immediately performs the following actions:

[0128] Increase the cooling fan speed directly from the current value to the maximum value; increase the cooling water pump flow rate to 120%-150% of the rated flow rate; and simultaneously activate the auxiliary cooling circuits of the hydraulic oil cooler and battery cooler.

[0129] The control effect is to offset the upcoming high heat load impact by establishing sufficient heat dissipation margin in advance, keep the system's maximum temperature below the safe threshold, and avoid temperature spikes and power reduction protection.

[0130] Further, in step S104, the differentiated thermal management strategy includes:

[0131] When the temperature of the energy storage system exceeds the first threshold When the temperature of the energy storage system exceeds the second threshold, the charge / discharge rate is limited to a safe value; when the temperature of the energy storage system exceeds the second threshold... At this time, the maximum power is allowed to drop to the minimum value, while the liquid cooling system is forced to start;

[0132] When the energy storage system temperature is below a set threshold Preheating is performed using a stalled motor heater or a PTC heater before the energy storage system reaches its optimal operating temperature. Previously, the electric auxiliary power was limited to a set percentage of the rated value.

[0133] It should be noted that the electrochemical performance of lithium-ion batteries exhibits a strongly non-linear relationship with temperature. For every 10°C deviation from the optimal operating range, the cycle life will shorten by 20%-30%, and the charge / discharge capacity will decrease by 15%-25%. When the temperature exceeds 45°C, the electrolyte will decompose rapidly, generating a large amount of gas and heat, leading to an increase in internal battery pressure. Simultaneously, the SEI film will rupture, triggering side reactions between the negative electrode active material and the electrolyte, forming a positive feedback loop of thermal runaway, which can lead to fire or explosion in severe cases. When the temperature is below 0°C, the ion mobility of the electrolyte will decrease sharply, the battery internal resistance will increase exponentially, and the charge / discharge capacity will be significantly reduced. During high-current charging, metallic lithium will be deposited on the surface of the negative electrode, resulting in irreversible capacity loss, and may even puncture the separator, causing an internal short circuit. Between 25°C and 40°C, the battery's electrochemical activity is highest, internal resistance is lowest, and charge / discharge efficiency and cycle life are at their optimal levels.

[0134] Based on the above characteristics, this strategy adopts differentiated thermal management measures in different temperature ranges through graded threshold control, so as to maximize the performance of the energy storage system under the premise of safety first.

[0135] This system sets two levels of high temperature warning thresholds and adopts progressive flow limiting and cooling measures according to the degree of temperature exceeding the limit to achieve a dynamic balance between performance and safety.

[0136] The first level is the warning temperature threshold. The control temperature is 45°C, and the trigger condition is that the temperature of any single cell in the energy storage system exceeds [a certain value]. Or the average temperature of the battery pack exceeds -2℃.

[0137] The following actions will be taken: immediately limit the battery charge / discharge rate to 50% of the rated rate; prohibit the battery from discharging at peak power; start the liquid cooling system to 50% of the rated flow rate, and simultaneously open the bypass valve of the battery cooling circuit.

[0138] The heat generated by a battery is proportional to the square of the charge / discharge current. Limiting the charge / discharge rate can directly reduce the rate of Joule heat generation inside the battery, breaking the positive feedback loop of increased temperature, increased internal resistance, increased heat generation, and further temperature increases. At this time, the system prioritizes ensuring basic operating power, temporarily sacrificing some peak power performance to prevent the temperature from continuing to rise into the dangerous range.

[0139] The second level is the dangerous temperature threshold. The temperature is controlled at 55℃ and can be adaptively adjusted according to environmental changes. The temperature of any single battery cell in the energy storage system exceeding this temperature limit is not allowed. Or the average temperature of the battery pack exceeds -2℃, and the duration exceeds 10 seconds.

[0140] The following actions will be taken: reduce the battery's charging and discharging power to the minimum safe value, maintaining power supply only to the system's basic control unit; force the liquid cooling system to start at 100% rated flow, while shutting down all other cooling circuits and concentrating all cooling resources on the battery; disconnect all unnecessary auxiliary loads to further reduce system heat generation; trigger an audible and visual alarm to alert the operator that the battery is currently in a high-temperature dangerous state.

[0141] When the temperature reaches At this point, the battery is nearing thermal runaway, and safety takes precedence above all else. Reducing power to the minimum minimizes internal heat generation, while simultaneously concentrating all cooling resources for forced cooling to quickly bring the battery temperature back to a safe range. If the temperature does not drop to a safe level within 30 seconds... The system will then automatically execute an emergency shutdown procedure to completely cut off the high-voltage power supply.

[0142] The system is equipped with a low-temperature start-up threshold and an optimal operating temperature threshold. It achieves rapid preheating through two complementary heating methods and strictly limits the electric auxiliary power during the preheating process to protect the battery from low-temperature damage.

[0143] At low temperatures, the battery's internal resistance is high, and high-current discharge can cause a sharp drop in terminal voltage, even failing to meet load requirements; high-current charging, on the other hand, can trigger lithium plating on the negative electrode, resulting in irreversible capacity loss. By using graded power limiting, basic operational needs can be guaranteed while preventing irreversible damage to the battery.

[0144] Furthermore, in step S105, the graded storage of feedback energy according to the power characteristics of the energy storage medium includes:

[0145] Transient high-power feedback energy is preferentially stored in power-type energy storage medium supercapacitors, while continuous low-power feedback energy is stored in energy-type energy storage medium power batteries;

[0146] Energy recovery in dual-wheel milling mainly occurs during two conditions: lowering the milling wheel and emergency braking of the vehicle.

[0147] Milling wheel lowering condition: The gravitational potential energy of the milling wheel and drill rod is converted into mechanical energy, which drives the motor to generate electricity. The feedback power can reach 120%-150% of the rated power, and the duration is usually 10-30 seconds.

[0148] Emergency braking condition: The vehicle's kinetic energy is instantly converted into electrical energy, and the feedback power can increase to more than 200% of the rated power within 10ms, but the duration is only a few hundred milliseconds.

[0149] The composite filtering algorithm includes: using a low-pass filter to smooth the feedback power; the filter time constant is dynamically adjusted according to altitude; the higher the altitude, the lower the insulation withstand voltage margin, and the larger the filter time constant, to reduce peaks to a greater extent; even after hierarchical storage, the feedback power will still fluctuate to some extent, causing spikes in the DC bus voltage. In plain environments, the insulation withstand voltage margin of the electrical system is sufficient, and such spikes usually do not cause harm; however, in high-altitude, low-pressure environments:

[0150] 1. The insulation breakdown strength of air decreases linearly with increasing altitude, reaching only 50% of that at sea level at an altitude of 5000 meters.

[0151] 2. The creepage distance and clearance withstand voltage of power devices are significantly reduced.

[0152] 3. When the DC bus voltage spike exceeds the insulation withstand voltage threshold, it will trigger corona discharge. Long-term accumulation will lead to insulation aging, breakdown, and even fire.

[0153] Therefore, filtering algorithms must be used to further smooth the feedback power and suppress voltage spikes.

[0154] The basic working principle of a low-pass filter:

[0155] This scheme uses a first-order low-pass filter to smooth the feedback power, and its transfer function is:

[0156] ;in, is the filter time constant.

[0157] A low-pass filter allows continuous low-frequency power to pass through while suppressing transient high-frequency power spikes. (Time constant) The larger the value, the better the filtering effect and the stronger the peak-shaving ability, but the slower the system response speed; conversely, the smaller the time constant, the faster the response speed, but the weaker the peak-shaving ability.

[0158] Altitude-adaptive time constant adjustment mechanism:

[0159] Traditional filtering algorithms use a fixed time constant, which cannot adapt to changes in insulation performance at high altitudes. This solution dynamically adjusts the filter time constant based on the current altitude.

[0160] ;

[0161] in, Let h be the filter time constant at altitude h; 0.2 is the reference time constant at sea level; 0.2 is the elevation correction factor determined by the engineering calibration.

[0162] The higher the altitude, the lower the air density, and the smaller the electrical insulation withstand voltage margin. A larger time constant is needed to further smooth the feedback power, reduce peaks to a greater extent, reduce DC bus voltage spikes, and ensure electrical safety.

[0163] For example: sea level: =50ms, balancing response speed and filtering effect; Altitude 3000 meters:

[0164] =80ms, enhancing peak reduction capability; Altitude 5000 meters: =100ms, maximizing peak smoothing capability.

[0165] The maximum value of the feedback power is limited to ,in This is the altitude correction factor, which decreases as altitude increases.

[0166] in, This represents the maximum permissible feedback power at an altitude of h. The rated feedback power at sea level; The expression is: .

[0167] For every 1000 meters increase in altitude, the maximum permissible feedback power decreases by 8%. This is because higher altitudes result in lower insulation withstand voltage, lower maximum permissible DC bus voltage, and consequently, lower maximum feedback power. This dual limitation completely eliminates the risk of insulation breakdown due to excessive feedback power in high-altitude environments.

[0168] Furthermore, in step S106, the electrical parameters of the drive system include the drive motor current fluctuation rate. The load parameters of the working device include torque variability. ;pass and The hardness level of the work object is identified by combining the wear status of the work tools, and the hardness of the work object is divided into four levels: soft soil, medium hard rock, hard rock, and boulder. The milling wheel speed and feed rate are adjusted according to the identification results: for each increase in the hardness of the work object, the milling wheel speed and feed rate are reduced by a set percentage, and electric assist torque compensation is added.

[0169] It should be noted that the effective value of the three-phase stator current is collected by the current sensor built into the drive motor controller at a high sampling frequency of 1kHz; the current change rate per unit time is calculated by the sliding window method, with a window size of 10ms and a step size of 1ms. ;in, and These are the maximum and minimum current values ​​within the sliding window, respectively; Given the window time length, the current fluctuation rate directly reflects the instantaneous change rate of the motor's output torque, with an extremely fast response speed, enabling it to capture sudden changes in formation hardness in the first instance.

[0170] Milling wheel torque ripple rate Calculation: Real-time torque values ​​are collected by a torque sensor mounted on the milling wheel spindle at a sampling frequency of 500Hz. The same sliding window method is used to calculate the torque fluctuation rate, which directly reflects the instantaneous change rate of the milling wheel cutting load and is the most direct characterization parameter of the formation hardness, but its response speed is slightly slower than that of the current fluctuation rate.

[0171] The data preprocessing uses a median filtering algorithm to remove sensor noise and interference signals, eliminate obviously abnormal sampling points, and normalize the two volatility parameters to eliminate the influence of dimensions, which facilitates subsequent fusion and identification.

[0172] Tool wear increases cutting resistance and intensifies load fluctuations. Without compensation, the system may misinterpret this as increased formation hardness, leading to unnecessary speed reductions and decreased operational efficiency. This solution utilizes the cumulative cutting energy method to achieve online assessment and compensation for tool wear.

[0173] Tool wear calculation: Where W is the cumulative wear of the tool, and k is the wear coefficient. This represents the real-time cutting power.

[0174] Further, in step S107, the detection conditions for the working device jamming are: the change in the torque of the working device within a set time exceeds a first threshold, and the rotational speed of the working device is lower than a second threshold; the system uses a fixed time window of 500ms to calculate and determine the following two conditions in real time:

[0175] First, the change in the torque of the working device within a 500ms time window exceeds the first threshold. First threshold If the torque is set to 80% of the rated torque and suddenly spikes within a very short time, it indicates that the milling wheel has encountered an obstacle that it cannot cut.

[0176] Secondly, the operating device speed is lower than the second threshold. Second threshold When the speed is set to 5% of the rated speed, the torque spikes while the speed drops to almost zero, indicating that the milling wheel is completely stuck and cannot rotate.

[0177] The system will determine that the working device is stuck and automatically trigger the troubleshooting mode only when both of the above conditions are met at the same time and the duration exceeds 500ms.

[0178] To further reduce the false positive rate, the system also sets the following auxiliary judgment conditions:

[0179] 1. Eliminate interference from operator-initiated stop commands; 2. Eliminate transient torque fluctuations during milling wheel forward / reverse switching; 3. Eliminate abnormal signals caused by sensor malfunctions.

[0180] A stuck fault is only confirmed when the judgment results of three consecutive time windows are all stuck.

[0181] The trouble-solving mode includes: removing the rated power limit of the drive motor, calling the limit discharge power of the energy storage system, and coordinating with the engine to output transient trouble-solving peak torque;

[0182] In distress mode, the engine maintains its maximum output power after environmental correction. It is not allowed to be further overloaded, and the engine output power exceeds Afterwards, it will enter the enriched fuel supply zone, where fuel combustion is incomplete, and fuel consumption and emissions will increase sharply; engine overload will cause the cylinder temperature to rise sharply, and the thermal load will increase significantly, which can easily cause fatal failures such as piston burning and cylinder scoring; the instantaneous response speed of the engine is much slower than that of the electric motor, and it cannot provide the millisecond-level peak torque required to get out of trouble.

[0183] The preset safety constraint strategy includes: the duration of the escape mode does not exceed a set number of seconds, and the normal restrictions are restored immediately after the escape is successful, in order to protect the mechanical and electrical systems.

[0184] The relief mode is an extreme overload operating state. If left unchecked, it will cause irreversible damage to the motor, energy storage system, and transmission system.

[0185] 1. The duration of a single escape mode should not exceed 3-5 seconds. The overload capacity of the drive motor and energy storage system is limited. Prolonged overload will cause the motor winding temperature to rise sharply, generating a large amount of heat inside the battery and triggering the risk of thermal runaway. The 3-5 second time limit is based on the thermal characteristics of the motor and battery, ensuring sufficient escape time while preventing overheating damage to the equipment.

[0186] 2. A maximum of two consecutive energy bursts are allowed in a single escape cycle. Multiple consecutive escapes will lead to heat accumulation in the system, and even if each escape lasts no more than 5 seconds, it may cause the equipment to overheat. Limiting the number of consecutive escapes can effectively control the rate of heat accumulation.

[0187] 3. The interval between two energy bursts should be no less than 30 seconds. This 30-second interval allows the motor and battery sufficient time to dissipate heat, bringing the temperature down to a safe range and preparing for the next extrication attempt. Simultaneously, the interval also allows the operator to observe the jamming situation and determine whether the milling wheel position needs adjustment before attempting to extricate the vehicle.

[0188] 4. When the milling wheel torque drops to below 120% of the rated torque and the speed recovers to above 10% of the rated speed, the system is deemed to have successfully overcome the obstacle. After the obstacle is overcome, the system immediately releases the overload limit of the motor and energy storage system, restores the normal power constraint, and switches the engine operating point back to the green economic operating zone, returning to the conventional energy management mode.

[0189] 5. If two consecutive attempts to resolve the obstacle fail, the system will automatically exit the obstacle-resolving mode, trigger an audible and visual alarm, and prompt the operator to intervene manually.

[0190] At the same time, the system will automatically record data such as jam position, torque, and speed, providing a basis for subsequent fault analysis.

[0191] Further, in step S108, the electrical safety parameters include the DC bus-to-ground insulation resistance, and the environmental condition parameters include ambient air pressure; when the insulation resistance is lower than the altitude-corrected safety threshold... Or when the ambient air pressure is lower than the set threshold, the upper limit of the DC bus voltage will be reduced from... Reduce to ,in This is the altitude voltage derating factor, which decreases with increasing altitude; simultaneously, reducing the switching frequency of power devices reduces... It suppresses discharge phenomena caused by electromagnetic interference and high-frequency harmonics.

[0192] It should be noted that the power system of the twin-wheel milling machine adopts a high-voltage DC bus architecture, which provides sufficient air insulation performance in plain environments, ensuring safe and stable operation of the electrical system. However, in high-altitude, low-pressure environments: for every 1000 meters increase in altitude, atmospheric pressure decreases by approximately 10 kPa, and air density decreases by approximately 10%; the insulation breakdown strength of air decreases linearly with decreasing air pressure, reaching only 50% of that at sea level at an altitude of 5000 meters; the high-frequency harmonics and high voltage change rate generated by the switching of power devices exacerbate local electric field concentration, easily triggering corona discharge; long-term accumulation of corona discharge leads to aging and carbonization of the insulation layer, ultimately causing insulation breakdown, short circuits, or even fires.

[0193] Traditional electrical protection schemes have the following drawbacks: fixed threshold protection, lack of altitude adaptability; single protection measures with limited effectiveness; passive response with severe lag.

[0194] This implementation scheme is based on Paschen's law and the corona discharge mechanism, and uses a combination of insulation resistance and ambient air pressure to determine and trigger protection. Simultaneously, it adaptively lowers the upper limit of the DC bus voltage according to altitude, thereby reducing the electric field strength at its source; and it reduces the switching frequency of power devices to decrease... This suppresses partial discharge caused by high-frequency harmonics. The combined effect of these three measures significantly reduces the electrical failure rate in high-altitude environments while ensuring the system's basic operational performance.

[0195] Specifically, Paschen's law reveals the relationship between gas breakdown voltage and gas pressure and electrode gap, and its simplified expression is: ;in, ρ is the gas breakdown voltage; p is the gas pressure; d is the electrode gap; A and B are gas constants; This represents the secondary electron emission coefficient.

[0196] With a fixed electrode gap, the breakdown voltage of air is approximately proportional to the air pressure. The higher the altitude, the lower the air pressure, the lower the breakdown voltage, and the more prone the electrical system is to insulation breakdown.

[0197] Secondly The relationship with corona discharge is that corona discharge refers to the phenomenon of localized ionization of air in areas with high electric field strength, such as the tips of wires or the pins of power devices, within a non-uniform electric field. Power devices generate extremely high voltage change rates during switching, typically reaching 5-10 kV / μs.

[0198] high This can lead to the generation of numerous high-frequency harmonics, exacerbating local electric field concentration; it can also create displacement currents on the surface of the insulation layer, causing it to heat up and age; it can lower the air breakdown threshold, making corona discharge more likely to occur; and it can effectively reduce the switching frequency of power devices. This suppresses the generation of high-frequency harmonics, thereby significantly reducing the risk of corona discharge.

[0199] It should be noted that reducing the DC bus voltage is the most direct and effective measure to suppress corona discharge and insulation breakdown, because the electric field strength is proportional to the voltage; when the voltage is reduced, the electric field strength will also be reduced accordingly.

[0200] The system adaptively reduces the upper limit of the DC bus voltage based on the current altitude. ; This represents the upper limit of the DC bus voltage at altitude h. This refers to the rated bus voltage at sea level. The voltage derating factor is the altitude-based factor, which decreases linearly with increasing altitude. Its expression is: .

[0201] To avoid system shocks and power interruptions caused by sudden voltage changes, a ramp function is used for smooth transition of the voltage derating, with a transition time of 5-10 seconds. Simultaneously, the system automatically adjusts the motor control parameters based on the reduced bus voltage to compensate for the power loss caused by the voltage drop to the greatest extent possible, ensuring that basic operational performance is not affected.

[0202] Reducing the switching frequency of power devices can effectively reduce... This suppresses the generation of high-frequency harmonics, thereby significantly reducing the risk of corona discharge.

[0203] 1. Switching frequency derating ratio and control logic: When the protection condition is triggered, the system will reduce the switching frequency of the power devices by 20%-30% from the rated value.

[0204] For example: the rated switching frequency is 10kHz, and after derating it is 7-8kHz; after the switching frequency is reduced, the number of switching operations of the power device decreases, and the voltage change rate per switching operation increases. This will also decrease accordingly. Experimental data shows that a 30% reduction in switching frequency... It can reduce the frequency of high-frequency harmonics by about 40%, reduce the frequency of high-frequency harmonics by about 50%, and reduce the probability of corona discharge by about 70%.

[0205] 2. Optimization of the reduction ratio:

[0206] The switching frequency cannot be reduced indefinitely, because an excessively low switching frequency will increase the motor torque ripple, resulting in significant vibration and noise; an excessively low switching frequency will increase the conduction loss of power devices, leading to increased device temperature; a derating ratio of 20%-30% is the optimal value verified by a large number of experiments, which can effectively suppress corona discharge and keep the impact on system performance and device temperature within an acceptable range.

[0207] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An energy management strategy for a dual-wheel milling green power system, characterized in that, Includes the following steps: S101: Based on the data collected in real time by the environmental parameter sensing device, the output characteristics of the engine under the current environmental conditions are dynamically corrected, and the engine operating point is limited to the green economic operating zone defined by the excess air coefficient and fuel economy index through the optimization algorithm. S102: Real-time monitoring of the state of charge of the energy storage system; under steady-state conditions, controlling the engine to operate at the optimal economic operating point and recovering excess power; under conditions of instantaneous high torque, controlling the drive motor to intervene instantaneously to provide peak torque assistance. S103: Based on real-time operating parameters and environmental conditions, a predictive model is used to predict the trend of system heat load changes, adjust the operating parameters of the cooling system in advance, and incorporate the parasitic power consumption of the heat dissipation system into the global energy optimization target; S104: Implement differentiated thermal management strategies based on the temperature of the energy storage system. At high temperatures, limit the charge / discharge rate and enhance cooling; at low temperatures, preheat and limit electric auxiliary power. S105: Under energy recovery conditions, the drive motor is switched to power generation mode, the feedback energy is stored in stages according to the power characteristics of the energy storage medium, and a composite filtering algorithm is used to smooth the transient feedback power. S106: By analyzing the fluctuation characteristics of the electrical parameters of the drive system and the load parameters of the working device, combined with the wear status of the working tools, the hardness level of the working object can be identified in real time, and the operating parameters of the working device can be dynamically adjusted. S107: When the working device is stuck, it enters the trouble-relief mode, which allows the drive motor to be overloaded for a short time and calls the limit discharge power of the energy storage system. The trouble-relief process is controlled by a preset safety constraint strategy. S108: When electrical safety parameters or environmental condition parameters are lower than their respective preset thresholds, actively reduce the upper limit of DC bus voltage and the switching frequency of power devices to suppress discharge phenomena.

2. The energy management strategy for the dual-wheel milling green power system according to claim 1, characterized in that, In step S101, the environmental parameter sensing device includes an atmospheric pressure sensor and an oxygen sensor. The dynamically corrected engine output characteristics include: The extreme output external characteristic curve of the engine is reconstructed in real time using an altitude-oxygen content correction model. The correction formula for the extreme output external characteristic curve is as follows: ； in, This represents the actual allowable output power limit at an altitude of h. The nominal power is at the reference altitude; k is the altitude derating factor; h is the actual installation altitude. Used as a reference elevation; The boundary of the green economic operating zone is jointly defined by the excess air coefficient λ and the brake ratio fuel consumption rate BSFC. When the oxygen sensor detects that the oxygen concentration is lower than the set threshold, the range of the green economic operating zone is narrowed, and the engine is forced to reduce its output power.

3. The energy management strategy for the dual-wheel milling green power system according to claim 1, characterized in that, In step S102, the control strategy under steady-state conditions includes peak shaving and valley filling logic: When the actual load power Power output below the engine's optimal economic operating point At that time, the engine is still operating at its optimal economic operating point, with excess power... - The energy storage system is charged by a generator; The control strategy under instantaneous high torque conditions includes electric power assist logic: When the actual load power Exceeding the engine's environmentally modified power limit At that time, the drive motor momentarily intervenes to provide peak torque assistance, and the power provided by the drive motor is Meanwhile, the engine maintains its position. The purpose is to avoid entering the enrichment supply area.

4. The energy management strategy for the dual-wheel milling green power system according to claim 1, characterized in that, It also includes steps for extending intelligent start-stop and pure electric drive strategies: When the dual-wheel milling machine is in a zero-load condition such as drilling or low-load operation of the mud system, the system is switched to pure electric drive mode, the engine is turned off, and the energy storage system supplies power alone. When the state of charge (SOC) of the energy storage system is lower than the set threshold or the load power exceeds the limit output of the energy storage system, the engine will be restarted.

5. The energy management strategy for the dual-wheel milling green power system according to claim 1, characterized in that, In step S103, the prediction model is: ； in, For cutting torque, For engine load rate, This is the current altitude; when When the set percentage of the radiator's maximum heat dissipation capacity at the current altitude is exceeded, the fan speed is increased to the maximum value in advance, and the cooling water pump flow rate is increased at the same time; within the range allowed by thermal balance, the fan speed is reduced to reduce parasitic power consumption, and the saved power is used for cutting operations or charging of energy storage systems.

6. The energy management strategy for the dual-wheel milling green power system according to claim 1, characterized in that, In step S104, the differentiated thermal management strategy includes: When the temperature of the energy storage system exceeds the first threshold When the temperature of the energy storage system exceeds the second threshold, the charge / discharge rate is limited to a safe value; when the temperature of the energy storage system exceeds the second threshold... At this time, the maximum power is allowed to drop to the minimum value, while the liquid cooling system is forced to start; When the energy storage system temperature is below a set threshold At this time, preheating is performed using a stalled motor heater or a PTC heater before the energy storage system reaches its optimal operating temperature. Previously, the electric auxiliary power was limited to a set percentage of the rated value.

7. The energy management strategy for the dual-wheel milling green power system according to claim 1, characterized in that, In step S105, the graded storage of feedback energy according to the power characteristics of the energy storage medium includes: Transient high-power feedback energy is preferentially stored in power-type energy storage medium supercapacitors, while continuous low-power feedback energy is stored in energy-type energy storage medium power batteries; The composite filtering algorithm includes: using a low-pass filter to smooth the feedback power; the filter time constant is dynamically adjusted according to the altitude. The higher the altitude, the lower the insulation withstand voltage margin, and the larger the filter time constant, so as to reduce peaks to a greater extent. The maximum value of the feedback power is limited to ,in This is the altitude correction factor, which decreases as altitude increases.

8. The energy management strategy for the dual-wheel milling green power system according to claim 1, characterized in that, In step S106, the electrical parameters of the drive system include the drive motor current fluctuation rate. The load parameters of the working device include torque variability. ;pass and The hardness level of the work object is identified by combining the wear status of the work tools, and the hardness of the work object is divided into four levels: soft soil, medium hard rock, hard rock, and boulder. The milling wheel speed and feed rate are adjusted according to the identification results: for each increase in the hardness of the work object, the milling wheel speed and feed rate are reduced by a set percentage, and electric assist torque compensation is added.

9. The energy management strategy for the dual-wheel milling green power system according to claim 1, characterized in that, In step S107, the detection condition for the work device jamming is: the change in the torque of the work device within a set time exceeds a first threshold, and the rotational speed of the work device is lower than a second threshold. The trouble-solving mode includes: removing the rated power limit of the drive motor, calling the limit discharge power of the energy storage system, and coordinating with the engine to output the transient trouble-solving peak torque; The preset safety constraint strategy includes: the duration of the escape mode does not exceed a set number of seconds, and the normal restrictions are restored immediately after the escape is successful, in order to protect the mechanical and electrical systems.

10. The energy management strategy for the dual-wheel milling green power system according to claim 1, characterized in that, In step S108, the electrical safety parameters include the DC bus insulation resistance to ground, and the environmental condition parameters include the ambient air pressure. When the insulation resistance is below the altitude-corrected safety threshold Or when the ambient air pressure is lower than the set threshold, the upper limit of the DC bus voltage will be reduced from... Reduce to ,in This is the voltage derating factor based on altitude, which decreases as altitude increases. At the same time, reduce the switching frequency of power devices and decrease It suppresses discharge phenomena caused by electromagnetic interference and high-frequency harmonics.

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