Train inertia energy recovery and energy storage system and method

Abstract

The application discloses a train inertial energy recovery and energy storage system and method, and relates to the technical field of inertial energy recovery and energy storage, which comprises an inertial kinetic energy capturing mechanism, a rotating speed matching unit, a power generation unit, a power conversion control system, a super capacitor energy storage cabinet and a whole vehicle controller. In the train high-speed sliding stage, the inertial mechanical energy of the wheel is extracted by the mechanical capturing mechanism and is converted into electric energy and stored in the super capacitor. The electric energy is released in the train starting stage. The mechanical device is out of work in the emergency braking. The application breaks through the limitation of traditional electric energy storage only for braking recovery, expands the energy recovery to the whole process of train high-speed sliding, improves the energy recovery efficiency compared with the existing equipment, improves the comprehensive power saving rate of the train, reduces the brake pad wear and reduces the peak load of the power grid. The train body has small modification, is suitable for high-speed trains, city area trains and subway trains and has engineering application value.

Description

Technical Field

[0001] This invention relates to the field of inertial energy recovery and storage technology, and more specifically to a train inertial energy recovery and storage system and method. Background Technology

[0002] With the rapid development of rail transit, trains start and stop frequently, and the braking phase contains a huge amount of inertial kinetic energy. At present, the mainstream regenerative braking energy recovery method in the industry is the pure electric supercapacitor energy storage mode, which only activates energy recovery for a short period of ten seconds when the brake pads perform the braking action. A large amount of inertial kinetic energy generated during the long-distance high-speed coasting phase of the train cannot be utilized and is ultimately converted into heat energy by the friction of the brake pads and dissipated into the air, resulting in a very prominent energy waste problem.

[0003] The existing technology has the following obvious drawbacks: First, the energy recovery window is very short, limited to the emergency braking phase. During the high-speed gliding process of the train, the huge inertial kinetic energy is wasted. Conventional supercapacitor energy storage equipment can only achieve an overall power saving rate of 13%-17%. Secondly, in order to recover as much electrical energy as possible, the braking system needs to increase the braking force of the brake pads, which aggravates the wear of the brake pads and brake discs, resulting in a short replacement cycle for parts and high maintenance costs in the later stage. Third, supercapacitors are frequently charged and discharged at high rates, which causes them to age quickly and result in high replacement costs. Fourth, the train relies entirely on the overhead contact line for power during startup and acceleration, resulting in high instantaneous peak power. This forces rail transit operators in various regions to expand traction substations, leading to high infrastructure investment costs. Fifth, retrofitting existing energy storage equipment often requires large-scale modifications to the vehicle body structure, making it difficult to install on existing trains.

[0004] Therefore, how to propose a train inertial energy recovery and storage system and method to recover inertial kinetic energy during the train's coasting phase, improve driving safety, reduce the amount of vehicle body modification, and overcome the shortcomings of existing technologies is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a train inertial energy recovery and storage system and method, which extends the energy recovery range from the traditional braking stage to the entire high-speed coasting process of the train. Simultaneously, it sets up strict safety control logic to prioritize the safety of the original vehicle braking, effectively improving the utilization rate of inertial kinetic energy and reducing the train's electricity costs and subsequent maintenance expenses. To achieve the above objectives, the present invention adopts the following technical solution: A train inertial energy recovery and storage system includes: Inertial kinetic energy harvesting mechanism, speed matching unit, power generation unit, power conversion control system, supercapacitor energy storage cabinet and vehicle controller; The inertial kinetic energy harvesting mechanism is connected to the train wheel axle drive, and the vehicle controller is connected to the inertial kinetic energy harvesting mechanism, the speed matching unit, the power generation unit, the power conversion control system, and the supercapacitor energy storage cabinet respectively. The vehicle controller is connected to the train vehicle control system and distinguishes between high-speed coasting, emergency braking, and acceleration phases based on the train's operating speed signal. When the train is in a high-speed coasting condition, the vehicle controller activates the inertial kinetic energy capture mechanism. The mechanical energy output by the rotation of the wheels is transmitted to the power generation unit after being adjusted by the speed matching unit. The electrical energy output by the power generation unit is stored in the supercapacitor energy storage cabinet after being stabilized and filtered by the power conversion control system. When the train is in an emergency braking situation, the vehicle controller quickly cuts off the inertial energy capture mechanism and the power generation unit, and the train relies on the brake pads for braking. When the train is in the acceleration phase, the vehicle controller controls the supercapacitor energy storage cabinet to release electrical energy, which, in conjunction with the traction motor, drives the train forward.

[0006] Optionally, the speed matching unit is provided with multiple speed gears, each gear corresponding to a fixed transmission ratio; The vehicle controller collects the real-time running speed of the train and, based on the efficiency calculation model of multi-stage transmission series, solves the total energy recovery efficiency and the operating speed of the power generation unit under different gears. The speed ratio is dynamically adjusted with the rated high-efficiency speed range of the power generation unit as a constraint. The higher the train's operating speed, the smaller the corresponding total transmission ratio of the system, ensuring that the input speed of the power generation unit is kept within the high-efficiency power generation range, thus maximizing the energy recovery efficiency during the full high-speed coasting phase.

[0007] Optionally, the speed matching unit is equipped with multiple sets of speed and torque detection modules, which are respectively arranged at the wheel axle input end, the planetary gear transmission mechanism output end, the speed matching unit output end and the power generation unit input end; The vehicle controller has a built-in transmission efficiency calculation module that uses a data-driven efficiency prediction method to quantitatively evaluate the energy recovery link and combines real-time vehicle speed and detection signals to achieve optimal matching of gears.

[0008] Optionally, the power conversion control system has a built-in overvoltage protection module, overload protection module, and short-circuit protection module; When the supercapacitor voltage reaches the set upper limit, the vehicle controller disconnects the power generation unit and stops energy storage; When voltage fluctuations occur in the train's power grid, the output power is adjusted to avoid impacting the train's vehicle control system.

[0009] Optionally, the power conversion control system further includes a built-in adaptive grid fluctuation smoothing module; The adaptive power grid fluctuation mitigation module collects multi-source operating features in real time, including contact network voltage, train traction power, supercapacitor state of charge, train speed and braking status. It uses the MIC maximum information coefficient to quantify the nonlinear correlation between each feature and power grid voltage fluctuation, and combines the XGBoost algorithm to output the importance value of each feature to voltage fluctuation. Core features are then selected to form the power grid fluctuation prediction input feature set. A voltage fluctuation probability prediction model is constructed based on the input feature set. The probability distribution and confidence interval of the future short-term grid voltage are obtained through kernel density estimation. The charging and discharging power commands of the power conversion system are dynamically adjusted according to the upper and lower limits of the confidence interval to smooth out the contact network voltage fluctuations and avoid overvoltage and undervoltage impacts on the train vehicle control system.

[0010] Optionally, the power conversion control system further includes a built-in charge-discharge optimization control module; The charge-discharge optimization control module constructs an improved loss function as the optimization target of power control. The original loss term is the mean square error of the supercapacitor terminal voltage deviation and the charge-discharge power command deviation, and the auxiliary loss term is the penalty term for the high-frequency fluctuation component of the charge-discharge power. The total loss function is formed by combining the weighted coefficients. Throughout the entire energy recovery and release process, the optimal charging and discharging power command is solved in real time with the goal of minimizing the total loss function. This suppresses high-frequency power fluctuations, reduces the sudden change in the charging and discharging rate of the supercapacitor while ensuring energy conversion efficiency, delays capacitor aging, and extends the service life of the energy storage system.

[0011] Optionally, the inertial kinetic energy harvesting mechanism includes: a clutch assembly and a planetary gear transmission mechanism; The clutch assembly is controlled by the vehicle controller; During the train startup phase, the clutch disengages, and the inertial kinetic energy capture mechanism idles. During coasting, the clutch engages, and the wheel axle drives the planetary gear mechanism to rotate. During emergency braking, the clutch disengages immediately without interfering with the original vehicle braking system.

[0012] Optionally, the vehicle controller divides the speed threshold: when the train's running speed is greater than 5 km / h, it enters the recyclable zone; during the 0-5 km / h start-up phase, the clutch remains disengaged to avoid the additional resistance of wheel-rail static friction at 0-5 km / h and reduce start-up energy consumption.

[0013] Optionally, the vehicle controller is configured with a priority logic hierarchy: emergency braking > train start-up energy storage and charging > energy recovery during coasting.

[0014] Optionally, the entire energy storage assembly can be arranged in the empty space at the bottom of the carriage without cutting or modifying the main structure of the car body; it can be connected to the wheel axle only through the flange structure, and can be used for later installation on existing trains or as a factory-fitted component for new cars.

[0015] Optionally, a method for recovering and storing train inertial energy includes: Step 1, Train acceleration phase: The vehicle controller disengages the clutch, the inertial energy capture mechanism stops working, and the train runs entirely on the power of the overhead contact line. Step 2, High-speed coasting stage: When the vehicle speed is >5km / h, the clutch engages, the wheel axle drives the planetary gear mechanism to rotate, and mechanical energy is converted into electrical energy and stored in the supercapacitor energy storage cabinet. Step 3, Train restarts: The supercapacitor energy storage cabinet prioritizes releasing electrical energy to assist the traction motor in doing work, reducing the instantaneous load on the power grid; Step 4, Emergency Braking: The vehicle controller receives the braking signal, the clutch quickly disengages, the supercapacitor energy storage cabinet stops working, and the original vehicle braking system independently completes the braking. Step 5, Low speed range of 0-5km / h: The energy storage system remains dormant throughout the entire process, overcoming the static and dynamic friction resistance during startup, allowing the train to start smoothly.

[0016] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a train inertial energy recovery and storage system and method, which has the following beneficial effects: 1. This invention extends the energy recovery time from the traditional emergency braking time of a dozen seconds to the entire process of long-distance high-speed gliding of the train. The energy recovery efficiency is improved by more than 30% compared with traditional supercapacitor equipment, and the overall power saving rate of the train reaches 22-28%, which greatly saves traction power. 2. During the coasting phase, some inertial kinetic energy is consumed in advance, reducing the workload of the brake pads, extending the service life of the brake disc and brake pads, and significantly reducing the later maintenance costs; 3. During the train's start-up phase, the supercapacitor releases electrical energy, reducing the peak load on the power grid and decreasing the investment in expanding the traction substation. 4. The mechanical structure undertakes most of the energy conversion task, which reduces the charging and discharging frequency of the supercapacitor, delays the aging of the supercapacitor, and extends the service life of the energy storage element. 5. The equipment is installed at the bottom of the carriage and relies on the flange to connect the wheel axle. The amount of modification to the car body is very small. It can be adapted to 525-ton high-speed train sets, urban trains and subway trains. It can be implemented for new trains and for the modification of existing trains. 6. Strict safety control logic is set up, with the original vehicle's emergency braking command having the highest priority. The mechanical energy storage system can be disconnected at any time without changing the original vehicle's braking control program, thus ensuring full driving safety. At the same time, it avoids the 0-5km / h static friction range, so as not to increase the train's starting resistance. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a train inertial energy recovery and storage method provided by the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention discloses a train inertial energy recovery and storage system, comprising: Inertial kinetic energy harvesting mechanism, speed matching unit, power generation unit, power conversion control system, supercapacitor energy storage cabinet and vehicle controller; The inertial kinetic energy harvesting mechanism is connected to the train wheel axle drive, and the vehicle controller is connected to the inertial kinetic energy harvesting mechanism, the speed matching unit, the power generation unit, the power conversion control system, and the supercapacitor energy storage cabinet respectively. The vehicle controller is connected to the train vehicle control system and distinguishes between high-speed coasting, emergency braking, and acceleration phases based on the train's operating speed signal. When the train is in a high-speed coasting condition, the vehicle controller activates the inertial kinetic energy capture mechanism. The mechanical energy output by the rotation of the wheels is transmitted to the power generation unit after being adjusted by the speed matching unit. The electrical energy output by the power generation unit is stored in the supercapacitor energy storage cabinet after being stabilized and filtered by the power conversion control system. When the train is in an emergency braking situation, the vehicle controller quickly cuts off the inertial energy capture mechanism and the power generation unit, and the train relies on the brake pads for braking. When the train is in the acceleration phase, the vehicle controller controls the supercapacitor energy storage cabinet to release electrical energy, which, in conjunction with the traction motor, drives the train forward.

[0021] Furthermore, the speed matching unit is equipped with multiple speed gears, each gear corresponding to a fixed transmission ratio; The vehicle controller collects the real-time running speed of the train and, based on the efficiency calculation model of multi-stage transmission series, solves the total energy recovery efficiency and the operating speed of the power generation unit under different gears. The speed ratio is dynamically adjusted with the rated high-efficiency speed range of the power generation unit as a constraint. The higher the train's operating speed, the smaller the corresponding total transmission ratio of the system, ensuring that the input speed of the power generation unit is kept within the high-efficiency power generation range, thus maximizing the energy recovery efficiency during the full high-speed coasting phase.

[0022] Furthermore, the speed matching unit is equipped with multiple sets of speed and torque detection modules, which are respectively arranged at the wheel axle input end, the planetary gear transmission mechanism output end, the speed matching unit output end and the power generation unit input end; The vehicle controller has a built-in transmission efficiency calculation module that uses a data-driven efficiency prediction method to quantitatively evaluate the energy recovery link and combines real-time vehicle speed and detection signals to achieve optimal matching of gears.

[0023] In a specific implementation, the vehicle controller incorporates a transmission efficiency calculation module. It employs a data-driven efficiency prediction method to quantitatively evaluate the energy recovery link, and combines real-time vehicle speed with detection signals to achieve optimal gear matching. The specific calculation rules and parameter definitions are as follows: (1) Overall efficiency model of energy recovery transmission chain The complete energy conversion chain from mechanical energy input to electrical energy output from the axle is composed of four stages of components connected in series: clutch assembly, planetary gear transmission mechanism, speed matching unit, and power generation unit. The overall efficiency is the product of the efficiencies of each stage of the component chain, and the calculation formula is as follows: ; in, : Overall efficiency of the energy recovery transmission chain, characterizing the overall conversion efficiency of wheel and axle inertial kinetic energy into electrical energy; The mechanical transmission efficiency of the clutch assembly is determined by the clutch friction characteristics; The mechanical transmission efficiency of a planetary gear transmission mechanism is determined by the gear meshing characteristics and lubrication conditions. The speed matching unit determines the transmission efficiency of the current gear, which varies with the gear ratio. The electromechanical conversion efficiency of the power generation unit at the current operating speed reaches its peak within the rated speed range.

[0024] (2) Efficiency calculation formula for single-stage transmission components

[0025] The efficiency of each level of mechanical transmission component is calculated using the ratio of output power to input power, expressed as: ; in, The transmission efficiency of the x-th stage transmission component; , : These represent the input speed (r / min) and input torque (N) of the x-th stage transmission component, respectively. m); , : These represent the output speed (r / min) and output torque (N) of the x-th stage transmission component, respectively. m).

[0026] The speed and torque detection module collects speed and torque data from each node in real time, substitutes them into the above formula to calculate the actual transmission efficiency, and dynamically calibrates the theoretical efficiency model to improve gear matching accuracy.

[0027] (3) Mapping relationship between wheel and axle speed and train speed

[0028] The real-time operating speed of the train and the wheel and axle speed satisfy a kinematic correspondence, and the calculation formula is as follows: ; in, Real-time train speed, unit: km / h; : Rolling radius of train wheels, unit: m; : Rotational speed of train wheel axles, unit: r / min.

[0029] (4) Optimal matching logic for gear shifting

[0030] Suppose the speed matching unit has N gear levels, and the transmission ratio corresponding to the k-th gear is... (k=1, 2, ..., N); combined with the fixed transmission ratio of the planetary gear transmission mechanism Therefore, the total transmission ratio of the system corresponding to the kth gear is: ; The corresponding input speed of the generator unit is: ; The vehicle controller performs optimization calculations across all gears: first, it filters out gears that meet the high-efficiency speed constraints of the generator unit. The candidate gear set; then select the overall efficiency from the candidate set. The highest gear is used as the current gear, and the shift actuator of the speed matching unit is controlled to complete the gear switching; if there is no candidate gear that meets the speed constraint, the current gear is maintained and the vehicle speed change is continuously monitored.

[0031] Furthermore, the power conversion control system has a built-in overvoltage protection module, overload protection module, and short-circuit protection module; When the supercapacitor voltage reaches the set upper limit, the vehicle controller disconnects the power generation unit and stops energy storage; When voltage fluctuations occur in the train's power grid, the output power is adjusted to avoid impacting the train's vehicle control system.

[0032] Furthermore, the power conversion control system also includes a built-in adaptive grid fluctuation smoothing module; The adaptive power grid fluctuation mitigation module collects multi-source operating features in real time, including contact network voltage, train traction power, supercapacitor state of charge, train speed and braking status. It uses the MIC maximum information coefficient to quantify the nonlinear correlation between each feature and power grid voltage fluctuation, and combines the XGBoost algorithm to output the importance value of each feature to voltage fluctuation. Core features are then selected to form the power grid fluctuation prediction input feature set. A voltage fluctuation probability prediction model is constructed based on the input feature set. The probability distribution and confidence interval of the future short-term grid voltage are obtained through kernel density estimation. The charging and discharging power commands of the power conversion system are dynamically adjusted according to the upper and lower limits of the confidence interval to smooth out the contact network voltage fluctuations and avoid overvoltage and undervoltage impacts on the train vehicle control system.

[0033] Furthermore, the power conversion control system also includes a built-in charge and discharge optimization control module; The charge-discharge optimization control module constructs an improved loss function as the optimization target of power control. The original loss term is the mean square error of the supercapacitor terminal voltage deviation and the charge-discharge power command deviation, and the auxiliary loss term is the penalty term for the high-frequency fluctuation component of the charge-discharge power. The total loss function is formed by combining the weighted coefficients. Throughout the entire energy recovery and release process, the optimal charging and discharging power command is solved in real time with the goal of minimizing the total loss function. This suppresses high-frequency power fluctuations, reduces the sudden change in the charging and discharging rate of the supercapacitor while ensuring energy conversion efficiency, delays capacitor aging, and extends the service life of the energy storage system.

[0034] In a specific implementation, the power conversion control system, serving as the energy conversion hub between the power generation unit, the supercapacitor energy storage cabinet, and the train traction power grid, incorporates a triple basic protection module for overvoltage, overload, and short circuit. Overvoltage protection: Real-time acquisition of supercapacitor terminal voltage. When the voltage reaches the set upper limit threshold, the vehicle controller simultaneously sends a shutdown command to the power generation unit and the power conversion system to cut off energy input and prevent damage from overcharging of the supercapacitor. Overload protection: Monitor the output circuit current. When it continuously exceeds 1.2 times the rated current, gradually reduce the transmission power. When it exceeds 1.5 times the rated current, directly disconnect the main circuit. Short circuit protection: A hardware-level short circuit detection circuit is used to cut off the power circuit within 5ms when an output short circuit is detected, thus isolating the fault point.

[0035] When voltage fluctuations occur in the train's overhead contact line, the power conversion system dynamically adjusts the charging and discharging power by regulating the duty cycle of the bidirectional DC-DC converter, thereby reducing the amplitude of the fluctuations transmitted to the train's vehicle control system.

[0036] 1. Adaptive Power Grid Fluctuation Smoothing Module

[0037] The adaptive voltage fluctuation suppression module addresses the characteristics of large load fluctuations and strong start-stop impacts in the power grid traction system. It achieves active voltage suppression through a three-level logic process: feature selection, probability prediction, and dynamic adjustment. The specific implementation is as follows: (1) Core feature screening The module collects five types of initial operating characteristics in real time: real-time voltage of the overhead contact line. Train traction power Supercapacitor State of Charge (SOC), Train Speed ​​(v), Braking Command Signal The core features are selected by jointly using the MIC (Maximum Information Coefficient) and XGBoost algorithms. ① Calculation of Maximum Information Coefficient (MIC): The maximum information coefficient is used to quantify the strength of linear and nonlinear associations between two variables. The calculation formula is as follows: ; Wherein, X and Y are two feature variables whose correlation degree is to be calculated; : Divide the feature space into Mutual information between two variables in a grid; : The upper limit of grid division, taken as the sample size n raised to the power of 0.6; MIC: The value range is [0, 1], the larger the value, the stronger the correlation between variables. Calculate the MIC values ​​of each operating feature and the catenary voltage fluctuation, remove weakly correlated features with MIC values ​​below 0.2, and retain the strongly correlated features as the candidate set.

[0038] ② XGBoost feature importance ranking is based on training the XGBoost voltage fluctuation regression model with candidate features, outputting the gain importance value of each feature, sorting them from high to low importance, and selecting features with a cumulative importance ratio of more than 90% to form the final input feature set.

[0039] (2) Voltage fluctuation probability prediction and confidence interval calculation

[0040] Based on the selected input feature set, a short-term voltage fluctuation probability prediction model is constructed. Kernel density estimation is used to obtain the probability distribution of the contact network voltage within the next 1 second, and then the confidence interval is calculated. The kernel density estimation formula is as follows: ; in, : Probability density function of overhead contact line voltage; n: Number of historical voltage samples; h: Kernel density estimation bandwidth coefficient, determined using the Silverman criterion; : The i-th historical voltage sample value; Gaussian kernel function, expression is .

[0041] Integrating the probability density function yields the cumulative distribution function. Solve for the nominal confidence level The following is the confidence interval for voltage fluctuation: ; in, Nominal quantile level The corresponding voltage quantile value; : Upper boundary of the confidence interval; : Lower boundary of the confidence interval.

[0042] (3) Adaptive power regulation strategy

[0043] The vehicle controller performs power adjustment based on the voltage confidence interval boundaries: Predicted upper voltage boundary Exceeding the grid's allowable limit When this happens, the supercapacitor charging power is reduced proportionally until the predicted voltage returns to the allowable range; Predicted lower voltage boundary Below the lower limit of the power grid At the same time, the supercapacitor is controlled to release supplementary power to raise the contact network voltage to the normal range; The predicted voltage range is completely within Within the specified range, maintain the current charging and discharging power to ensure optimal energy recovery efficiency.

[0044] 2. Charge / Discharge Optimization Control Module

[0045] To address the issues of frequent charging and discharging leading to aging and sudden power fluctuations exacerbating losses in supercapacitors, the charge / discharge optimization control module employs an improved loss function to optimize power commands, balancing efficiency and lifespan. The specific implementation is as follows: (1) Construction of improved loss function The total loss function is a weighted combination of the original control loss term and the high-frequency fluctuation penalty term, and the calculation formula is as follows: ; in, Total loss function, with the control objective being to minimize the total loss; The original control loss term characterizes the control deviation between voltage and power. High-frequency fluctuation penalty term, used to suppress high-frequency sudden changes in charging and discharging power; : Weighting coefficient, with a value range of [0.1, 0.5], which balances the control precision and the intensity of fluctuation suppression.

[0046] ① Original control loss item The combined deviation between voltage and power is calculated using the mean square error: ; in, Target charging voltage for supercapacitors Real-time terminal voltage of the supercapacitor; Target charge / discharge power, Real-time charging and discharging power; , The weighting coefficients for voltage deviation and power deviation satisfy the following conditions: + =1; Mean squared error calculation function.

[0047] ② High-frequency fluctuation penalty item The high-frequency fluctuation component of the power is extracted by first-order difference, and the maximum value of the fluctuation amplitude within the sliding window is taken as the penalty term. ; in, : The power change in the t-th control cycle; , : Charge / discharge power of the current cycle and the previous cycle; k: Sliding window length, taken as 5~10 control cycles.

[0048] (2) Optimize control logic

[0049] Within each control cycle, the power conversion system aims to minimize the total loss function by using an optimization algorithm to find the optimal charging and discharging power command and control the bidirectional DC-DC converter to adjust the duty cycle. During charging, high-frequency sudden changes in power generation caused by fluctuations in vehicle speed are suppressed, and the internal thermal stress impact of the supercapacitor is reduced. During the discharge process, the output power curve is smoothed to reduce the power impact on the traction bus. It works in conjunction with an overvoltage protection module throughout the process to form a double safety protection.

[0050] In a specific embodiment, taking the installation project of an inertial energy recovery and storage system for a certain type of urban rail transit as an example, the above functions are verified. The basic system parameters are as follows: Overhead contact line rated voltage: DC1500V, allowable fluctuation range: [1000V, 1800V]; Supercapacitor rated voltage: 750V, overvoltage protection limit Rated capacity 50F; Rated power of the power conversion system: 200kW, control cycle: 10ms; Train operating conditions: inter-station coasting speed 30~120km / h, corresponding to power generation fluctuation range of 30~180kW.

[0051] Example 1: Verification of Adaptive Smoothing of Power Grid Fluctuations

[0052] Data from the train's taxiing phase before entering the station was selected. After initial screening using MIC and XGBoost, three core features were retained: historical contact network voltage, traction power, and supercapacitor SOC (cumulative importance percentage of 92.3%).

[0053] Take confidence level Based on kernel density estimation, the 95% confidence interval for the contact network voltage in the next 1 second is [1620V, 1780V], with the upper boundary approaching the grid's allowable upper limit of 1800V. The smoothing module reduces the original 150kW charging power to 110kW, and after adjustment, the predicted voltage confidence interval falls back to [1540V, 1690V], which is completely within the safe range, effectively avoiding overvoltage impact on the train control system.

[0054] Example 2: Verification of Optimized Charge and Discharge Control

[0055] Set the parameters for the loss function: The sliding window length k=8. Comparison of traditional constant power charging and optimized control effects: In the traditional mode, fluctuations in vehicle speed cause the maximum single change in charging power to reach 45kW / 10ms, resulting in large fluctuations in capacitor thermal stress. After optimization and control, the maximum variation in charging power is limited to within 12kW / 10ms, the high-frequency fluctuation suppression rate reaches 73%, the cycle life of the supercapacitor is expected to be improved by more than 25%, and the average charging efficiency is maintained at more than 94%, with no significant efficiency loss.

[0056] In conjunction with basic protection functions, when the supercapacitor voltage rises to the upper limit of 825V, the vehicle controller disconnects the power generation unit within 10ms to stop energy storage; when overload or short circuit faults are triggered, the hardware protection circuit cuts off the main circuit within 5ms to ensure the electrical safety of the vehicle.

[0057] Furthermore, the inertial kinetic energy harvesting mechanism includes: a clutch assembly and a planetary gear transmission mechanism; The clutch assembly is controlled by the vehicle controller; During the train startup phase, the clutch disengages, and the inertial kinetic energy capture mechanism idles. During coasting, the clutch engages, and the wheel axle drives the planetary gear mechanism to rotate. During emergency braking, the clutch disengages immediately without interfering with the original vehicle braking system.

[0058] Furthermore, the vehicle controller divides the speed threshold: when the train's operating speed is greater than 5 km / h, it enters the recyclable range; during the 0-5 km / h start-up phase, the clutch remains disengaged to avoid the additional resistance of wheel-rail static friction at 0-5 km / h and reduce start-up energy consumption.

[0059] Furthermore, the vehicle controller is configured with a priority logic hierarchy: emergency braking > train start-up energy storage and charging > energy recovery during coasting.

[0060] Furthermore, the entire energy storage assembly is located in the empty space at the bottom of the carriage, without the need to cut or modify the main structure of the car body; it is only connected to the wheel axle through a flange structure, and can be used for later installation on existing trains or as a factory-fitted component for new trains.

[0061] Furthermore, a method for recovering and storing train inertial energy, such as... Figure 1 As shown, it includes: Step 1, Train acceleration phase: The vehicle controller disengages the clutch, the inertial energy capture mechanism stops working, and the train runs entirely on the power of the overhead contact line. Step 2, High-speed coasting stage: When the vehicle speed is >5km / h, the clutch engages, the wheel axle drives the planetary gear mechanism to rotate, and mechanical energy is converted into electrical energy and stored in the supercapacitor energy storage cabinet. Step 3, Train restarts: The supercapacitor energy storage cabinet prioritizes releasing electrical energy to assist the traction motor in doing work, reducing the instantaneous load on the power grid; Step 4, Emergency Braking: The vehicle controller receives the braking signal, the clutch quickly disengages, the supercapacitor energy storage cabinet stops working, and the original vehicle braking system independently completes the braking. Step 5, Low speed range of 0-5km / h: The energy storage system remains dormant throughout the entire process, overcoming the static and dynamic friction resistance during startup, allowing the train to start smoothly.

[0062] In a specific embodiment, taking the installation project of an inertial energy recovery and storage system for a certain type of urban rail transit as an example, the speed matching control is performed using the above method, and the matching process of system parameters with different operating conditions is as follows: Basic boundary parameters: Train wheel rolling radius r = 0.45m; fixed transmission ratio of planetary gear transmission mechanism. =2.4, transmission efficiency Clutch assembly transmission efficiency The speed matching unit is set with 3 speed levels, and the parameters are shown in Table 1 below: Table 1

[0063] The high-efficiency speed range of the power generation unit is [1600, 3200] r / min, and the peak efficiency range is [2000, 2800] r / min, corresponding to the electromechanical conversion efficiency. Peak efficiency is 0.95.

[0064] Operating Condition 1: Low-speed coasting (v=30km / h)

[0065] 1. Calculate the wheel and axle speed: ; 2. Calculate the generator speed by iterating through the gears: 1st gear overall gear ratio ,\ Items below the lower limit of the efficient range are excluded. 2nd gear overall gear ratio , Items below the lower limit of the efficient range are excluded. 3rd gear overall gear ratio , It is still below the lower limit of the efficient range.

[0066] Control logic: The current vehicle speed has not entered the optimal recovery range, so it remains in 3rd gear and ready to start full power recovery once the vehicle speed increases and the generator speed enters the high-efficiency range.

[0067] Operating Condition 2: Medium-speed coasting (v=70km / h)

[0068] 1. Wheel and axle speed: ; 2. Calculation of generator speed and overall efficiency at each speed setting: Gear 1: Items below the high-efficiency range are excluded. 2nd gear: Falling into the high-efficiency range, corresponding to Overall efficiency ; 3rd gear: Falling into the peak efficiency range, corresponding to Overall efficiency .

[0069] Control logic: The vehicle controller selects level 3 as the working level, the power generation unit operates in the peak efficiency range, and the total energy recovery efficiency reaches the optimal level.

[0070] Operating Condition 3: High-speed coasting (v=120km / h)

[0071] 1. Wheel and axle speed: ; 2. Calculation of generator speed and overall efficiency at each speed setting: 3rd gear: Items exceeding the upper limit of the efficient range are discarded. 2nd gear: Approaching the upper limit of the efficient range, corresponding to Overall efficiency ; Gear 1: Falling into the high-efficiency range, corresponding to Overall efficiency .

[0072] Control logic: The vehicle controller switches to level 1 to stabilize the speed of the generator unit within the high-efficiency range, preventing the generator unit from running at overspeed at high speeds, while ensuring high energy recovery efficiency.

[0073] Through the above-mentioned multi-stage variable speed matching control, the power generation unit can maintain a high-efficiency working state in a wide coasting speed range of 30~120km / h, and the average total efficiency of the energy recovery link is stable at over 85%, which is more than 18% higher than the recovery efficiency of the fixed transmission ratio scheme.

[0074] In a specific embodiment, the vehicle controller reads the train's operating speed in real time: 1. Low-speed start-up phase: In the low-speed start-up range of 0-5km / h, the clutch should always be disengaged to prevent increased static friction resistance; 2. In high-speed coasting mode, when the train speed is >5km / h, the vehicle controller controls the clutch assembly to engage, and the wheel axle drives the planetary gear transmission mechanism to rotate. The speed matching unit adjusts the transmission ratio according to the real-time speed of the train, and transmits the mechanical energy of the wheel axle to the power generation unit. After the electrical energy is regulated and filtered by the power conversion control system, it is stored in the supercapacitor energy storage cabinet. 3. Train restarts and accelerates: The supercapacitor releases its energy first to assist the traction motor in doing work, reducing the train's energy intake from the overhead contact line and lowering the instantaneous load on the power grid; once the supercapacitor has released all its energy, the train then relies entirely on the power grid for power. 4. Emergency braking condition: When the original vehicle control system sends a braking signal, the vehicle controller immediately controls the clutch to disengage, the inertial kinetic energy capture mechanism stops working, and the train relies entirely on the brake pads for braking, with the original vehicle braking system not subject to any interference. 5. When the supercapacitor voltage reaches the set upper limit, the vehicle controller automatically stops generating electricity to avoid overvoltage damage to the energy storage devices; when the train's grid voltage fluctuates, the power conversion control system automatically adjusts the output power to ensure the safe operation of the original vehicle equipment.

[0075] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0076] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A train inertial energy recovery and storage system, characterized in that, include: Inertial kinetic energy harvesting mechanism, speed matching unit, power generation unit, power conversion control system, supercapacitor energy storage cabinet and vehicle controller; The inertial kinetic energy harvesting mechanism is connected to the train wheel axle drive, and the vehicle controller is connected to the inertial kinetic energy harvesting mechanism, the speed matching unit, the power generation unit, the power conversion control system, and the supercapacitor energy storage cabinet respectively. The vehicle controller is connected to the train vehicle control system and distinguishes between high-speed coasting, emergency braking, and acceleration phases based on the train speed signal. When the train is in a high-speed coasting condition, the vehicle controller activates the inertial kinetic energy capture mechanism. The mechanical energy output by the rotation of the wheels is transmitted to the power generation unit after being adjusted by the speed matching unit. The electrical energy output by the power generation unit is stored in the supercapacitor energy storage cabinet after being stabilized and filtered by the power conversion control system. When the train is in an emergency braking situation, the vehicle controller quickly cuts off the inertial energy capture mechanism and the power generation unit, and the train relies on the brake pads for braking. When the train is in the acceleration phase, the vehicle controller controls the supercapacitor energy storage cabinet to release electrical energy, which, in conjunction with the traction motor, drives the train forward.

2. The train inertial energy recovery and storage system according to claim 1, characterized in that, The speed matching unit has multiple speed gears, each gear corresponding to a fixed transmission ratio; The vehicle controller collects the real-time running speed of the train and, based on the efficiency calculation model of multi-stage transmission series, solves the total energy recovery efficiency and the operating speed of the power generation unit under different gears. The speed ratio is dynamically adjusted with the rated high-efficiency speed range of the power generation unit as a constraint. The higher the train's operating speed, the smaller the corresponding total transmission ratio of the system, ensuring that the input speed of the power generation unit is kept within the high-efficiency power generation range, thus maximizing the energy recovery efficiency during the full high-speed coasting phase.

3. The train inertial energy recovery and energy storage system according to claim 2, characterized in that, The speed matching unit is equipped with multiple sets of speed and torque detection modules, which are respectively arranged at the wheel axle input end, the planetary gear transmission mechanism output end, the speed matching unit output end and the power generation unit input end; The vehicle controller has a built-in transmission efficiency calculation module that uses a data-driven efficiency prediction method to quantitatively evaluate the energy recovery link and combines real-time vehicle speed and detection signals to achieve optimal matching of gears.

4. The train inertial energy recovery and storage system according to claim 1, characterized in that, The power conversion control system has built-in overvoltage protection module, overload protection module and short circuit protection module; When the supercapacitor voltage reaches the set upper limit, the vehicle controller disconnects the power generation unit and stops energy storage; When voltage fluctuations occur in the train's power grid, the output power is adjusted to avoid impacting the train's vehicle control system.

5. The train inertial energy recovery and storage system according to claim 4, characterized in that, The power conversion control system also includes a built-in adaptive grid fluctuation smoothing module. The adaptive power grid fluctuation mitigation module collects multi-source operating features in real time, including contact network voltage, train traction power, supercapacitor state of charge, train speed and braking status. It uses the MIC maximum information coefficient to quantify the nonlinear correlation between each feature and power grid voltage fluctuation, and combines the XGBoost algorithm to output the importance value of each feature to voltage fluctuation. Core features are then selected to form the power grid fluctuation prediction input feature set. A voltage fluctuation probability prediction model is constructed based on the input feature set. The probability distribution and confidence interval of the future short-term grid voltage are obtained through kernel density estimation. The charging and discharging power commands of the power conversion system are dynamically adjusted according to the upper and lower limits of the confidence interval to smooth out the contact network voltage fluctuations and avoid overvoltage and undervoltage impacts on the train vehicle control system.

6. The train inertial energy recovery and storage system according to claim 4, characterized in that, The power conversion control system also includes a built-in charge and discharge optimization control module; The charge-discharge optimization control module constructs an improved loss function as the optimization target of power control. The original loss term is the mean square error of the supercapacitor terminal voltage deviation and the charge-discharge power command deviation, and the auxiliary loss term is the penalty term for the high-frequency fluctuation component of the charge-discharge power. The total loss function is formed by combining the weighted coefficients. Throughout the entire energy recovery and release process, the optimal charging and discharging power command is solved in real time with the goal of minimizing the total loss function. This suppresses high-frequency power fluctuations, reduces the sudden change in the charging and discharging rate of the supercapacitor while ensuring energy conversion efficiency, delays capacitor aging, and extends the service life of the energy storage system.

7. The train inertial energy recovery and storage system according to claim 1, characterized in that, The inertial kinetic energy harvesting mechanism includes: a clutch assembly and a planetary gear transmission mechanism; The clutch assembly is controlled by the vehicle controller; During the train startup phase, the clutch disengages, and the inertial kinetic energy capture mechanism idles. During coasting, the clutch engages, and the wheel axle drives the planetary gear mechanism to rotate. During emergency braking, the clutch disengages immediately without interfering with the original vehicle braking system.

8. The train inertial energy recovery and storage system according to claim 1, characterized in that, The vehicle controller divides the speed threshold: when the train's operating speed is greater than 5 km / h, it enters the recyclable zone; during the 0-5 km / h start-up phase, the clutch remains disengaged to avoid the additional resistance of wheel-rail static friction at 0-5 km / h and reduce start-up energy consumption.

9. A train inertial energy recovery and storage system according to claim 1, characterized in that, The vehicle controller is configured with a priority logic hierarchy: emergency braking > train start-up energy storage and charging > energy recovery during coasting.

10. A method for recovering and storing inertial energy in trains, characterized in that, include: Step 1, Train acceleration phase: The vehicle controller disengages the clutch, the inertial energy capture mechanism stops working, and the train runs entirely on the power of the overhead contact line. Step 2, High-speed coasting stage: When the vehicle speed is >5km / h, the clutch engages, the wheel axle drives the planetary gear mechanism to rotate, and mechanical energy is converted into electrical energy and stored in the supercapacitor energy storage cabinet. Step 3, Train restarts: The supercapacitor energy storage cabinet prioritizes releasing electrical energy to assist the traction motor in doing work, reducing the instantaneous load on the power grid; Step 4, Emergency Braking: The vehicle controller receives the braking signal, the clutch quickly disengages, the supercapacitor energy storage cabinet stops working, and the original vehicle braking system independently completes the braking. Step 5, Low speed range of 0-5km / h: The energy storage system remains dormant throughout the entire process, overcoming the static and dynamic friction resistance during startup, allowing the train to start smoothly.

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