Flywheel and motor hybrid drive discrete gravity energy storage system and control method

Abstract

This application relates to a discrete gravity energy storage system and control method with a hybrid flywheel and motor drive. The system employs a three-port differential planetary gearbox. The three-port differential connection structure between the three-port differential planetary gearbox, the main drive motor, and the flywheel energy storage module avoids the synchronization of flywheel and load speeds in traditional rigid transmissions. This allows the flywheel energy storage module to reduce its speed under the target torque at the sun gear end during the acceleration and start-up phase of a heavy load, releasing the stored rotational kinetic energy. This energy is transmitted to the planetary carrier end via the three-port differential planetary gearbox, providing high-frequency transient compensation torque to the load. This torque is used to handle the main high-frequency transient torque demand during the load start-up phase, thus mitigating the mechanical wear caused by frequent starts and stops of heavy loads on the mechanical planetary carrier output system and the voltage flicker on the grid side.

Description

Technical Field

[0001] This application relates to the field of gravity energy storage system technology, and in particular to a discrete gravity energy storage system and control method that uses a flywheel and motor hybrid drive. Background Technology

[0002] With the construction of new power systems, gravity energy storage systems based on discrete media have attracted widespread attention. These systems mainly convert electrical energy into gravitational potential energy by vertically lifting and lowering heavy objects using lifting equipment. However, in actual operation, existing discrete media gravity energy storage systems involve frequent grabbing, acceleration, deceleration, positioning, and release of heavy objects, causing the drive system to operate under intermittent, pulse-like impact load conditions for extended periods.

[0003] Existing technologies typically employ solutions such as single-motor direct drive, parallel flywheel on the electrical side, coaxial mechanically coupled flywheel, or staged flywheel connection via clutch and transmission mechanisms. The single-motor direct drive solution requires the main drive motor to directly bear the starting impact of heavy loads, easily leading to motor selection based on peak power redundancy. The parallel flywheel solution on the electrical side primarily smooths power fluctuations on the electrical side, making it difficult to share the start-stop impact at the front end of the mechanical transmission chain. The coaxial mechanically coupled flywheel solution has a fixed speed ratio limitation, making it difficult for the flywheel to independently decelerate and release energy during the acceleration and lifting phase of heavy loads, and potentially increasing the equivalent inertial load on the main drive motor. While the staged flywheel connection via clutch and transmission mechanisms can release flywheel kinetic energy during startup, it carries risks related to power switching, speed matching, and mechanical impact. Therefore, existing solutions still struggle to simultaneously achieve flywheel decoupling from the load actuator speed, continuous participation of the flywheel's mechanical side in transient torque compensation, and reduced peak power selection requirements for the main drive motor. Frequent start-stop impacts may still exacerbate mechanical wear and cause voltage fluctuations on the grid side. Summary of the Invention

[0004] In view of this, in order to at least partially improve the above-mentioned problems, this application provides a discrete gravity energy storage system and control method with a flywheel and motor hybrid drive.

[0005] Firstly, this application provides a discrete gravity energy storage system driven by a hybrid flywheel and motor, comprising: A three-port differential planetary gearbox, comprising a ring gear, a sun gear, and a planet carrier; A main drive motor, the output shaft of which is connected to the gear ring drive, is used to provide steady-state driving torque for the discrete gravity energy storage system; A flywheel energy storage module, wherein the output shaft of the flywheel energy storage module is connected to the sun gear; A cable, one end of which is connected to a heavy object lifting actuator, and the other end of which is connected to a discrete gravity load; The end of the load lifting actuator away from the cable is connected to the planetary carrier transmission, and is used as a power output end to drive the cable to lift or lower the discrete gravity load. A collaborative controller is electrically connected to the main drive motor and the flywheel energy storage module, respectively. It is used to dynamically adjust the torque distribution according to the load state of the heavy object lifting actuator. By utilizing the differential characteristics of the three-port differential planetary gearbox, it realizes non-rigid synchronous differential coupling between the flywheel energy storage module and the heavy object lifting actuator. During the acceleration period of the discrete gravity load, the flywheel energy storage module passively decelerates and releases rotational kinetic energy by utilizing the differential action of the three-port differential planetary gearbox. The collaborative controller is also used to obtain the total load torque at the planetary carrier end, decompose the total load torque into low-frequency load torque and high-frequency load torque, and generate the target torque at the ring gear end and the target torque at the sun gear end based on the torque balance relationship of the three-port differential planetary gearbox, so that the main drive motor mainly undertakes the low-frequency steady-state torque and the flywheel energy storage module mainly undertakes the high-frequency transient torque.

[0006] In one embodiment, the flywheel energy storage module includes a vacuum housing, and a flywheel rotor, a flywheel motor, a radial permanent magnet bearing, and an axial permanent magnet bearing disposed inside the vacuum housing; The flywheel motor and the flywheel rotor are connected via the same shaft, and the output shaft of the flywheel motor is connected to the sun gear; The radial permanent magnet bearing provides radial support for the flywheel rotor and the shaft, and the axial permanent magnet bearing provides axial support for the flywheel rotor and the shaft.

[0007] In one embodiment, it also includes a DC bus and a grid-connected bidirectional converter; Both the main drive motor and the flywheel motor are connected to the DC bus through corresponding motor-side converter units; The DC bus is connected to the external power grid through the grid-connected bidirectional converter to form an energy interaction network.

[0008] In one embodiment, the cooperative controller is internally configured with a torque distribution module, which is used for: Obtain the total load torque and virtual inertia coefficient transmitted to the output end of the planetary carrier; The low-frequency load torque is obtained by extracting the steady-state components in the total load torque using a low-pass filter. The high-frequency load torque is obtained by extracting the fast abrupt change component in the total load torque using a high-pass filter. The low-frequency target output torque of the planetary carrier is generated based on the low-frequency load torque, wherein the generation formula is: T * c,L =T load,L ; Among them, T * c,L For low-frequency target output torque, T load,L For low-frequency load torque; Obtain the measured angular velocity of the planetary carrier, and generate the high-frequency target output torque of the planetary carrier based on the high-frequency load torque, the virtual inertia coefficient, and the measured angular velocity, wherein the generation formula is: ; Among them, T * c,H For the high-frequency target output torque, T load,H For high-frequency load torque, J vir ω is the virtual inertia coefficient. c The measured angular velocity of the planetary carrier. This is the derivative of the measured angular velocity.

[0009] In one embodiment, the torque distribution module is further configured to: The target torque at the gear end of the gear ring is mapped based on the low-frequency load torque and the high-frequency target output torque, wherein the mapping formula is: ; Among them, T * r Let λ be the target torque at the ring gear end, k be the ratio of the number of teeth on the ring gear to the number of teeth on the sun gear, and λ be the value of the target torque at the ring gear end. r The high-frequency sharing coefficient of the main drive motor; The target torque at the sun gear end is mapped based on the low-frequency load torque and the high-frequency target output torque, wherein the mapping formula is: ; Among them, T * s λ represents the target torque at the sun gear end. s The high-frequency sharing coefficient of the flywheel energy storage module; The cooperative controller is used to control the main drive motor according to the target torque at the gear ring end, and to control the flywheel energy storage module according to the target torque at the sun gear end.

[0010] In one embodiment, the load lifting actuator is provided with a tension detection unit, which is used to acquire the real-time tension, equivalent winding radius and transmission efficiency corresponding to the discrete gravity load in real time. The collaborative controller is also equipped with a load observation and verification module, which is used to obtain the real-time operating parameters of the main drive motor and the flywheel motor, and estimate the model observation load torque transmitted to the output end of the planetary carrier online based on the real-time operating parameters. It is also used to calculate the directly measured load torque based on the real-time tension, the equivalent winding radius, and the transmission efficiency; It is also used to calculate the difference between the model-observed load torque and the directly measured load torque, and to determine whether the absolute value of the difference is less than or equal to a preset deviation threshold. If the load torque is less than or equal to the preset deviation threshold, the model observed load torque is checked and corrected at low frequency based on the directly measured load torque, and the model observed load torque after low-frequency check and correction is taken as the total load torque. If the deviation exceeds the preset deviation threshold and continues to reach the preset control cycle number, the tension detection unit is determined to be abnormal. The collaborative controller stops using the direct measurement of load torque for verification and switches to using the model observation of load torque based solely on the real-time operating parameters as the basis for output control.

[0011] In one embodiment, the collaborative controller is further configured with an active pre-management module based on model predictive control: The active pre-management module has a built-in discrete-time state-space model of the discrete gravity energy storage system. The active pre-management module is used to obtain the operating timetable and the predicted load torque value within a preset time period issued by the external control system. It is also used to dynamically generate a flywheel reference speed based on the running schedule, and to use the flywheel reference speed as the target trajectory; It is also used to solve for the optimal torque distribution sequence within multiple control cycles in a future preset time period based on the discrete-time state-space model, with the joint optimization objectives of minimizing the peak torque of the main drive motor and minimizing the tracking error of the actual rotational speed of the flywheel energy storage module on the target trajectory, wherein the cost function J of the discrete-time state-space model is: ; Where N is the total number of control cycles, t is the current sampling time, i is the future step size index in the prediction time domain, and T m (t+i) represents the torque of the main drive motor at step t+i within a preset time period, ω f (t+i) represents the actual rotational speed of the flywheel energy storage module at step t+i within a preset future time period; ω ref (t+i) is the reference speed of the flywheel at step t+i, T m,N ω is the rated torque of the main drive motor.f,N The rated operating speed of the flywheel energy storage module is given by q, and r is a preset weighting coefficient for the main drive motor and the flywheel energy storage module, respectively, and satisfies q+r=1. The process of solving the optimal torque distribution sequence satisfies the main drive motor torque constraint, flywheel motor torque constraint, flywheel speed constraint, load-side speed constraint, and torque change rate constraint.

[0012] In one embodiment, the proactive pre-management module is further configured to retrieve the predicted load torque value within the future preset time period according to the operating schedule; When a positive step is detected in the predicted load torque value, it is determined that the current time is within a preset time window before the lifting action of the heavy object; when a negative step is detected in the predicted load torque value, it is determined that the current time is within a preset time window before the lowering action. If the current time is within a preset time window before the lifting of the heavy object, the active pre-management module only extracts the first time step torque command in the optimal torque distribution sequence as an electric torque command to drive the flywheel energy storage module to accelerate in advance; If it is within the preset time window before the lowering action, the active pre-management module only extracts the first time step torque command in the optimal torque distribution sequence as a braking torque command to make the flywheel energy storage module slow down in advance.

[0013] This application also provides a control method for a discrete gravity energy storage system driven by a flywheel and motor hybrid as described in any of the preceding claims, executed by the cooperative controller, the method comprising: The load status of the lifting actuator is obtained to extract the total load torque, low-frequency load torque, and high-frequency load torque; Based on the torque balance relationship of the three-port differential planetary gearbox, the target torque at the ring gear end and the target torque at the sun gear end are mapped and generated to dynamically adjust the torque distribution between the main drive motor and the flywheel energy storage module. The system obtains the operating timetable and load torque prediction value issued by the external control system, dynamically generates the flywheel reference speed as the target trajectory based on the operating timetable, and performs optimization solution based on the preset discrete time state space model and cost function to obtain the optimal torque distribution sequence. Utilizing the rolling time domain control principle, when determining that the current time window is before the lifting or lowering of the heavy object, only the first time step torque command in the optimal torque distribution sequence is extracted as the actual control output. This drives the flywheel energy storage module to increase speed in advance before lifting, or causes the flywheel energy storage module to decrease speed in advance before lowering.

[0014] In one embodiment, before obtaining the load state of the load lifting actuator to extract the total load torque, the method further includes: The real-time operating parameters of the main drive motor and the flywheel motor in the flywheel energy storage module are obtained, and the model observation load torque transmitted to the output end of the planetary carrier is estimated online. Obtain real-time tension, equivalent winding radius, and transmission efficiency; calculate the directly measured load torque. Calculate the absolute value of the difference between the model-observed load torque and the directly measured load torque, and determine whether the absolute value is less than or equal to a preset deviation threshold. If so, the model observed load torque is parameter-corrected based on the directly measured load torque, and the corrected model observed load torque is used as the total load torque; If the deviation exceeds the preset threshold and continues to reach the preset control cycle number, the lifting actuator is determined to be abnormal. The collaborative controller stops using the direct measurement of load torque for verification and switches to using the model observation of load torque based solely on the real-time operating parameters as the basis for output control.

[0015] Beneficial Effects: This application employs a three-port differential planetary gearbox, which includes a ring gear, a sun gear, and a planet carrier. The output shafts of the main drive motor and the flywheel energy storage module are connected to the ring gear and the sun gear, respectively, and the load lifting actuator is connected to the planet carrier. This three-port differential connection structure of the three-port differential planetary gearbox, the main drive motor, and the flywheel energy storage module avoids the synchronization of flywheel and load speeds in traditional rigid transmissions. During the acceleration and start-up phase of the load, the flywheel energy storage module reduces its speed under the target torque at the sun gear end and transfers the stored rotational kinetic energy to the planet carrier end via the three-port differential planetary gearbox. This provides high-frequency transient compensation torque for the load, bearing the main high-frequency transient torque demand during the load start-up phase. This effectively mitigates the mechanical wear on the planet carrier output end caused by frequent starts and stops of the load, as well as the voltage flicker on the power grid side. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of the structure of a discrete gravity energy storage system driven by a flywheel and a motor according to an embodiment of this application.

[0017] Figure 2 This is a schematic diagram of the structure of a three-port differential planetary gearbox of a discrete gravity energy storage system driven by a flywheel and a motor according to an embodiment of this application.

[0018] Figure 3 This is a flowchart illustrating a control method for a discrete gravity energy storage system driven by a hybrid flywheel and motor, according to one embodiment of this application.

[0019] Reference numerals in the attached diagram: 1. Main drive motor; 2. Flywheel energy storage module; 3. Radial permanent magnet bearing; 4. Flywheel motor; 5. Axial permanent magnet bearing; 6. Flywheel rotor; 7. Vacuum housing; 8. Three-port differential planetary gearbox; 9. Heavy lifting actuator; 10. Cable; 11. Discrete gravity load; 12. Coordination controller; 13. DC bus; 14. Main drive motor output shaft; 15. Flywheel motor output shaft; 16. Ring gear; 17. Sun gear; 18. Planetary gears; 19. Planetary carrier. Detailed Implementation

[0020] The terms "first," "second," and "third," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the term "comprising," and any variations thereof, is intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or modules is not limited to the listed steps or modules, but may optionally include steps or modules not listed, or may optionally include other steps or modules inherent to these processes, methods, products, or apparatuses.

[0021] Please see Figures 1-3This application provides an embodiment of a discrete gravity energy storage system with a hybrid flywheel and motor drive, including a main drive motor 1, a three-port differential planetary gearbox 8, a flywheel energy storage module 2, a cable 10, a load lifting actuator 9, and a co-controller 12. The three-port differential planetary gearbox 8 includes a ring gear 16, a sun gear 17, a planet carrier 19, and multiple planet gears 18 meshing between the ring gear 16 and the sun gear 17. The main drive motor output shaft 14 of the main drive motor 1 is connected to the ring gear 16. In this embodiment, the main drive motor 1 is preferably a high-power, low-speed, high-torque three-phase permanent magnet synchronous motor, used to provide the fundamental steady-state drive torque during the steady-state operation of the discrete gravity load 11. The flywheel motor output shaft 15 of the flywheel motor 4 inside the flywheel energy storage module 2 is connected to the sun gear 17 at high speed and low torque, serving as a high-frequency transient auxiliary power source for the system, used to smooth out intermittent, pulse-like impact loads generated during frequent start-stop operations. The end of the load-lifting actuator 9 (e.g., a winch drum) furthest from the cable 10 is connected to the planetary carrier 19. This is the power output end of the entire system's power transmission chain. Exemplarily, this connection can be achieved through a coupling, spline, gear pair, or reduction gear mechanism. Through this connection method, the main drive motor 1, flywheel motor 4, and load-lifting actuator 9 correspond to the gear ring 16, sun gear 17, and planetary carrier 19, respectively, thus forming a three-port differential coupling structure.

[0022] Cable 10 is a flexible cable, such as a high-strength steel wire rope. One end is wound and fixed to the lifting actuator 9, and the other end extends downward to connect to the discrete gravity load 11, which can be a concrete energy storage block or a metal module. When the lifting actuator 9 rotates, the flexible cable 10 enables the vertical lifting and lowering of the discrete gravity load 11, thereby completing the conversion of electrical energy into gravitational potential energy. The cooperative controller 12 is electrically connected to the main drive motor 1 and the flywheel energy storage module 2, respectively. The cooperative controller 12 can adopt a dual DSP structure or a microcontroller, and is responsible for executing a high-bandwidth electromechanical cooperative allocation algorithm.

[0023] To address the problem in existing technologies where the flywheel must accelerate synchronously during load acceleration, resulting in an inability to release kinetic energy, this embodiment breaks the physical limitation of synchronized rotational speed by defining the constraints and balance relationships of the three-port differential planetary gearbox 8's three-port kinematics. Specifically: For the three-port differential planetary gearbox 8, let the angular velocities of the sun gear 17, ring gear 16, and planet carrier 19 be ω s ω r and ω c The corresponding port torques are T s T r and T c Define the number of teeth on the sun gear 17 as Z. sThe number of teeth on gear ring 16 is Z. r And define the tooth ratio constant k=Z r / Z s According to the principle of involute planetary gear transmission, the three-port kinematic constraint relationship (Equation 1) is expressed as: Z s ω s +Z r ω r =(Z s +Z r )ω c ; That is, ω s +kω r =(1+k)ω c ; Under ideal conditions where gear meshing mechanical losses are neglected, based on the conservation of active power and torque balance, the three-port torque balance relationship (Equation 2) is expressed as follows: T r :T s :T c =k:1:-(1+k); Among them, T in torque ratio c The corresponding coefficient is negative, which means that when the system outputs energy, the planet carrier 19 acts as the power output port, and the direction of its torque is opposite to the direction of the torque at the energy input end of the ring gear 16 and the sun gear 17.

[0024] In existing coaxial rigid designs, both the flywheel and the main drive motor share a single shaft. This forces the load speed to increase during acceleration, and the flywheel speed must also increase synchronously. However, according to the kinetic energy theorem, the flywheel must decelerate to release kinetic energy. This results in the flywheel's inability to release energy during the crucial acceleration phase, when torque compensation is most needed. In fact, it may increase the equivalent inertial load the main drive motor needs to overcome during startup, thus increasing the peak torque requirement of the main drive motor.

[0025] This embodiment utilizes the constraint and balance relationships of the above formulas (1) and (2) to determine the output angular velocity ω of the planetary carrier 19 when the heavy object starts accelerating. c Starting from zero, the main drive motor 1 is controlled to drive the gear ring 16 with rated steady-state torque to maintain a low main speed, i.e., angular velocity ω. r At this time, the flywheel energy storage module 2 connected to the sun gear 17 can reduce its speed and release rotational kinetic energy (i.e., ω) under the action of the target torque at the sun gear end while the load accelerates. s(Descending). The rotational kinetic energy released by the flywheel energy storage module 2 is transmitted to the three-port differential planetary gearbox 8 through the sun gear 17, and together with the driving torque provided by the main drive motor 1 at the planet carrier 19 end, it forms the output torque to compensate for the static friction torque and transient acceleration torque requirements of the discrete gravity load 11 during the start-up phase.

[0026] Through the three-port differential connection structure that connects the main drive motor 1, flywheel energy storage module 2, and heavy load lifting actuator 9 to the gear ring 16, sun gear 17, and planetary carrier 19 respectively, this embodiment utilizes the differential characteristics of the three-port differential planetary gearbox 8 to decouple the physical speed of the flywheel energy storage module 2 from that of the main drive motor 1. During the acceleration period of the discrete gravity load 11, the flywheel energy storage module 2 uses the differential action of the three-port differential planetary gearbox 8 to decelerate and release rotational kinetic energy, thereby providing high-frequency transient compensation torque. This reduces the installed capacity requirement of the main drive motor 1 and mitigates the pulse impact caused by the start and stop of heavy loads on the mechanical transmission chain and the power grid. This achieves flexible acceleration start-up of a small-capacity motor driving a large impact load and reduces the need for redundant selection of the main drive motor based on transient peak load.

[0027] In one embodiment, to ensure the system's operational lifespan during high-frequency, minute-level energy storage and release cycles, the flywheel energy storage module 2 employs a non-mechanically contactable magnetic levitation vacuum assembly structure. Specifically, the flywheel energy storage module 2 includes a vacuum housing 7, and a fully enclosed flywheel rotor 6, flywheel motor 4, radial permanent magnet bearing 3, and axial permanent magnet bearing 5 housed within the vacuum housing 7. The flywheel motor 4 and the flywheel rotor 6 are coaxially connected via the same central shaft. The radial permanent magnet bearing 3 (distributed at both ends of the shaft) and the axial permanent magnet bearing 5 (located at the bottom of the shaft) work together to levitate the flywheel rotor 6 using magnetic repulsion, eliminating the contact friction of conventional mechanical bearings, greatly improving high-speed operational stability, and reducing no-load losses. The vacuum housing 7 is maintained at an ultra-low pressure by evacuation, reducing air friction losses and heat generation of the flywheel rotor 6 during high-speed rotation at tens of thousands of revolutions per minute.

[0028] On the electrical connection side, such as Figure 1 As shown, both the main drive motor 1 and the flywheel motor 4 are connected in parallel to the common DC bus 13 through their respective independent motor-side converter units (AC / DC controllable rectifier / inverter) with bidirectional power flow capability. The other end of the DC bus 13 is connected to the external power grid through a grid-connected bidirectional converter (grid-side inverter), forming a bidirectional energy interaction channel between the power grid, the DC bus, the main drive motor, and the flywheel motor. The flywheel motor 4 can operate in both the generator braking quadrant (converting the rotational kinetic energy of the flywheel rotor 6 into electrical energy to feed back to the bus) and the electric acceleration quadrant (absorbing electrical energy from the bus and converting it into mechanical energy for storage).

[0029] Specifically, the grid-connected bidirectional converter employs stator field-oriented current vector control based on a synchronous rotating coordinate system. Internally, the grid-connected bidirectional converter decouples the active current component for independently controlling active power and the reactive current component for independently controlling reactive power. When external grid voltage fluctuates, the power factor deviates from the preset range, or the system requires voltage support, the coordinating controller 12 dynamically adjusts the reactive current component within the remaining apparent capacity allowable by the grid-connected bidirectional converter. Simultaneously, the flywheel energy storage module 2 remains primarily responsible for buffering sudden changes in active power during the start-up and shutdown of heavy loads on the mechanical side. Thus, the system achieves coordinated control of active power surge shaving on the mechanical side and reactive power voltage support on the electrical side. Therefore, in this embodiment, the reactive power compensation function is completed by the grid-connected bidirectional converter, and the flywheel rotor 6 provides the mechanical kinetic energy reserve required for active power buffering, thereby improving grid-connected operation stability.

[0030] In one embodiment, the collaborative controller 12 is internally equipped with a torque distribution module. During the vertical lifting and lowering operation of the discrete gravity energy storage system, the lifting actuator 9 is frequently subjected to mechanical impacts from the discrete gravity load 11 at the moment of lifting off the ground or at the moment of deceleration and positioning, causing the total load torque transmitted to the output end of the planetary carrier 19 to exhibit obvious transient change characteristics. In order to reduce the impact of torque fluctuations caused by the repeated start and stop of the discrete gravity load 11 on the main drive motor 1, the power grid side, and the mechanical transmission chain, the torque distribution module first obtains the total load torque transmitted to the output end of the planetary carrier 19 and the preset virtual inertia coefficient J. vir The torque distribution module employs a frequency domain decomposition algorithm based on a first-order low-pass filter and a high-pass filter. It extracts the steady-state components from the total load torque using the low-pass filter to obtain the low-frequency load torque, and extracts the fast-change components from the total load torque using the high-pass filter to obtain the high-frequency load torque. To avoid discretization divergence in digital control when directly using continuous transfer functions, this embodiment transforms them into a specific first-order linear recursive formula. The calculation process is as follows: T load,L [n]=αT load,L [n-1]+(1-α)T load [n]; T load,H [n]=T load [n]-T load,L [n]; α = τ / (τ + T); Where n is the current sampling sequence number, T load [n] represents the total load torque input at the current time step, T load,L [n] represents the extracted low-frequency load torque, T load,H[n] represents the extracted high-frequency load torque, α represents the adaptive smoothing coefficient of the filter, τ represents the preset filter time constant, and T represents the fixed sampling control period of the cooperative controller 12 (preferably 100μs~1ms in this embodiment). Through this recursive formula, it is possible to extract the slowly changing low-frequency load torque and the high-frequency load torque containing transient impacts under the condition of meeting the requirements of sampling period and filter time constant.

[0031] Then, based on the low-frequency load torque, the low-frequency target output torque at the power output terminal of the planetary carrier 19 is generated, wherein the generation formula is: T* c,L =T load,L ; Among them, T* c,L For low-frequency target output torque, T load,L For low-frequency load torque; Simultaneously, the measured angular velocity ω of the planetary carrier 19 is obtained. c The high-frequency target output torque of the planetary carrier is generated based on the high-frequency load torque, the virtual inertia coefficient, and the measured angular velocity, wherein the generation formula is: ; Among them, T* c,H For the high-frequency target output torque, T load,H For high-frequency load torque, J vir ω is the virtual inertia coefficient. c The measured angular velocity of the planetary carrier. This is the derivative of the measured angular velocity. By introducing the derivative of the measured angular velocity, the virtual inertia coefficient J can be utilized. vir By actively constructing large inertial characteristics on the mechanical shaft system, the mechanical hard impact caused by sudden changes in the weight is softened. In other words, the large inertial characteristics are simulated on the mechanical shaft through control algorithms, so that the speed change tends to be gradual and the impact is reduced.

[0032] To prevent the flywheel energy storage module 2 from applying a high-frequency, large-pulse torque alone to the sun gear 17 side, which could lead to localized force imbalance inside the three-port differential planetary gearbox 8, the torque distribution module performs strict three-port torque feedforward dynamic mapping based on the planetary gear set dynamic balance constraints. Specifically, the target torque at the gear ring end is mapped based on the low-frequency load torque and the high-frequency target output torque, wherein the mapping formula is: ; Among them, T * r Let be the target torque at the ring gear end, which serves as the basis for the final control torque issued to the main drive motor 1; k is the ratio of the number of teeth on the ring gear to the number of teeth on the sun gear of the planetary gearbox; λ is... r The high-frequency sharing coefficient of the main drive motor; The target torque at the sun gear end is mapped based on the low-frequency load torque and the high-frequency target output torque, wherein the mapping formula is: ; Among them, T * s The target torque at the sun gear end serves as the basis for the final control torque issued to the flywheel motor in flywheel energy storage module 2; λ s Let be the high-frequency sharing coefficient of the flywheel energy storage module; wherein, to ensure decoupling and smoothing effects, the high-frequency sharing coefficient satisfies 0 ≤ λ. r ≤0.2 and λ s ≥0.8, and satisfying λ r +λ s =1.

[0033] The cooperative controller 12 is used to control the output torque of the main drive motor 1 according to the target torque at the gear ring end, and to control the output torque of the flywheel energy storage module 2 according to the target torque at the sun gear end.

[0034] In existing technologies, frequency converters are only connected in parallel on the DC bus side. The flywheel energy storage system and the gravity mechanical shaft system are physically independent. Therefore, the high-frequency step impact generated by the start and stop of heavy objects can directly impact the winch gearbox and cable without obstruction. This embodiment, through the aforementioned mapping formula, ensures that the main drive motor 1 primarily follows the smooth, low-frequency target output torque command, guaranteeing that the active power changes on the main drive motor 1 and the external power grid side are relatively slow, thus being shaped into a standard smooth trapezoidal wave and avoiding microgrid voltage flicker and fluctuations caused by frequent high-current impacts. Simultaneously, the high-frequency sharing coefficient λ of the flywheel energy storage module 2 is... s ≥0.8, while the value for the main drive motor 1 is 0≤λ. r With a torque of ≤0.2, the flywheel energy storage module 2, on the sun gear 17 side, undertakes more than 80% of the transient active power throughput and unloading of the high-frequency transient load through physical acceleration or deceleration. At the same time, through the synchronous micro-torque correction of the main drive motor 1 on the gear ring 16 side, the torque balance between the gear ring, sun gear, and planet gears inside the planetary gear set is dynamically maintained, thereby reducing the risk of local impact and fatigue damage to the planet gears caused by asymmetric transient torque changes, and realizing the dynamic protection of mechanical hardware by the control algorithm.

[0035] In harsh environments such as gravity storage mines or large power plants, directly installing conventional torque sensors can lead to problems such as easy impact damage and large zero-point drift. Therefore, this embodiment also includes a load observation and verification module within the collaborative controller 12. The heavy-load lifting actuator 9 is equipped with a tension detection unit, such as a pulley pin-type tension sensor. This tension detection unit is used to acquire the real-time tension corresponding to the discrete gravity load 11.F Current equivalent winding radius R And the system transmission efficiency η. It should be noted that the equivalent winding radius R is not a fixed value, but a precise value obtained by the cooperative controller 12 through dynamic multi-level correction based on the drum base radius, cable diameter, and the number of cable winding layers accumulated by the current multi-turn absolute encoder on the drum. The load observation and verification module is based on the real-time tension... F The equivalent winding radius R and the transmission efficiency η are used to calculate the directly measurable load torque T. load,m The calculation formula is as follows: T load,m =(F·R) / η; Meanwhile, the load observation and verification module is used to acquire the real-time operating parameters of the main drive motor 1 and the flywheel motor, including the three-phase stator real-time current, stator terminal voltage, and the actual physical speed fed back by the rotary encoder. Based on the real-time operating parameters, it uses the built-in first-order nonlinear disturbance observer or extended state observer to estimate the model observation load torque T transmitted to the output terminal of the planetary carrier 19 online. load,o .

[0036] In a simplified implementation, the model observes the load torque T. load,o It can also be obtained using the following formula: ; Among them, T c,drive The electromagnetic torques of the main drive motor 1 and the flywheel motor 4 are mapped based on the planetary gearbox gear ratio k and act together on the equivalent drive torque at the end of the planet carrier 19. c To calculate the viscous friction coefficient at the output end of planetary carrier 19, J c,eq To calculate the equivalent moment of inertia at the output of planetary carrier 19, ω c The measured angular velocity of planetary carrier 19.

[0037] Next, the difference between the model-observed load torque and the directly measured load torque is calculated, and it is determined whether the absolute value of the difference is less than or equal to a preset deviation threshold. For example, this preset deviation threshold is preferably 5% of the system's rated load torque. If it is less than or equal to the preset deviation threshold, it indicates that the sensor is not damaged and there is no noise exceeding the limit, and the directly measured signal is deemed reliable. Based on the directly measured load torque, the model-observed load torque is subjected to low-frequency verification and correction through low-pass slow proportional-integral feedback, and the model-observed load torque after low-frequency verification and correction is used as the total load torque for input, participating in micro-frequency domain decoupling. If it is greater than the preset deviation threshold and continues to reach a preset number of control cycles, the tension detection unit is determined to be abnormal, the collaborative controller stops using the directly measured load torque for verification, and switches to using only the model-observed load torque based on the real-time operating parameters as the output control basis. For example, if the calculated absolute value is greater than the preset deviation threshold and continues for more than 5 control cycles, the adaptive judgment tension detection unit has experienced a hardware disconnection or drift anomaly. The cooperative controller 12 immediately disconnects the dynamic verification loop and returns to the pure model observation load torque output control based on real-time operating parameters. This provides a high level of industrial-grade disturbance rejection and fault tolerance while ensuring the accuracy of active power peak shaving.

[0038] In one embodiment, the cooperative controller 12 is further configured with an active pre-management module based on model predictive control. The active pre-management module has a built-in discrete-time state-space model of the discrete gravity energy storage system. Let the control period be T, the prediction time domain be N, the current sampling time be t, and the i-th future sampling time in the prediction time domain be t+i, where i=1,2,...,N; The system state vector x(t) is defined as: x(t)=[ω f (t),ω L (t),θ L (t)] T ; Where, ω f (t) represents the actual angular velocity of the flywheel rotor, ω L (t) represents the equivalent angular velocity of the load lifting mechanism, θ L (t) represents the equivalent angular displacement of the load lifting mechanism. The load lifting mechanism can be a winch or a drum.

[0039] The control input vector u(t) is defined as u(t) = [T] m (t),T α (t)] T T m (t) represents the torque of the main drive motor at the current sampling time t, where T is the torque of the main drive motor. α (t) represents the electromagnetic torque output by the flywheel motor.

[0040] The disturbance is defined as the equivalent gravitational torque of the load: d(t)=T L (t); Among them, T L (t) is the load equivalent gravitational torque converted to the output end of the planetary carrier 19 during the lifting or lowering of the heavy object, which is an unknown quantity.

[0041] The corresponding discrete state equation for this model is: x(t+1)=A d x(t)+B d u(t)+E d T L (t); Among them, A d Let B be the state matrix of the system. d To control the input matrix, E d The perturbation input matrix; in, ; ;

[0042] Among them, J f B is the equivalent moment of inertia of the flywheel rotor. f B is the equivalent damping coefficient of the flywheel. L J is the equivalent damping coefficient on the load side. L η is the equivalent moment of inertia referred to the output terminal of the planetary carrier 19 from the load side. f η is the transmission efficiency from flywheel motor 4 to high-speed flywheel rotor 6. m The transmission efficiency from the main drive motor 1 to the load side, η c The equivalent coupling efficiency of the three-port differential planetary gearbox 8 acting on the load side.

[0043] After discretization using the forward Euler method, the above matrix equations are equivalent to the following system of difference equations, which are iteratively updated in real time by the controller: ; ; ; Among them, J f J is the equivalent moment of inertia of the flywheel rotor. L The equivalent moment of inertia referred to the output terminal of planetary carrier 19 from the load side, where T is the control period and B is the load side. f B is the equivalent damping coefficient of the flywheel. L η is the equivalent damping coefficient on the load side. f η is the transmission efficiency from flywheel motor 4 to high-speed flywheel rotor 6. mThe transmission efficiency from the main drive motor 1 to the load side, η c The equivalent coupling efficiency of the three-port differential planetary gearbox 8 acting on the load side; ω f (t+1) represents the actual angular velocity of the flywheel rotor at the (t+1)th sampling time, ω L (t+1) represents the equivalent angular velocity of the load lifting mechanism at the (t+1)th sampling time, θ L (t+1) represents the equivalent angular displacement of the load lifting mechanism at the (t+1)th sampling time. These parameters can be obtained from the nameplate parameters of the main drive motor 1 and the flywheel motor 4, the geometric parameters of the high-speed flywheel rotor 6, the transmission ratio parameters of the three-port differential planetary gearbox 8, and the on-site no-load and loaded identification experiments, and are stored in the parameter table of the cooperative controller 12.

[0044] The active pre-management module is used to obtain the operating schedule and the predicted load torque value within a preset time period issued by the external control system. Simultaneously, it dynamically sets the flywheel reference speed ω based on the operating schedule. ref The target trajectory is defined as follows. The optimization objectives are to minimize the peak torque of the main drive motor 1 and the tracking error of the flywheel speed on the target trajectory. The optimal torque distribution sequence over multiple future control cycles is then solved. Its cost function J can be expressed as: ; Where N is the total number of control cycles, t is the current sampling time, i is the future step size index in the prediction time domain, and T m (t+i) represents the torque of the main drive motor at step t+i within a preset time period, ω f (t+i) represents the actual rotational speed of the flywheel energy storage module at step t+i within a preset future time period; ω ref (t+i) is the reference speed of the flywheel at step t+i, T m,N ω is the rated torque of the main drive motor. f,N The rated speed of the flywheel energy storage module is given by q, and r is a preset weighting coefficient for the main drive motor and the flywheel energy storage module, respectively. The weighting coefficients q and r are used to adjust the relative priority between the main drive motor's torque peak suppression target and the flywheel speed tracking target. Preferably, the value of q ranges from 0.6 to 0.9, and the value of r ranges from 0.1 to 0.4, satisfying q + r = 1. The solution process for the optimal torque distribution sequence satisfies the main drive motor torque constraint, flywheel motor torque constraint, flywheel speed constraint, load-side speed constraint, and torque change rate constraint.

[0045] For example, when the system prioritizes reducing the peak torque of the main drive motor, q=0.8 and r=0.2 can be used; when the system prioritizes flywheel speed tracking accuracy and state of charge recovery, q=0.6 and r=0.4 can be used; in this embodiment, q=0.75 and r=0.25 are preferred. The flywheel reference speed ω ref The speed is dynamically set based on current operating conditions, predicted operating conditions, and the flywheel's permissible speed range. Let the minimum permissible operating speed of the flywheel be ω. f,min The rated operating speed is ω f,N The maximum permissible operating speed is ω f,max ,but: ω f,min ≤ω ref (t+i)≤ω f,max ; Let the reference speed for flywheel pre-acceleration be ω. ref,up The reference speed for flywheel pre-reduction is ω. ref,down : but ; Preferably, ω f,min Take 40% to 60% of the rated speed, ω f,max During the active pre-acceleration energy storage phase, the co-controller 12 sets the flywheel reference speed to ω, which is 100% to 120% of the rated speed. ref= ω f,max During steady-state operation, the flywheel reference speed is set to ω. ref= ω f,N During the active pre-deceleration and rollback phase, the flywheel reference speed is set to ω. ref= ω f,min .

[0046] For example, when solving the above objective function, the cooperative controller 12 simultaneously satisfies the following physical boundary constraints: Main drive motor 1 torque constraint: -T m,max ≤T m (t+i)≤T m,max ; Flywheel motor 4 torque constraint: -T α,max ≤T α (t+i)≤T α,max ; Flywheel speed constraint: ω f,min ≤ω f (t+i)≤ω f,max ; Load-side speed constraint: 0≤ω L (t+i)≤ω L,max ; where ω L (t+i) represents the load-side rotational speed at step t+i within a future preset time period; Load lifting displacement constraint: 0≤θ L (t+i)≤θ L,max ; where θ L (t+i) represents the load-side displacement at step t+i within a preset time period in the future; Flywheel motor 4 current constraint: -i q ,max≤i q (t+i)≤i q,max ; where i q (t+i) represents the q-axis current at step t+i within a preset time period in the future; Flywheel energy storage energy constraints: Among them, E f,min E is the minimum permissible flywheel energy storage capacity. f,max The maximum permissible flywheel energy storage capacity; [ω f (t+i)] 2 Let be the square of the actual rotational speed of the flywheel energy storage module at step t+i within a preset time period in the future.

[0047] (in: , ).

[0048] Meanwhile, to avoid mechanical impact, the torque change rates of the main drive motor 1 and the flywheel motor 4 satisfy the following: |T m (t+i)-T m (t+i-1)∣≤ΔT m,max ; |T α (t+i)-T α (t+i-1)∣≤ΔT α,max ; Among them, T m,max The maximum permissible torque of the main drive motor 1, T α,max T is the maximum permissible torque of flywheel motor 4. α (t+i) represents the planned output torque of flywheel motor 4 at the (t+i)th control time in the future, where T α (t+i-1) represents the planned output torque of flywheel motor 4 at the future control time t+i-1, where T m (t+i-1) represents the torque of the main drive motor at step t+i-1 within a future preset time period, ω L,max θ is the maximum permissible speed on the load side. L,max i is the maximum allowable displacement on the load side. q,max The maximum permissible q-axis current of flywheel motor 4, ΔT m,max and ΔT α,max These represent the maximum allowable torque variation of the main drive motor 1 and the flywheel motor 4 within one control cycle.

[0049] After deriving the optimal sequence through calculation, the cooperative controller follows the rolling time-domain control principle, extracting only the first time-step control command corresponding to the current sampling time t and issuing it for execution, and then refreshing the prediction window at the next time t+1. Based on the above model predictive control algorithm, the discrete gravity energy storage system implements two stages: 1. Active pre-acceleration energy storage stage (before lifting heavy objects): The proactive pre-management module retrieves the predicted load torque value within a preset time period based on the operating schedule issued by the host computer. When a positive step change in the predicted load torque value is detected, it determines that the current time is within a preset time window before the lifting of the heavy object. At this time, the proactive pre-management module extracts only the first time-step torque command (as the motor torque command) from the optimal torque distribution sequence and proactively issues a pre-acceleration command to drive the flywheel motor 4 to operate in motor mode. It utilizes the idle power of the power grid to accelerate the high-speed flywheel rotor 6 in advance to establish overspeed kinetic energy reserves. Although the actual load is still zero, the flywheel motor 4 can utilize the surplus power of the power grid to drive the flywheel rotor 6 from the rated speed to near the preset upper limit speed in advance. When the lifting of the heavy object actually occurs, the flywheel already has a high kinetic energy release margin and can immediately release active power through regenerative braking to assist the main drive motor 1 to start smoothly and eliminate system impact losses.

[0050] 2. Active pre-deceleration and clearing phase (before lowering the heavy object): When a negative step change is detected in the predicted load torque, it is determined that the preset time window before the release action has begun. At this time, the active pre-management module extracts only the first time-step torque command (as a braking torque command) and actively issues a pre-deceleration command, controlling the flywheel motor 4 to operate in generator mode, thus reducing the speed boundary of the flywheel energy storage module in advance. This operation reduces the flywheel speed in advance to reserve a speed margin for absorbing subsequent braking feedback energy. The actual speed of the flywheel motor 4 is forcibly reduced to the minimum safe operating boundary (e.g., 40% of the rated speed). In this way, when there is a large amount of gravitational potential energy feedback, the flywheel energy storage module can absorb the corresponding feedback mechanical energy, avoiding energy backflow into the external microgrid and releasing the heat load and wear risk of the low mechanical brake.

[0051] In one embodiment, this application also provides a cooperative control method for a discrete gravity energy storage system driven by a hybrid flywheel and motor. This method is executed by the aforementioned discrete gravity energy storage system driven by a hybrid flywheel and motor, and includes: Before acquiring the load status of the lifting actuator 9 to extract the total load torque, the cooperative controller 12 first performs load acquisition and verification steps: The collaborative controller 12 acquires the real-time operating parameters (such as three-phase current, speed, etc.) of the main drive motor 1 and the flywheel motor 4 in the flywheel energy storage module 2, and estimates the model observation load torque transmitted to the output end of the planetary carrier 19 online.

[0052] The collaborative controller 12 uses a tension detection unit installed at the lifting end 9 or cable 10 to obtain real-time tension, and calculates the direct measurement load torque by combining the current equivalent winding radius and transmission efficiency.

[0053] The collaborative controller 12 calculates the absolute value of the difference between the model-observed load torque and the directly measured load torque in real time, and determines whether the absolute value is less than or equal to a preset deviation threshold. If so, the sensor data is deemed reliable, and the collaborative controller 12 performs low-frequency parameter verification and correction on the model-observed load torque based on the directly measured load torque, and uses the corrected model-observed load torque as the final total load torque in the next control loop. This effectively avoids the risk of system runaway caused by the failure of a single sensor.

[0054] After obtaining the accurate total load torque, the cooperative controller 12 performs frequency domain decoupling and model prediction scheduling of the torque in parallel: The collaborative controller 12 filters the extracted total load torque based on the load state of the lifting actuator, extracting the low-frequency load torque and the high-frequency load torque. Subsequently, based on the kinematic and dynamic torque balance relationship of the three-port differential planetary gearbox 8, the target torque is mapped to generate the target torque at the ring gear end and the target torque at the sun gear end, thereby dynamically adjusting the torque distribution between the main drive motor 1 and the flywheel energy storage module 2, thus completing the frequency domain decoupling of the torque.

[0055] The cooperative controller 12 acquires the operating timetable and the predicted load torque value within a preset time period issued by the external control system, and dynamically generates the flywheel reference speed as the target trajectory based on the operating timetable. Based on the preset discrete-time state-space model and cost function J, it performs optimization to obtain the optimal torque distribution sequence. Utilizing the rolling time-domain control principle, when determining that the current position is within a preset time window before the lifting or lowering of the load, the cooperative controller 12 extracts only the first time-step torque command from the optimal torque distribution sequence as the actual control output: before the lifting action, it drives the flywheel energy storage module 2 to accelerate in advance to establish overspeed kinetic energy reserves; before the lowering action, it causes the flywheel energy storage module 2 to decelerate in advance to free up kinetic energy absorption capacity.

[0056] In one embodiment, after the above command is issued, the cooperative controller 12 adopts a vector control method based on rotor field orientation at the lower level, and adjusts the quadrature-axis current i q The polarity and amplitude of the command are used to achieve a smooth response under specific operating conditions. The specific steps are as follows: S1. The collaborative controller 12 collects the operating data of the heavy object lifting actuator 9 in real time: when the measured angular velocity of the planetary carrier 19 is zero and a start signal is received, it is determined to be an acceleration start-up condition; when the absolute value of the difference between the measured angular velocity of the planetary carrier 19 and the preset target speed is less than or equal to the preset speed deviation threshold, and the heavy object is predicted to reach the target position based on the equivalent angular displacement on the load side and the operating timetable, it is determined to be a deceleration braking condition; when the fluctuation range of the measured angular velocity of the planetary carrier 19 (such as within 5 consecutive control cycles) is less than ±2% of the rated speed, and the fluctuation range of the directly measured load torque is less than 5% of the rated torque, it is determined to be a steady-state operation condition.

[0057] S2. In the initial stage of entering the accelerated start-up condition, the coordinating controller 12 controls the flywheel energy storage module 2 to operate in a generator braking state. Specifically, based on the compensation power required for load startup, the coordinating controller 12 sends a quadrature-axis current i, opposite to the current rotation direction of the flywheel, to the drive converter of the flywheel motor 4. q The command causes the flywheel motor 4 to output a positive electromagnetic torque (applying braking torque to the high-speed flywheel rotor). Utilizing the differential decoupling characteristics of the three-port differential planetary gearbox 8, the flywheel itself decelerates and descends, releasing its stored rotational kinetic energy. The released mechanical power is transmitted to the sun gear 17 via the output shaft of the flywheel energy storage module 2, and forms a transient compensation torque at the planetary carrier 19 end through the three-port differential planetary gearbox 8. This transient compensation torque handles the main high-frequency transient torque demand during the load startup phase, reducing the response requirements of the main drive motor 1 to peak loads and helping to reduce grid-side current surges and DC bus power fluctuations, thus achieving parallel flywheel deceleration and energy release with load acceleration.

[0058] S3. Under steady-state operating conditions, the main drive motor 1 primarily bears the low-frequency steady-state gravity load torque. Simultaneously, the co-controller 12 executes state-of-charge energy management logic: it monitors the rotational speed of the high-speed flywheel rotor 6 in real time. If the flywheel speed is lower than the preset minimum operating speed, it determines that the flywheel is in a depleted state. At this time, the co-controller 12 controls the main drive motor 1 to output additional power, beyond meeting the load increase requirements, to drive the flywheel motor 4 in electric mode, accelerating the charging of the high-speed flywheel rotor until its speed returns to the rated speed, ensuring that the flywheel always has the ability to adapt to the next start-stop impact.

[0059] S4. When entering the deceleration and braking condition, the coordinating controller 12 controls the flywheel energy storage module 2 to switch to electric acceleration mode. Based on the load-side braking feedback energy and the remaining energy storage capacity of the flywheel, the coordinating controller 12 sends a quadrature-axis current i, in the same direction as the current rotation of the flywheel, to the drive converter of the flywheel motor 4. qThe command causes the flywheel motor 4 to generate electromagnetic torque in the same direction as the rotor's rotation. The flywheel motor 4 absorbs the high-frequency feedback kinetic energy from the output of the planetary carrier 19 and converts it into the rotational kinetic energy of the flywheel. This process not only achieves flexible and smooth deceleration of heavy objects, but also helps to reduce the frequency and wear of mechanical brakes.

[0060] As described above, this application employs a planetary gear system as the power coupling hub, breaking the speed limitation of traditional rigid transmission. This topology allows the flywheel to smoothly decelerate and release energy during the load acceleration phase and withstand transient impact loads. The main drive motor 1 only needs to meet the steady-state power increase requirement, significantly reducing its installed capacity and saving substantial system construction costs. Furthermore, through a frequency-domain hierarchical torque distribution strategy, the high-frequency physical acceleration and deceleration of the flywheel are used to transmit kinetic energy in the mechanical transmission chain, forming an equivalent low-pass filter characteristic. This not only effectively absorbs the mechanical impact when discrete heavy objects are connected, extending the service life of the gearbox and cables, but also shapes the power curve presented to the grid by the system into a smooth trapezoidal wave, completely avoiding voltage flicker. By introducing a model predictive control algorithm, the system upgrades the traditional passive feedback response to active feedforward scheduling through pre-acceleration energy storage before lifting and pre-deceleration clearing before lowering, maximizing the utilization of the flywheel's transient power throughput and energy recovery efficiency.

[0061] It should be noted that during actual operation, the lifting actuator 9 does not limit the direction of the load's movement; it can perform lifting, lowering, hovering, and braking actions. For the lowering process, the coordinating controller 12 can perform corresponding control based on the aforementioned model predictive control algorithm, working condition identification logic, and frequency-domain hierarchical torque distribution strategy: before the lowering action, the coordinating controller 12 can control the high-speed flywheel rotor 6 to pre-decelerate, reserving energy storage capacity for absorbing the feedback energy released during the lowering process; during the lowering start, steady-state descent, and final deceleration processes, the coordinating controller 12 controls the flywheel energy storage module 2 to operate in an electric acceleration state (feedback energy absorption and acceleration state), allowing the flywheel to absorb the high-frequency feedback kinetic energy from the load side through acceleration, while the main drive motor 1 undertakes the low-frequency braking or speed regulation torque, thereby suppressing the instantaneous downward trend of the load, making the lowering process smoother, and realizing brake energy recovery. Therefore, during the lifting process, the flywheel provides transient assistance by decelerating and releasing energy, while during the lowering process, the flywheel absorbs transient buffering by accelerating and absorbing energy, enabling the system to achieve mechanical shock suppression, power fluctuation smoothing, and braking energy recovery in both the lifting and lowering directions.

[0062] For an example, please see Figure 3 This is the flowchart corresponding to the above method. From the flowchart, we can see that the method's process is as follows: ① Data reading and prediction optimization stage Input reading: After the process starts, the system first reads the host computer's running timetable and the load status within the predicted time domain N.

[0063] Optimization Solution: Next, the system solves for the cost function J. This solution process aims to minimize the peak torque of the main drive motor 1 and the flywheel tracking error, thereby generating the optimal torque distribution sequence.

[0064] ② Feedforward preset time window judgment stage Preset lifting window judgment: The system determines whether the current time is within the preset time window before the lifting action of the heavy object.

[0065] If so: Issue an active pre-acceleration command to drive flywheel motor 4 to increase flywheel speed. Then proceed to the stop command judgment stage (i.e., proceed to step ④).

[0066] If not received, the process returns to the initial state and rereads the data.

[0067] If not: Proceed to the next step of the judgment.

[0068] Preset time window judgment: The system determines whether the current time is within the preset time window before the heavy object is lowered.

[0069] If so: Issue an active pre-deceleration command to lower the speed limit of the flywheel energy storage module in advance. Then proceed to step ④.

[0070] If not: Proceed to the real-time data acquisition phase.

[0071] ③ During the real-time operating condition identification and execution phase, the system collects real-time operating data from the execution end (including the measured angular velocity of the planetary carrier, start signal, arrival signal, and directly measured load torque). Based on the current operating condition identification results, it enters three different branch logics. When the speed (measured angular velocity of the planetary carrier) is detected to be zero and a start signal is received, the system determines that it is currently in the "acceleration start condition" and enters branch A. When the fluctuation of the measured angular velocity of the planetary carrier within a preset time period (such as 5 consecutive control cycles) is less than ±2% of the rated speed and the load is stable (for example, the fluctuation amplitude of the directly measured load torque obtained in real time by the tension detection unit is less than 5% of the rated torque within 5 consecutive control cycles), the system determines that it is currently in the "steady-state operation condition" and enters branch B. When the system predicts in advance that the heavy object is about to reach the target position based on the equivalent angular displacement of the load side and the operating timetable in the discrete-time state space model, and the absolute value of the difference between the measured angular velocity of the planetary carrier 19 and the preset target speed is less than or equal to the preset speed deviation threshold, the system determines that it is about to enter the "deceleration braking condition" and enters branch C. The preset speed deviation threshold can be set according to actual engineering needs, for example, to 5% of the target speed; Branch A: Accelerated Startup Condition The cooperative controller 12 converts the first time step command in the optimal torque distribution sequence into corresponding control parameters, controlling the flywheel energy storage module 2 to operate in a generator braking state. The flywheel decelerates, utilizing the differential decoupling characteristics of the planetary gearbox to positively superimpose compensation torque, jointly driving the load acceleration with the main drive motor 1.

[0072] Branch B: Stable operating condition Based on the optimal torque distribution sequence, the cooperative controller 12 controls the main drive motor to bear all the low-frequency steady-state load. Simultaneously, the system monitors the rotational speed of the flywheel energy storage module 2 in real time to determine whether the flywheel speed is lower than the preset minimum operating speed.

[0073] If so: The co-controller 12 extracts the corresponding electric torque command from the optimal sequence, controls the main drive motor to output additional power, and drives the flywheel motor 4 to work in electric mode through the three-port differential planetary gearbox 8 to accelerate the charging of the flywheel rotor until its speed returns to the rated speed. Then it enters the stop command judgment stage (i.e., enters step ④).

[0074] If not: Proceed directly to the stop command judgment stage.

[0075] Branch C: Deceleration and Braking Condition The cooperative controller 12 converts the first time step control command in the optimal torque distribution sequence into a specific action, controlling the flywheel energy storage module 2 to work in electric acceleration mode.

[0076] The flywheel accelerates and absorbs the high-frequency feedback kinetic energy from the output end of the planetary carrier, thereby achieving smooth deceleration of the heavy object.

[0077] ④ Stop command judgment stage After any of the above-mentioned working condition logics has been executed (or no additional action is required), the system will determine whether to issue a system shutdown command: If a stop command is received (Yes): The entire control process ends.

[0078] No shutdown command received (No): The process loop returns to step one, rereads the host computer's running timetable and predicts the load status in the time domain, and starts the next control cycle.

[0079] It is understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0080] Furthermore, although this application uses a coaxial motor coupled flywheel structure as an example, in other embodiments of the present invention, the flywheel energy storage module 2 can also be a high-speed motor directly driving the flywheel or a doubly fed induction motor driving the flywheel; the three-port differential planetary gearbox 8, in addition to the gearbox, can also use non-contact transmission devices such as a hydraulic coupler or a magnetic coupling gear. Any technical solution that utilizes an auxiliary inertial source connected in parallel to the transmission chain to share the transient load falls within the scope of this application.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A discrete gravity energy storage system driven by a hybrid flywheel and motor, characterized in that, include: A three-port differential planetary gearbox, comprising a ring gear, a sun gear, and a planet carrier; A main drive motor, the output shaft of which is connected to the gear ring drive, is used to provide steady-state driving torque for the discrete gravity energy storage system; A flywheel energy storage module, wherein the output shaft of the flywheel energy storage module is connected to the sun gear; A cable, one end of which is connected to a heavy object lifting actuator, and the other end of which is connected to a discrete gravity load; The end of the load lifting actuator away from the cable is connected to the planetary carrier transmission, and is used as a power output end to drive the cable to lift or lower the discrete gravity load. A collaborative controller is electrically connected to the main drive motor and the flywheel energy storage module, respectively. It is used to dynamically adjust the torque distribution according to the load state of the heavy object lifting actuator. It utilizes the differential characteristics of the three-port differential planetary gearbox to realize non-rigid synchronous differential coupling between the flywheel energy storage module and the heavy object lifting actuator. It also enables the flywheel energy storage module to reduce its speed and release rotational kinetic energy under the action of the target torque at the sun gear end during the acceleration period of the discrete gravity load. The collaborative controller is also used to obtain the total load torque at the planetary carrier end, decompose the total load torque into low-frequency load torque and high-frequency load torque, and generate the target torque at the ring gear end and the target torque at the sun gear end based on the torque balance relationship of the three-port differential planetary gearbox, so that the main drive motor undertakes the low-frequency steady-state torque and the flywheel energy storage module undertakes the high-frequency transient torque.

2. The discrete gravity energy storage system driven by a flywheel and a motor according to claim 1, characterized in that: The flywheel energy storage module includes a vacuum housing, and a flywheel rotor, a flywheel motor, a radial permanent magnet bearing, and an axial permanent magnet bearing disposed inside the vacuum housing; The flywheel motor and the flywheel rotor are connected via the same shaft, and the output shaft of the flywheel motor is connected to the sun gear; The radial permanent magnet bearing is used to provide radial support for the flywheel rotor and the shaft, and the axial permanent magnet bearing is used to provide axial support for the flywheel rotor and the shaft. The flywheel energy storage module maintains a continuous transmission connection with the sun gear through the output shaft of the flywheel motor. This continuous transmission connection maintains power transmission during the lifting, acceleration, deceleration, positioning, and lowering of the discrete gravity load, and compensates for or absorbs the high-frequency transient torque at the planetary carrier end through the target torque at the sun gear end.

3. The discrete gravity energy storage system driven by a flywheel and a motor according to claim 2, characterized in that: It also includes the DC bus and the grid-connected bidirectional converter; Both the main drive motor and the flywheel motor are connected to the DC bus through corresponding motor-side converter units; The DC bus is connected to the external power grid through the grid-connected bidirectional converter to form an energy interaction network.

4. The discrete gravity energy storage system with flywheel and motor hybrid drive according to claim 1, characterized in that, The collaborative controller is internally configured with a torque distribution module, which is used for: Obtain the total load torque and virtual inertia coefficient transmitted to the output end of the planetary carrier; The low-frequency load torque is obtained by extracting the steady-state components in the total load torque using a low-pass filter. The high-frequency load torque is obtained by extracting the fast abrupt change component in the total load torque using a high-pass filter. The low-frequency target output torque of the planetary carrier is generated based on the low-frequency load torque, wherein the generation formula is: T * c,L =T load,L ; where T * c,L T is the low frequency target output torque load,L T is the low frequency load torque Obtain the measured angular velocity of the planetary carrier, and generate the high-frequency target output torque of the planetary carrier based on the high-frequency load torque, the virtual inertia coefficient, and the measured angular velocity, wherein the generation formula is: ； Among them, T * c,H For the high-frequency target output torque, T load,H For high-frequency load torque, J vir ω is the virtual inertia coefficient. c The measured angular velocity of the planetary carrier. This is the derivative of the measured angular velocity.

5. The discrete gravity energy storage system with flywheel and motor hybrid drive according to claim 4, characterized in that, The torque distribution module is also used for: The target torque at the gear end of the gear ring is mapped based on the low-frequency load torque and the high-frequency target output torque, wherein the mapping formula is: ； wherein T * r is the target torque of the ring gear end, k is the ratio of the number of teeth of the ring gear to the number of teeth of the sun gear of the planetary gearbox, λ r is the high-frequency sharing coefficient of the main drive motor; The target torque at the sun gear end is mapped based on the low-frequency load torque and the high-frequency target output torque, wherein the mapping formula is: ； Wherein, T * s is the target torque of the sun gear end, λ s is the high-frequency sharing coefficient of the flywheel energy storage module; The cooperative controller is used to control the main drive motor according to the target torque at the gear ring end, and to control the flywheel energy storage module according to the target torque at the sun gear end.

6. The discrete gravity energy storage system with flywheel and motor hybrid drive according to claim 4, characterized in that, The lifting actuator is equipped with a tension detection unit, which is used to acquire the real-time tension, equivalent winding radius and transmission efficiency corresponding to the discrete gravity load in real time. The collaborative controller is also equipped with a load observation and verification module. The load observation and verification module is used to obtain the real-time operating parameters of the main drive motor and the flywheel motor of the flywheel energy storage module, and to estimate the model observation load torque transmitted to the output end of the planetary carrier online based on the real-time operating parameters. It is also used to calculate the directly measured load torque based on the real-time tension, the equivalent winding radius, and the transmission efficiency; It is also used to calculate the difference between the model-observed load torque and the directly measured load torque, and to determine whether the absolute value of the difference is less than or equal to a preset deviation threshold. If the load torque is less than or equal to the preset deviation threshold, the model observed load torque is checked and corrected at low frequency based on the directly measured load torque, and the model observed load torque after low-frequency check and correction is taken as the total load torque. If the deviation exceeds the preset deviation threshold and continues to reach the preset control cycle number, the tension detection unit is determined to be abnormal. The collaborative controller stops using the direct measurement of load torque for verification and switches to using the model observation of load torque based solely on the real-time operating parameters as the basis for output control.

7. The discrete gravity energy storage system with flywheel and motor hybrid drive according to claim 1, characterized in that, The collaborative controller is also equipped with an active pre-management module based on model predictive control: The active pre-management module has a built-in discrete-time state-space model of the discrete gravity energy storage system. The active pre-management module is used to obtain the operating timetable and the predicted load torque value within a preset time period issued by the external control system. It is also used to dynamically generate a flywheel reference speed based on the running schedule, and to use the flywheel reference speed as the target trajectory; It is also used to solve for the optimal torque distribution sequence within multiple control cycles in a future preset time period based on the discrete-time state-space model, with the joint optimization objectives of minimizing the peak torque of the main drive motor and minimizing the tracking error of the actual rotational speed of the flywheel energy storage module on the target trajectory, wherein the cost function J of the discrete-time state-space model is: ； Where N is the total number of control cycles, t is the current sampling time, i is the future step size index in the prediction time domain, and T m (t+i) represents the torque of the main drive motor at step t+i within a preset time period, ω f (t+i) represents the actual rotational speed of the flywheel energy storage module at step t+i within a preset future time period; ω ref (t+i) is the reference speed of the flywheel at step t+i, T m,N ω is the rated torque of the main drive motor. f,N The rated operating speed of the flywheel energy storage module is given by q, and r is a preset weighting coefficient for the main drive motor and the flywheel energy storage module, respectively, and satisfies q+r=1. The process of solving the optimal torque distribution sequence satisfies the main drive motor torque constraint, flywheel motor torque constraint, flywheel speed constraint, load-side speed constraint, and torque change rate constraint.

8. The discrete gravity energy storage system with flywheel and motor hybrid drive according to claim 7, characterized in that, The active pre-management module is also used to retrieve the predicted load torque value within the future preset time period according to the operating schedule; When a positive step is detected in the predicted load torque value, it is determined that the current time is within a preset time window before the lifting action of the heavy object; when a negative step is detected in the predicted load torque value, it is determined that the current time is within a preset time window before the lowering action. If the current time is within a preset time window before the lifting of the heavy object, the active pre-management module only extracts the first time step torque command in the optimal torque distribution sequence as an electric torque command to drive the flywheel energy storage module to accelerate in advance; If it is within the preset time window before the lowering action, the active pre-management module only extracts the first time step torque command in the optimal torque distribution sequence as a braking torque command to make the flywheel energy storage module slow down in advance.

9. A control method for a discrete gravity energy storage system based on a flywheel and motor hybrid drive according to any one of claims 1-8, characterized in that, The method, executed by the cooperative controller, includes: The load status of the lifting actuator is obtained to extract the total load torque, low-frequency load torque, and high-frequency load torque; Based on the torque balance relationship of the three-port differential planetary gearbox, the target torque at the ring gear end and the target torque at the sun gear end are mapped and generated to dynamically adjust the torque distribution between the main drive motor and the flywheel energy storage module. The system obtains the operating timetable and load torque prediction value issued by the external control system, dynamically generates the flywheel reference speed as the target trajectory based on the operating timetable, and performs optimization solution based on the preset discrete time state space model and cost function to obtain the optimal torque distribution sequence. Utilizing the rolling time domain control principle, when determining that the current time window is before the lifting or lowering of the heavy object, only the first time step torque command in the optimal torque distribution sequence is extracted as the actual control output. This drives the flywheel energy storage module to increase speed in advance before lifting, or causes the flywheel energy storage module to decrease speed in advance before lowering.

10. The control method for a discrete gravity energy storage system with hybrid flywheel and motor drive according to claim 9, characterized in that, Before obtaining the load status of the lifting actuator to extract the total load torque, the method further includes: The real-time operating parameters of the main drive motor and the flywheel motor in the flywheel energy storage module are obtained, and the model observation load torque transmitted to the output end of the planetary carrier is estimated online. Obtain real-time tension, equivalent winding radius, and transmission efficiency; calculate the directly measured load torque. Calculate the absolute value of the difference between the model-observed load torque and the directly measured load torque, and determine whether the absolute value is less than or equal to a preset deviation threshold; If so, the model observed load torque is parameter-corrected based on the directly measured load torque, and the corrected model observed load torque is used as the total load torque; If the deviation exceeds the preset deviation threshold and continues to reach the preset control cycle number, the lifting actuator is determined to be abnormal. The collaborative controller stops using the direct measurement of load torque for verification and switches to using the model observation of load torque based solely on the real-time operating parameters as the basis for output control.

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