Engineering machinery electric rotation system with energy recovery function and control method

Abstract

The invention discloses an engineering machinery electric rotation system with an energy recovery function and a control method, and belongs to the field of engineering machinery electronization. The system comprises a rotary motor-generator, a bidirectional inversion unit, a main controller, a power unit and a plurality of sensors, and bidirectional flow of electric energy is realized through a structure of the rotary motor-generator-bidirectional inversion unit; according to the control method, a sensing-decision-execution closed-loop architecture is adopted, and a power generation torque instruction is output through safety judgment of a sensing decision-making layer, multi-algorithm fusion of a power generation torque calculation layer and dynamic optimization of a system collaborative execution layer; the problems of braking kinetic energy waste, unstable braking and safety risks in the prior art are solved, high-stability recovery from mechanical kinetic energy to direct-current electric energy is achieved, operation comfort and equipment endurance are improved, and safe and reliable operation of the system is guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of electrification technology of construction machinery, specifically relating to an electric slewing system and control method for construction machinery with energy recovery function, applicable to construction machinery such as electric excavators that require frequent slewing start-stop operations. Background Technology

[0002] As a core piece of equipment in the engineering construction field, the technological development level of excavators directly affects construction efficiency, energy consumption, and environmental protection. Traditional excavators generally use diesel engines as their power source, driving a hydraulic system to achieve rotation, travel, and working device movements. However, the traditional hydraulic rotation system has inherent technical bottlenecks. On the one hand, the energy conversion path is long, involving multiple conversions of "mechanical energy → hydraulic energy → mechanical energy," resulting in low overall system efficiency, especially with significant energy loss during valve-controlled throttling. On the other hand, under rotation braking conditions, the enormous inertial kinetic energy of the turntable cannot be effectively utilized and can only be converted into heat energy through the relief valve or brake valve in the hydraulic system. This causes a sharp rise in hydraulic oil temperature, resulting in energy waste and requiring larger capacity cooling devices, increasing manufacturing costs and overall machine weight.

[0003] With the electrification of construction machinery becoming an irreversible trend, the "oil-to-electric" conversion solution has initially solved the emission and noise problems of the power source. Electric drive slewing systems, due to their advantages such as short transmission chains, high transmission efficiency, and precise control, are gradually replacing hydraulic slewing systems. However, existing electric slewing technology still has significant shortcomings: technological improvements are mostly focused on operational smoothness and response performance under complex working conditions, while the core control logic remains at the level of "driving" and "consuming" energy, failing to fundamentally solve the problem of inertial energy recovery during slewing braking. Existing electric slewing systems mostly use energy-consuming braking or mechanical friction braking during braking, resulting in a secondary waste of the electric excavator's precious electrical energy and limiting the improvement of its range.

[0004] In summary, the existing electric excavator slewing system is in a crude stage of energy flow management. The huge amount of kinetic energy during frequent start-stop operations cannot be recovered and utilized, which restricts the improvement of energy efficiency of electric construction machinery. At the same time, the braking process is prone to shock, system voltage fluctuations and battery safety risks. There is an urgent need for an innovative electric slewing system and control method to achieve efficient energy recovery and safe and stable operation. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an electric slewing system and control method for engineering machinery with energy recovery function, which solves problems such as energy waste, unstable braking, system voltage surge and battery safety risks during the slewing braking of electric excavators, and achieves a balance of efficient energy recovery, comfortable and smooth operation and extended equipment range.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: an electric slewing system for engineering machinery with energy recovery function, integrated into an electric engineering machinery vehicle, including a slewing motor-generator, a bidirectional inverter unit, a main controller, a power unit, a mechanical brake, a reduction mechanism, a turntable, and multiple sensors;

[0007] The rotary motor-generator has both driving and power generation functions. It is connected to the turntable through the reduction mechanism and is used to drive the turntable to rotate or to convert mechanical energy into electrical energy during braking.

[0008] The mechanical brake is connected in parallel with the rotary motor-generator to provide parking lock and safety redundancy braking.

[0009] The power unit is connected to the bidirectional inverter unit and the controller for controlling the main motor of the hydraulic system via a DC bus, and supplies power to them.

[0010] The bidirectional inverter unit is connected to the controller of the rotary motor to realize bidirectional conversion of electrical energy between drive mode and power generation mode;

[0011] Multiple sensors, including a control handle, a rotation angle sensor, a tilt sensor, and a voltage / current sensor, are used to collect control intention signals, turntable rotation angle signals, turntable tilt signals, and DC bus voltage / current signals, respectively.

[0012] The main controller is connected to the power unit, bidirectional inverter unit, rotary motor controller, main motor controller, and various sensors via a CAN bus. It is used to perform data interaction, generate power generation torque command T_output, and control the start and stop of the energy recovery process.

[0013] Furthermore, the power unit includes a power battery pack, a DC-DC module, and a battery management system. The battery management system is connected to the power battery pack and is used for energy management of the power battery pack. The power battery pack is connected to the DC-DC module, which is connected to a bidirectional inverter unit and a main motor for controlling the hydraulic system via a DC bus. The DC-DC module converts the output voltage of the power battery pack and supplies power to the controllers of the bidirectional inverter unit and the main motor. The battery management system is connected to the main controller via a CAN bus and is used to provide real-time feedback on the state of charge (SOC), temperature, and maximum acceptable charging power P_batt_max of the power battery.

[0014] Furthermore, the connection between the rotary motor controller and the bidirectional inverter unit and the main controller is used to receive torque commands from the main controller and control the speed regulation of the rotary motor-generator in drive mode and the power conversion efficiency in power generation mode.

[0015] Furthermore, the signals collected by the main controller through various sensors include: the opening degree, rate of change, and direction signals of the control handle; the real-time rotation angle, rotation direction, and actual speed signals of the turntable; the X-axis and Y-axis tilt angle signals of the turntable relative to the horizontal plane; the SOC and temperature signals of the power battery; the DC bus voltage signal; and the fault code signals of the inverter and motor.

[0016] An electric slewing control method for engineering machinery with energy recovery function adopts a closed-loop architecture of "perception-decision-execution" and is divided into three layers of control method: the first layer is the perception and decision layer, the second layer is the power generation torque calculation layer, and the third layer is the system collaborative execution layer.

[0017] The perception and decision-making layer performs multi-source signal acquisition, state recognition, and multi-constraint safety decision-making. When the energy recovery safety conditions are met, the energy recovery function is activated.

[0018] Based on the output of the perception and decision layer, the power generation torque calculation layer calculates and synthesizes the preliminary power generation torque command T_final through the basic torque mapping algorithm, the slope adaptive compensation algorithm, and the dynamic safety limiting algorithm.

[0019] The system's collaborative execution layer uses a dynamic hysteresis voltage control algorithm and an intelligent energy flow routing strategy to correct the initial power generation torque command T_final and output the final power generation torque command T_output, thereby controlling the rotary motor-generator to perform energy recovery.

[0020] Furthermore, the multi-source signal acquisition in the perception and decision-making layer specifically involves:

[0021] Control Intent Acquisition: The main controller reads the voltage signal of the control handle by the opening degree (determining the target speed), the rate of change (judging the urgency of the operation), and the direction (left / right rotation);

[0022] Machine status acquisition: The main controller acquires the real-time rotation angle, rotation direction, and actual speed of the motor of the turntable through the rotation angle sensor and the rotation motor speed sensor;

[0023] Environmental attitude acquisition: The main controller obtains the X-axis and Y-axis tilt angles of the turntable relative to the horizontal plane through tilt sensors, which are used for subsequent slope adaptive compensation.

[0024] System health data acquisition: The main controller obtains the state of charge (SOC), temperature, DC bus voltage (V_dc), inverter, and motor component fault codes of the power battery through the battery management system, voltage / current sensors, and the self-diagnostic systems of each controller.

[0025] Furthermore, the state recognition in the perception and decision-making layer is specifically as follows: the main controller determines whether the system is in drive mode, coasting braking mode or reverse braking mode based on the handle signal and the real-time rotation speed N_actual of the rotary motor.

[0026] Specifically, when the handle is open, it is in drive mode and energy recovery is not activated; when the handle is centered and N_actual > N_min (zero speed threshold), it is in coasting braking mode; when the handle is reversed and N_actual > N_min, it is in reverse braking mode.

[0027] Furthermore, the main controller receives all safety-related data from the BMS, sensors, and self-diagnostic system, and performs multi-constraint safety decisions. Its logical judgment conditions include:

[0028] Condition 1: The SOC of the power battery < SOC_max and T_batt_min < T_batt (battery temperature) < T_batt_max; ensuring that the battery has "space" and is at a safe temperature to receive energy;

[0029] Condition 2: No relevant fault codes are found in the inverter, rotary motor-generator, main motor, and key components of the hydraulic system; ensure that the actuators are reliable;

[0030] Condition 3: DC bus voltage V_dc < V_dc_max; ensure that the DC bus has sufficient voltage margin to receive feedback energy without overvoltage;

[0031] When all three conditions are met, the energy recovery function is allowed to be activated, and the command is passed down to the torque calculation layer; if any one condition is not met, the energy recovery function is prohibited, and the system will directly skip the recovery phase and trigger mechanical braking to ensure absolute safety.

[0032] Furthermore, the specific calculation process of the power generation torque calculation layer includes:

[0033] Basic Demand Calculation - Basic Torque Mapping Algorithm: Based on the braking mode determined by the perception decision layer, the corresponding coasting brake mapping table or reverse brake mapping table is queried. Combined with the real-time rotation speed N_actual of the rotary motor, the basic generating torque T_base is output. The coasting brake mapping table has a flat curve and a relatively small T_base to achieve smooth deceleration; the reverse brake mapping table has a steep curve and a larger T_base to achieve rapid deceleration.

[0034] Working condition adaptability calculation - ramp adaptive compensation algorithm: adopts a partitioned PID control algorithm, inputs turntable tilt angle, slewing angle and speed difference ΔN (the difference between target speed N_target and actual speed N_actual), identifies the ramp slewing area based on the change of tilt angle sign and slewing angle, calls the corresponding preset PID parameters (Kp, Ki, Kd) to calculate compensation torque T_comp, and dynamically offsets the influence of gravity;

[0035] Safety and Efficiency Calculation - Dynamic Safety Limit Algorithm: Based on the feedback of P_batt_max from the battery management system and the real-time speed N_actual, calculate the dynamic safety torque limit T_max, T_max=min(T_mech_max, (P_batt_max×η) / N_actual), where T_mech_max is the physical capacity limit of the motor and mechanical transmission components, and η is the system efficiency;

[0036] Torque synthesis and determination: Calculate the total required torque T_req=T_base+T_comp, limit T_req to between 0 and T_max, and obtain the initial generation torque command T_final.

[0037] Furthermore, the specific process of the dynamic hysteresis voltage control algorithm in the system collaborative execution layer is as follows:

[0038] Define the DC bus voltage range as follows: safe zone (V_dc < V_warn, e.g., 740V), warning zone (V_warn ≤ V_dc < V_max, e.g., 740V-750V), and danger zone (V_dc ≥ V_max, e.g., 750V).

[0039] Adjust torque commands for different voltage regions:

[0040] Safe zone: T1=T_final, output all values, no intervention;

[0041] Warning zone: T1 = T_final × K_att, where K_att = 1 - K_pv × (V_dc - V_warn) / (V_max - V_warn), K_pv is the attenuation gain, and the higher the voltage, the smaller K_att;

[0042] Danger zone: T1=0, forcefully disengage energy recovery and activate mechanical braking.

[0043] Furthermore, the specific priority of the energy flow intelligent routing strategy described in the system collaborative execution layer is as follows:

[0044] First priority: When the recovered electrical energy power P_gen ≤ the load power consumption P_load (the load includes the main motor, hydraulic system and other electrical equipment), the recovered electrical energy is given priority to supply the currently working electrical equipment;

[0045] Second priority: When P_gen > P_load and the power battery status allows, the surplus power is stored in the power battery;

[0046] Third priority: When there is an energy surplus but the power battery cannot receive it, set T_max to zero, stop power generation and abandon recycling.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] 1) Efficient energy recovery and extended range: Through the energy feedback architecture of "rotary motor-generator + bidirectional inverter unit", the inertial mechanical energy of the turntable is converted into electrical energy during braking, which is directly supplied to the electrical equipment or charged to the power battery via the DC bus, significantly reducing external charging dependence, extending the single charging operation time, and improving the economy of electric construction machinery.

[0049] 2) Smooth braking under all working conditions, improving operating comfort: Intelligent identification of coasting braking and reverse braking modes, providing differentiated braking torque, and dynamically offsetting the influence of gravity through slope adaptive compensation algorithm, ensuring consistent and smooth braking feel under any slope and turning position, improving operation accuracy and operating comfort.

[0050] 3) Multiple safety protections ensure reliable system operation: By using triple safety constraints of battery status, system health, and bus voltage, dangerous operating conditions are eliminated from the source; combined with a dynamic hysteresis voltage control algorithm, bus voltage fluctuations are smoothly suppressed to prevent overvoltage risks and build a comprehensive safety defense line.

[0051] 4) Intelligent energy allocation to optimize system energy efficiency: The intelligent energy flow routing strategy achieves efficient allocation of recovered energy through priority management, prioritizes local consumption to reduce conversion losses, and balances reasonable storage with safe abandonment of energy, taking into account the lifespan of energy storage equipment and system stability, thereby maximizing the overall system efficiency. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the system of the present invention;

[0053] Figure 2 Flowchart for the perception and decision-making layers;

[0054] Figure 3 Flowchart for multi-objective optimization of power generation torque calculation layer;

[0055] Figure 4 This is a flowchart of the system's collaborative execution layer control process. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of the invention.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0058] like Figure 1 As shown, an electric slewing system for engineering machinery with energy recovery function is integrated into the electric excavator. It adopts an energy feedback architecture consisting of a slewing motor, a generator, and a bidirectional inverter unit. The system mainly includes: a slewing motor-generator, a bidirectional inverter unit, a main controller, a power unit, a mechanical brake, a reduction mechanism, a turntable, and multiple sensors.

[0059] The rotary motor-generator has both driving and power generation functions. It is connected to the turntable through the reduction mechanism and is used to drive the turntable to rotate or to convert mechanical energy into electrical energy during braking.

[0060] The mechanical brake is connected in parallel with the rotary motor-generator to provide parking lock and safety redundancy braking.

[0061] The power unit is connected to the bidirectional inverter unit and the controller for controlling the main motor of the hydraulic system via a DC bus, and supplies power to them.

[0062] The bidirectional inverter unit is connected to the controller of the rotary motor via a CAN bus to realize bidirectional conversion of electrical energy between drive mode and power generation mode.

[0063] Multiple sensors, including a control handle, a rotation angle sensor, a tilt sensor, and a voltage / current sensor, are used to collect control intention signals, turntable rotation angle signals, turntable tilt signals, and DC bus voltage / current signals, respectively.

[0064] The main controller is connected to the power unit, bidirectional inverter unit, rotary motor controller, main motor controller, and various sensors via a CAN bus. It is used to perform data interaction, generate power generation torque command T_output, and control the start and stop of the energy recovery process.

[0065] The power unit includes: a power battery pack, a DC-DC converter module, and a battery management system. The battery management system is connected to the power battery pack for energy management. The power battery pack is connected to the DC-DC converter module, which is connected to the bidirectional inverter unit and the main motor for controlling the hydraulic system via a DC bus. The DC-DC converter module converts the output voltage of the power battery pack and supplies power to the controllers of the bidirectional inverter unit and the main motor. The battery management system is connected to the main controller via a CAN bus for real-time feedback of the power battery's state of charge (SOC), temperature, and maximum acceptable charging power P_batt_max.

[0066] The connection between the rotary motor controller and the bidirectional inverter unit and the main controller is used to receive torque commands from the main controller and control the speed regulation of the rotary motor-generator in drive mode and the power conversion efficiency in power generation mode.

[0067] The signals collected by the main controller through various sensors include: the opening degree, rate of change and direction signal of the control handle, the real-time rotation angle, rotation direction and actual speed signal of the turntable, the X-axis and Y-axis tilt angle signals of the turntable relative to the horizontal plane, the SOC and temperature signals of the power battery, the DC bus voltage signal, and the fault code signals of the inverter and motor.

[0068] A control method for an electric slewing system for engineering machinery with energy recovery function adopts a closed-loop architecture of "perception-decision-execution," with the core being to achieve safe and efficient adaptive energy recovery. The system first identifies the operating intention and system health status in real time through the perception and decision-making layer, enabling the energy recovery function only when multiple safety constraints are met. The power generation torque calculation layer then integrates basic requirements, slope compensation, and dynamic battery power limiting to generate an initial torque command. Finally, the system collaborative execution layer optimizes the command globally through voltage hysteresis control, ensuring that the energy recovery process fully guarantees the overall machine's power performance and grid stability while maximizing energy recovery efficiency, achieving a balance between safety, comfort, and energy saving.

[0069] The generation process of the generated torque T_output is as follows: First, the perception and decision-making layer determines the feasible energy recovery mode based on the handle signal and system status. Next, the generated torque calculation layer synthesizes the preliminary safe torque T_final by integrating the basic torque mapping, slope adaptive PID compensation, and battery dynamic power limiting. Finally, the system collaborative execution layer performs the final evaluation of T_final: hysteresis control is performed based on the DC bus voltage to stabilize the power grid, and energy coordination with the energy storage system is implemented to ultimately output a T_output command that is both highly efficient and absolutely safe.

[0070] A control method for an electric slewing system for engineering machinery with energy recovery function is specifically divided into three layers: the first layer is the perception and decision-making layer, responsible for perceiving the environment, understanding intentions, and making the highest-level safety decisions; the second layer is the torque calculation layer, responsible for converting the higher-level safety decision commands into precise and executable torque commands; the third layer is the system collaborative execution layer, responsible for placing the ideal torque commands output by the calculation layer into the real, dynamic vehicle environment for final adjudication and fine-tuning, ensuring that the energy recovery function coexists harmoniously and operates stably with other systems of the machine; specifically as follows:

[0071] First layer: Perception and decision-making layer

[0072] The perception and decision-making layer is the starting point and prerequisite of the entire control strategy. Its core task is to transform the raw, messy multi-channel sensor signals into a clear, reliable, and executable control command.

[0073] like Figure 2 The diagram illustrates the complete workflow and decision-making logic of the first layer; its detailed process is as follows:

[0074] Step 1: Multi-source signal sensing

[0075] Control intention perception: The main controller reads the voltage signal of the control handle by the opening degree (determining the target speed), the rate of change (judging the speed of operation), and the direction (left / right rotation).

[0076] Machine status awareness: The main controller obtains the real-time rotation angle, rotation direction, and actual speed of the motor of the turntable through the rotation angle sensor and the rotation motor speed sensor.

[0077] Environmental attitude perception: The main controller obtains the X-axis and Y-axis tilt angles of the turntable relative to the horizontal plane through tilt sensors, which are used for subsequent slope adaptive compensation.

[0078] System health awareness: The main controller obtains the state of charge (SOC), temperature, DC bus voltage (V_dc), inverter, motor and other component fault codes of the power battery through the battery management system (BMS), voltage / current sensors and the self-diagnostic systems of each controller.

[0079] Step 2: Status Recognition

[0080] The main controller determines the following three states based on the handle signal and the real-time rotation speed (N_actual) of the rotary motor;

[0081] Drive mode: If the handle opening is valid, the system is in normal electric drive mode and energy recovery is not activated.

[0082] Coasting Brake Mode: If the handle returns to the center (opening is zero) and N_actual > N_min (zero-speed threshold), it is determined that the operator intends to let the turntable coast to a stop. The control objective of this mode is to maximize energy efficiency and comfort;

[0083] Reverse Brake Mode: If the handle is pushed in the opposite direction (opposite to the current rotation direction) and N_actual > N_min, it is determined that the operator intends to stop quickly and reverse. The control objective of this mode is quick response and strong braking;

[0084] Step 3: Multi-constraint Safety Decision

[0085] The main controller receives all safety-related data from the BMS, sensors, and self-diagnostic system, and makes logical judgments:

[0086] Condition 1 (Energy Acceptability): SOC < SOC_max and T_batt_min < T_batt (battery temperature) < T_batt_max; Ensure that the battery has "space" and is at a safe temperature to receive energy;

[0087] Condition 2 (System Health): There are no relevant fault codes for key components such as the inverter and motor; Ensure that the actuator is reliable;

[0088] Condition 3 (Grid Stability): V_dc < V_dc_max; Ensure that the DC bus has enough voltage margin to accept the feedback energy without overvoltage;

[0089] If all three conditions are met, the energy recovery function is executed, and the command is passed down to the torque calculation layer; If any one of the conditions is not met, the energy recovery function is prohibited, and the system will directly skip the recovery stage and trigger mechanical braking to ensure absolute safety.

[0090] The Second Layer: Generation Torque Calculation Layer

[0091] The generation torque calculation layer receives commands from the perception and decision layer, and integrates various sensor information. Through multi-level algorithm fusion, it finally outputs a preliminary generation torque command T_final.

[0092] As Figure 3 shown, it shows the complete calculation process and algorithm interaction of the generation torque calculation layer; Its detailed process is as follows:

[0093] Step 1: Basic Requirement Calculation (Basic Torque Mapping Algorithm)

[0094] The goal of this step is to respond to the operator's intuitive intent and provide a base torque that meets their braking expectations. The system has two pre-stored torque mapping tables that have undergone extensive experimentation and optimization: a coasting braking mapping table and a reverse braking mapping table. The system takes two input parameters: the mode AI and the real-time rotational speed N_actual of the rotary motor. The mode AI is the "coasting braking" or "reverse braking" command from the perception and decision layer. A lookup table method is used to quickly output a base generating torque T_base, which is a torque value that meets the operator's subjective perception requirements.

[0095] Coasting brake mapping table: Its curve is designed to be gentle. At the same speed, the provided T_base is relatively small, aiming to create a linear and smooth deceleration process, maximize energy recovery time, and improve comfort and energy efficiency.

[0096] Reverse braking map: Its curve is steeper. It provides a larger T_base at the same speed, designed to provide a strong drag sensation for rapid deceleration, satisfying the operator's intention to stop suddenly or reverse, prioritizing responsiveness.

[0097] Step 2: Working condition adaptability calculation (ramp adaptive compensation algorithm)

[0098] The goal of this step is to eliminate the impact of slope on braking feel and stability, achieving a consistent operating experience across all terrains. The system employs a zoned PID control algorithm, with three input parameters:

[0099] Turntable tilt angle, real-time tilt angles of the X and Y axes;

[0100] Rotation angle: the angle the turntable rotates from the zero point.

[0101] Speed ​​difference (ΔN) is the difference between the target speed (N_target) and the actual speed (N_actual). During coasting braking, N_target is typically 0.

[0102] The system then uses the change in tilt sign (zero-crossing detection) and rotation angle to accurately determine which preset ramp rotation zone the turntable is currently in (e.g., zone one to zone four). Each zone represents a different direction of gravity component action, and each zone corresponds to a set of pre-calibrated PID parameters (Kp, Ki, Kd). For example, in uphill zones, a stronger integral action may be needed to prevent the turntable from slipping.

[0103] The system then calculates the compensation torque:

[0104] The purpose of T_comp is to dynamically compensate for the effects of gravity. When gravity hinders rotation, T_comp is positive, increasing the braking force slightly; when gravity promotes rotation, T_comp is negative, decreasing the braking force slightly.

[0105] Step 3: Security and Performance Calculation (Dynamic Security Limiting Algorithm)

[0106] The goal of this step is to set a real-time, variable safety ceiling for the generated torque, determined by the weakest link in the system. The system employs a dynamic safety limiting algorithm, taking two parameters as input:

[0107] The maximum acceptable charging power of the battery (P_batt_max) is a key signal provided in real time by the battery management system (BMS), which is dynamically calculated based on the battery's SOC, temperature, and health status.

[0108] Real-time speed (N_actual): The current speed of the rotary motor;

[0109] The system then calculates the dynamic safe torque limit:

[0110]

[0111] Where T_mech_max is the absolute upper limit determined by the physical capabilities of the motor and mechanical transmission components.

[0112] (P_batt_max*η) / N_actual: Converts the battery's power limit into a torque limit at the current speed; where η is the system efficiency.

[0113] The dynamic safety torque limit means that even if the motor is capable of generating greater torque, and even if the operator wants to brake more aggressively, the final generated torque must never exceed the range that the battery can safely accept at this moment.

[0114] Step 4: Torque Synthesis and Final Decision

[0115] This is the final step in the computational layer, integrating all parts and making the final decision. First, the base demand and compensation are added to obtain the total demand torque: T_req = T_base + T_comp; then, the total demand torque is limited within a safe boundary: T_final = clamp(T_req, 0, T_max), where the lower limit of 0 ensures that the generated torque will not be negative (i.e., it will not become the drive torque); finally, the preliminary generated torque command T_final is output. This is a high-quality control command that has passed the three tests of demand matching, operating condition adaptation, and safety compliance.

[0116] The third layer (system collaborative execution layer)

[0117] The system coordination execution layer receives the preliminary power generation torque command T_final from the power generation torque calculation layer. At this time, T_final is an ideal command that has not yet considered the real-time carrying capacity of the vehicle's power grid; the core mission of this layer is to focus on the overall situation of the vehicle, finally coordinate and correct T_final, and output an executable command T_output that is safe, compliant, and does not interfere with the main business.

[0118] As Figure 4 shown, it shows two core cooperative control links of the system coordination execution layer and their internal decision-making logics, and the detailed process is as follows:

[0119] Step 1: Coordination with the DC bus voltage (dynamic hysteresis voltage control algorithm)

[0120] When the rotary motor generates electricity, it can be regarded as a power source that "injects water" into the DC bus. If the injected power is too large or too fast and the consumption and storage cannot keep up, it will cause the bus voltage V_dc to soar sharply (pump-up voltage), endangering the insulation safety of all connected devices. To solve this problem, the present invention adopts the "dynamic hysteresis voltage control algorithm" to manage the voltage in zones and achieve a smooth transition from "stepless fine-tuning" to "emergency cut-off".

[0121] The system inputs two parameters, namely T_final and V_dc (DC bus voltage),

[0122] and defines the voltage regions:

[0123] Safe zone (green): V_dc < V_warn (for example, 740V);

[0124] Warning zone (yellow): V_warn ≤ V_dc < V_max (for example, 740V - 750V);

[0125] Dangerous zone (red): V_dc ≥ V_max (for example, 750V).

[0126] The system adopts a zonal control law to correct the final power generation torque T1 for different voltage regions:

[0127] Safe zone: T1 = T_final, full output, no intervention;

[0128] Warning zone: T1 = T_final * K_att;

[0129] where K_att = 1 - K_pv * (V_dc - V_warn) / (V_max - V_warn), K_pv is the attenuation gain, the higher the voltage, the smaller the attenuation coefficient K_att, and the output torque is smoothly reduced proportionally.

[0130] Dangerous area: When T1 = 0, immediately zero the torque command, forcefully exit the energy recovery, and activate the mechanical brake to ensure safety.

[0131] "Voltage stabilization" is achieved. Compared with the crude switch control, while ensuring safety, it maximizes the effective time of energy recovery and recovers more energy through "meticulous calculation" in the warning area.

[0132] Step 2: Energy coordination with the energy storage system (intelligent energy flow routing strategy)

[0133] The core of this step is to establish a multi-priority energy management mechanism, aiming to solve the "destination" problem of the recovered energy and achieve the optimal overall system energy efficiency and the safe and long life of the energy storage device.

[0134] This system adopts the "intelligent energy flow routing strategy", the core of which is priority management. Although it does not directly correct the torque value, it indirectly realizes global energy management by affecting the "dynamic safety limit" in the power generation torque calculation layer.

[0135] The system inputs 4 parameters, namely the power generation power for energy recovery P_gen, the power consumption of the load P_load, the battery SOC, and the maximum acceptable charging power of the battery P_batt_max; it is divided into three priorities, namely:

[0136] First priority: local consumption (highest immediate efficiency),

[0137] When P_gen ≤ P_load, the recovered electrical energy P_gen is preferentially and directly supplied to the currently working electrical equipment (mainly the main motor); using the natural physical characteristics of the DC bus, the electrical energy will automatically and instantaneously flow to the place with the lowest impedance, that is, the place with the most urgent power demand. There is no conversion loss in this process, and the efficiency is the highest. At this time, T_output = T1.

[0138] Second priority: battery storage (energy storage):

[0139] When P_gen > P_load, generating surplus power P_surplus, and the battery status permits (SOC < SOC_max, normal temperature), then store P_surplus in the battery. At this time, P_batt_max (the maximum acceptable charging power of the battery) is directly used as the key input of the dynamic safety limit algorithm in the power generation torque calculation layer, thus determining the upper limit T_max of the power generation torque from the source and ensuring charging safety.

[0140] Third priority: safe discard (system protection):

[0141] When there is a surplus of energy but the battery cannot receive it (SOC is full, temperature is high, or there is a fault), the system stops generating electricity and abandons recycling by setting T_max to zero, forcing T_output to be zero.

[0142] This system maximizes overall system efficiency and reduces battery load through intelligent routing, and achieves safe energy disposal in extreme situations. These are key factors for the system's long lifespan and high reliability. Its specific advantages are as follows:

[0143] 1) The new hardware topology architecture that combines the integrated design of "rotary motor-generator" with "bidirectional inverter unit" fundamentally changes the energy flow path, enabling the rotary system to operate as a generator during braking, converting inertial energy into electrical energy, and efficiently feeding it back to the DC bus through the bidirectional inverter unit; this not only realizes the recovery of braking kinetic energy to charge the power battery to improve range, but more importantly, it can instantly compensate for the electrical energy required for the main motor to work, significantly improving the overall energy utilization efficiency;

[0144] 2) Based on a multi-constraint safety decision-making hierarchical energy recovery coordination strategy, by setting up multiple "safety gates" including battery status, bus voltage and system health, the energy recovery function is ensured to be activated only within an absolutely safe framework; at the same time, by coordinating with the real-time power of the main drive system, the recovery intensity is dynamically adjusted to prioritize power output, thereby achieving the best balance between overall power and economy under complex operating conditions.

[0145] 3) The adaptive core algorithm system based on the dynamic safety domain binds the upper limit of the generated torque to the real-time acceptance capability of the battery through "dynamic limiting", ensuring the inherent safety of energy recovery; "slope adaptive compensation" eliminates the impact of complex terrain on braking performance, ensuring global optimal performance; and "system coordinated control" realizes the seamless integration of the recovery process with the vehicle's energy network. The three work together to ensure the accurate, safe and efficient execution of the control strategy.

[0146] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electric rotary system for engineering machinery with energy recovery function, integrated into an electric engineering machinery vehicle, characterized in that, include: Rotary motor - generator, bidirectional inverter unit, main controller, power unit, mechanical brake, reduction mechanism, turntable and multiple sensors; The rotary motor-generator has both driving and power generation functions. It is connected to the turntable through the reduction mechanism and is used to drive the turntable to rotate or to convert mechanical energy into electrical energy during braking. The mechanical brake is connected in parallel with the rotary motor-generator to provide parking lock and safety redundancy braking. The power unit is connected to and supplies power to the bidirectional inverter unit and the controller for controlling the main motor of the hydraulic system via a DC bus. The bidirectional inverter unit is connected to the controller of the rotary motor to realize bidirectional conversion of electrical energy between drive mode and power generation mode; Multiple sensors include: a control handle, a rotation angle sensor, a tilt sensor, and a voltage / current sensor, which are used to collect control intention signals, turntable rotation angle signals, turntable tilt signals, and DC bus voltage / current signals, respectively. The main controller is connected to the power unit, the bidirectional inverter unit, the controller of the rotary motor, the controller of the main motor, and various sensors. It is used to perform data interaction, generate the power generation torque command T_output, and control the start and stop of the energy recovery process.

2. The electric rotary system for engineering machinery with energy recovery function according to claim 1, characterized in that: The power unit includes: a power battery pack, a DC-DC converter module, and a battery management system. The battery management system is connected to the power battery pack and is used for energy management of the power battery pack. The power battery pack is connected to the DC-DC converter module, which is connected to a bidirectional inverter unit and a main motor for controlling the hydraulic system via a DC bus. The DC-DC converter module converts the output voltage of the power battery pack and supplies power to the controllers of the bidirectional inverter unit and the main motor. The battery management system is connected to the main controller via a CAN bus and is used to provide real-time feedback on the state of charge (SOC), temperature, and maximum acceptable charging power P_batt_max of the power battery.

3. The electric rotary system for engineering machinery with energy recovery function according to claim 1, characterized in that: The connection between the rotary motor controller and the bidirectional inverter unit and the main controller is used to receive torque commands from the main controller and control the speed regulation of the rotary motor-generator in drive mode and the power conversion efficiency in power generation mode.

4. The electric rotary system for engineering machinery with energy recovery function according to claim 1, characterized in that: The signals collected by the main controller through various sensors include: the opening degree, rate of change and direction signal of the control handle, the real-time rotation angle, rotation direction and actual speed signal of the turntable, the X-axis and Y-axis tilt angle signals of the turntable relative to the horizontal plane, the SOC and temperature signals of the power battery, the DC bus voltage signal, and the fault code signals of the inverter and motor.

5. A control method for an electric rotary system for engineering machinery with energy recovery function as described in any one of claims 1-4, characterized in that, The control method adopts a closed-loop architecture of "perception-decision-execution", which is divided into three layers: the first layer is the perception and decision layer, the second layer is the power generation torque calculation layer, and the third layer is the system collaborative execution layer. The perception and decision-making layer performs multi-source signal acquisition, state recognition, and multi-constraint safety decision-making. When the energy recovery safety conditions are met, the energy recovery function is activated. Based on the output of the perception and decision layer, the power generation torque calculation layer calculates and synthesizes the preliminary power generation torque command T_final through the basic torque mapping algorithm, the slope adaptive compensation algorithm, and the dynamic safety limiting algorithm. The system's collaborative execution layer uses a dynamic hysteresis voltage control algorithm and an intelligent energy flow routing strategy to correct the initial power generation torque command T_final and output the final power generation torque command T_output, thereby controlling the rotary motor-generator to perform energy recovery.

6. The control method for an electric rotary system for engineering machinery with energy recovery function as shown in claim 5, characterized in that, The state recognition in the perception and decision-making layer is as follows: the main controller determines whether the system is in drive mode, coasting braking mode or reverse braking mode based on the handle signal and the real-time rotation speed N_actual of the rotary motor. Specifically, when the handle is open, it is in drive mode and energy recovery is not activated; when the handle is centered and N_actual > N_min (zero speed threshold), it is in coasting braking mode; when the handle is reversed and N_actual > N_min, it is in reverse braking mode.

7. The control method for an electric rotary system for engineering machinery with energy recovery function as shown in claim 5, characterized in that, The logical judgment conditions for multi-constraint security decisions include: Condition 1: The SOC of the power battery < SOC_max and T_batt_min < T_batt (battery temperature) < T_batt_max; ensuring that the battery has "space" and is at a safe temperature to receive energy; Condition 2: No relevant fault codes are found in the inverter, rotary motor-generator, main motor, and key components of the hydraulic system; ensure that the actuators are reliable; Condition 3: DC bus voltage V_dc < V_dc_max; ensure that the DC bus has sufficient voltage margin to receive feedback energy without overvoltage; When all three conditions are met, the energy recovery function is allowed to be activated, and the command is passed down to the torque calculation layer; if any one condition is not met, the energy recovery function is prohibited, and the system will directly skip the recovery phase and trigger mechanical braking to ensure absolute safety.

8. The control method for an electric rotary system for engineering machinery with energy recovery function as shown in claim 5, characterized in that, The specific calculation process of the power generation torque calculation layer includes: Basic Demand Calculation - Basic Torque Mapping Algorithm: Based on the braking mode determined by the perception decision layer, query the corresponding coasting brake mapping table or reverse brake mapping table, and combine it with the real-time speed N_actual of the rotary motor to output the basic generating torque T_base; Working condition adaptability calculation - ramp adaptive compensation algorithm: adopting a partitioned PID control algorithm, inputting the turntable tilt angle, slewing angle and speed difference ΔN, and calculating the compensation torque T_comp, where the speed difference ΔN is the difference between the target speed N_target and the actual speed N_actual; Safety and Efficiency Calculation - Dynamic Safety Limit Algorithm: Based on the feedback of P_batt_max from the battery management system and the real-time speed N_actual, calculate the dynamic safety torque limit T_max, T_max=min(T_mech_max, (P_batt_max×η) / N_actual), where T_mech_max is the physical capacity limit of the motor and mechanical transmission components, and η is the system efficiency; Torque synthesis and determination: Calculate the total required torque T_req=T_base+T_comp, limit T_req to between 0 and T_max, and obtain the initial generation torque command T_final.

9. The control method for an electric rotary system for engineering machinery with energy recovery function as shown in claim 5, characterized in that, The specific process of the dynamic hysteresis voltage control algorithm in the system collaborative execution layer is as follows: Define the DC bus voltage regions: safe zone (V_dc < V_warn), warning zone (V_warn ≤ V_dc < V_max), and danger zone (V_dc ≥ V_max). Adjust the torque command for different voltage regions: safe zone: T1 = T_final, full output; warning zone: T1 = T_final × K_att, where K_att = 1 - K_pv × (V_dc - V_warn) / (V_max - V_warn), and K_pv is the attenuation gain; danger zone: T1 = 0, forcibly exit energy recovery and activate mechanical braking.

10. The control method for an electric rotary system for engineering machinery with energy recovery function as shown in claim 5, characterized in that, The specific priorities of the energy flow intelligent routing strategy described in the system collaborative execution layer are as follows: First priority: When the recovered electrical energy power P_gen ≤ the load power consumption P_load (the load includes the main motor, hydraulic system and other electrical equipment), the recovered electrical energy is given priority to supply the currently working electrical equipment; Second priority: When P_gen > P_load and the power battery status allows, the surplus power is stored in the power battery; Third priority: When there is an energy surplus but the power battery cannot receive it, set T_max to zero, stop power generation and abandon recycling.

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