A composite braking and energy recovery cooperative control system and method for an electric traction motor

Abstract

This application discloses a combined braking and energy recovery control system and method for an electric traction machine, relating to the field of power construction equipment technology. The system includes a permanent magnet synchronous motor drive unit, a transmission mechanism, a power-loss mechanical braking device, an energy storage device, and a control unit. During deceleration or downhill cable laying, the permanent magnet synchronous motor enters a power generation mode, converting kinetic energy into electrical energy and storing it in the energy storage device. During emergency braking, the control unit issues a zero-speed lock, and the controller uses closed-loop control to smoothly bring the traction drum to a complete stop. After confirming the traction drum has stopped, the power-loss mechanical braking device mechanically locks itself. After successful mechanical locking, the zero-speed lock of the permanent magnet synchronous motor is released. When releasing the brake, the control unit activates the zero-speed lock and then releases the power-loss mechanical braking device, ensuring unlocking without displacement. This application improves braking safety, energy utilization efficiency, and system reliability through a dual mechanism of "zero-speed locking + power-loss braking."

Description

Technical Field

[0001] This application relates to the field of power construction equipment technology, and in particular to a composite braking and energy recovery coordinated control system and method for an electric traction machine used in tension stringing construction of high-voltage transmission lines. Background Technology

[0002] At present, the traction machines used in the tension stringing construction of high-voltage transmission lines are still mainly diesel-hydraulic driven. The hydraulic system converts kinetic energy into heat energy through the overflow valve, which not only wastes energy, but also easily leads to excessive hydraulic oil temperature and aging of seals, affecting the reliability and service life of the equipment. Although some companies have tried to use variable frequency motor drive to replace the hydraulic system or use motor drive hydraulic pump, the existing solutions still face two major technical bottlenecks: (1) Insufficient braking safety: relying solely on motor torque or hydraulic overflow to maintain the stop state, once the main power supply or control system fails, the traction drum will run out of control; (2) Short brake life: if mechanical braking (i.e. dynamic locking) is applied directly without achieving a zero-speed smooth stop, the brake will be subjected to impact load, causing severe wear of the friction pads, requiring frequent maintenance.

[0003] Related technologies propose a composite braking torque distribution method for electric vehicles, which focuses on dynamically coordinating the torque distribution between the motor and hydraulic brakes according to the driver's needs during vehicle operation. This falls under the category of dynamic control strategies but does not address static safety assurance after equipment shutdown. In addition, related technologies propose a centralized power management device for electric tensioning equipment, which focuses on achieving unified energy management through a common power battery. However, this solution focuses on the "recovery and sharing" of energy and does not delve into the safety coordination mechanism of the traction machine itself during braking.

[0004] Therefore, there is an urgent need to develop a collaborative control system that integrates zero-speed locking of permanent magnet synchronous motor, power-loss mechanical braking, and braking energy recovery. This system can efficiently recover downhill kinetic energy, ensure static braking safety through the dual mechanisms of "electric zero-speed locking and mechanical power-loss locking," and significantly extend the service life of the brakes. This is of great practical significance for comprehensively improving the overall performance of electric traction machines. Summary of the Invention

[0005] The purpose of this application is to provide a combined braking and energy recovery control system and method for electric traction machines, in order to solve the problems of insufficient static braking safety, serious energy waste, and short life of mechanical brakes in the prior art, and to improve the safety, energy efficiency and reliability of electric traction machines in tension line construction.

[0006] To achieve the above objectives, this application provides the following solution: This application provides a combined braking and energy recovery control system for an electric traction machine. The combined braking and energy recovery control system for the electric traction machine includes: a permanent magnet synchronous motor drive unit, a transmission mechanism, a power-off mechanical braking device, an energy storage device, and a control unit; the permanent magnet synchronous motor drive unit includes a permanent magnet synchronous motor and a permanent magnet synchronous motor controller. The permanent magnet synchronous motor drives the traction drum through a transmission mechanism; the power-off mechanical braking device is installed between the output end of the permanent magnet synchronous motor and the transmission mechanism; the DC bus of the permanent magnet synchronous motor controller is electrically connected to the energy storage device, the AC output end of the permanent magnet synchronous motor controller is connected to the permanent magnet synchronous motor, and the control interface of the permanent magnet synchronous motor controller is communicatively connected to the control unit; the power-off mechanical braking device is connected to the control unit. The permanent magnet synchronous motor drive unit is used to convert kinetic energy into electrical energy and store it in the energy storage device when the electric traction machine is in a deceleration or downhill cable laying condition and the permanent magnet synchronous motor enters the power generation mode. The control unit is used for: When an emergency braking command is received or a main power failure is detected, a zero-speed lock command is sent to the permanent magnet synchronous motor controller, which then uses closed-loop control to decelerate the traction drum to a standstill. After confirming that the traction drum has come to a complete stop, the power-off mechanical brake device is controlled to perform mechanical locking. After confirming that the power-off mechanical brake device has successfully locked, the zero-speed lock of the permanent magnet synchronous motor drive unit is released, so that the permanent magnet synchronous motor is de-energized. When it is necessary to release the power-deprived mechanical brake device, a zero-speed lock command is first sent to the permanent magnet synchronous motor controller, and then the power-deprived mechanical brake device is released.

[0007] In one embodiment, the zero-speed locking function is achieved through closed-loop control of the permanent magnet synchronous motor controller. Based on the actual position or speed information fed back by the rotary transformer or encoder, a corrective torque is generated to keep the traction drum stationary.

[0008] In one embodiment, the power-off mechanical braking device is an electromagnetic brake or a hydraulic brake, used to automatically engage the brake when power is lost or the control unit is not powered, thereby achieving static locking of the traction drum.

[0009] In one embodiment, the transmission mechanism is a speed reducer, used to convert the high speed and low torque of the permanent magnet synchronous motor into the low speed and high torque required for the traction drum.

[0010] In one embodiment, when the state of charge of the energy storage device is greater than a preset first threshold or the ambient temperature is lower than a preset second threshold, the control unit preferentially uses a power-off mechanical braking device for braking.

[0011] Secondly, this application provides a method for coordinated control of compound braking and energy recovery in an electric traction machine. This method is executed by the same control system for the same electric traction machine, and includes the following components: When the electric traction machine is decelerating or going downhill for cable laying, the permanent magnet synchronous motor enters the power generation mode, converting kinetic energy into electrical energy and storing it in the energy storage device. When an emergency braking command is received or a main power failure is detected, the control unit sends a zero-speed lock command to the permanent magnet synchronous motor controller. The permanent magnet synchronous motor controller then uses closed-loop control to decelerate the traction drum to a standstill. After the control unit confirms that the traction drum has come to a complete stop, it controls the power-off mechanical brake device to implement mechanical locking. After confirming that the power-off mechanical brake device has successfully locked, it releases the zero-speed lock of the permanent magnet synchronous motor drive unit, causing the permanent magnet synchronous motor to lose power. When it is necessary to release the power-loss mechanical brake, the control unit first sends a zero-speed lock command to the permanent magnet synchronous motor controller, and then controls the power-loss mechanical brake to release.

[0012] According to the specific embodiments provided in this application, this application has the following technical effects: This application discloses a composite braking and energy recovery coordinated control system and method for an electric traction machine. First, by controlling the permanent magnet synchronous motor to enter power generation mode, kinetic energy is converted into electrical energy for storage, achieving energy recovery and changing the traditional friction braking mode that dissipates kinetic and thermal energy, thus achieving energy saving. Second, in case of emergency or power failure, the permanent magnet synchronous motor is controlled to activate a zero-speed locking function, maintaining zero-speed locking. After stopping, the braking device is controlled to mechanically lock. After confirming successful mechanical locking, the zero-speed locking function of the permanent magnet synchronous motor is released. A timing logic of "electric braking first deceleration and locking - mechanical braking static backup - motor then exiting" is designed, constructing a seamless safety chain from dynamic to static, ensuring the safety of the equipment throughout the entire process from movement to complete stillness and reliable locking. This design allows the permanent magnet synchronous motor to undertake the main dynamic braking and deceleration tasks. Zero-speed locking ensures that the mechanical braking is activated only when the traction drum is absolutely stationary and has no residual kinetic energy, fundamentally avoiding dynamic impact loads on the braking device. The mechanical braking acts as a final safety lock only after the equipment has come to a complete stop, reducing friction and wear on the mechanical brake and thermal load, preventing performance degradation due to overheating, thus protecting the brake, extending its lifespan, and improving the reliability of the entire system. Finally, during release, the permanent magnet synchronous motor is first controlled to activate the zero-speed locking function, and then the braking device is controlled to release. This sequence ensures that the motor's braking torque is established and immediately takes over at the instant the mechanical braking force is released, preventing any possible torque interruption and slippage risk, achieving a safe braking release process. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 A schematic diagram of the module structure of a combined braking and energy recovery coordinated control system for an electric traction machine provided in an embodiment of this application; Figure 2 This is a schematic diagram of an emergency braking process provided in an embodiment of this application; Figure 3 A schematic diagram of the combined braking and energy recovery control system for an electric traction machine provided in an embodiment of this application; Detailed Implementation

[0015] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0016] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] In one exemplary embodiment, such as Figure 1 As shown, a combined braking and energy recovery control system for an electric traction machine is provided. The combined braking and energy recovery control system for the electric traction machine includes: a permanent magnet synchronous motor drive unit, a transmission mechanism, a power-off mechanical braking device, an energy storage device, and a control unit; the permanent magnet synchronous motor drive unit includes a permanent magnet synchronous motor and a permanent magnet synchronous motor controller. The permanent magnet synchronous motor drives the traction drum through a transmission mechanism; the power-off mechanical braking device is installed between the output end of the permanent magnet synchronous motor and the transmission mechanism; the DC bus of the permanent magnet synchronous motor controller is electrically connected to the energy storage device, the AC output end of the permanent magnet synchronous motor controller is connected to the permanent magnet synchronous motor, and the control interface of the permanent magnet synchronous motor controller is communicatively connected to the control unit; the power-off mechanical braking device is connected to the control unit. The permanent magnet synchronous motor drive unit is used to convert kinetic energy into electrical energy and store it in the energy storage device when the electric traction machine is in a deceleration or downhill cable laying condition and the permanent magnet synchronous motor enters the power generation mode. The control unit is used for: When an emergency braking command is received or a main power failure is detected, a zero-speed lock command is sent to the permanent magnet synchronous motor controller, which then uses closed-loop control to decelerate the traction drum to a standstill. After confirming that the traction drum has come to a complete stop, the power-off mechanical brake device is controlled to perform mechanical locking. After confirming that the power-off mechanical brake device has successfully locked, the zero-speed lock of the permanent magnet synchronous motor drive unit is released, so that the permanent magnet synchronous motor is de-energized. When it is necessary to release the power-deprived mechanical brake device, a zero-speed lock command is first sent to the permanent magnet synchronous motor controller, and then the power-deprived mechanical brake device is released.

[0018] As an optional implementation, the zero-speed locking function is achieved through closed-loop control of the permanent magnet synchronous motor controller. Based on the actual position or speed information fed back by the rotary transformer or encoder, a corrective torque is generated to keep the traction drum stationary.

[0019] Specifically, the permanent magnet synchronous motor and its controller serve as a regenerative braking unit and a zero-speed locking unit, achieving zero-speed locking through the permanent magnet synchronous motor and its controller. The zero-speed locking function refers to the control unit forming a precise position feedback through the controller of the permanent magnet synchronous motor and the rotary transformer installed on the motor shaft, forming a position closed-loop control unit. When the system detects that external disturbances cause a slight displacement of the drum, the controller can immediately adjust the drive current of the motor to generate a reverse corrective torque, thereby firmly locking the traction drum in the target position.

[0020] As an optional implementation, the power-off mechanical braking device is an electromagnetic brake or a hydraulic brake, used to automatically engage the brake when power is lost or the control unit is not powered, thereby achieving static locking of the traction drum.

[0021] Specifically, hydraulic or electromagnetic brakes are used to provide mechanical locking in the event of a power outage or emergency. When the control unit needs to release the hydraulic or electromagnetic brake, it first controls the permanent magnet synchronous motor to activate the zero-speed locking function, and then sends a release command to the hydraulic or electromagnetic brake. After the hydraulic or electromagnetic brake is released, the zero-speed locking function of the permanent magnet synchronous motor can immediately establish torque to replace the hydraulic or electromagnetic brake and firmly lock the traction drum.

[0022] As an optional implementation, the transmission mechanism is a speed reducer, used to convert the high speed and low torque of the permanent magnet synchronous motor into the low speed and high torque required for the traction drum.

[0023] As an optional implementation, when the state of charge of the energy storage device is greater than a preset first threshold or the ambient temperature is lower than a preset second threshold, the control unit preferentially uses a power-off mechanical braking device for braking.

[0024] Specifically, the energy storage device includes a power battery pack and its management system. The power battery pack is a lithium-ion power battery pack.

[0025] Specifically, the emergency braking procedure is as follows: Figure 2 As shown: S1: When the control unit receives an emergency braking command, it immediately activates the zero-speed locking function, using the zero-speed locking characteristics of the permanent magnet synchronous motor to firmly lock the traction drum.

[0026] S2, waiting for the zero-speed lock function to complete.

[0027] S3 activates the hydraulic or electromagnetic brake for mechanical locking.

[0028] S4, wait for the mechanical locking to complete.

[0029] S5, unlock the zero-speed lock function.

[0030] If the system experiences a power outage, the hydraulic or electromagnetic brake will automatically engage as a last line of defense for safety.

[0031] When the brake needs to be released, the control unit first activates the zero-speed locking function of the motor and its controller, and then sends a release command to the hydraulic or electromagnetic brake. As the brake is released, the static torque generated by the permanent magnet synchronous motor immediately acts on the transmission chain, firmly locking the traction drum, thus achieving smooth and safe unlocking.

[0032] Based on the same inventive concept, this application also provides a method for the coordinated control of combined braking and energy recovery of an electric traction machine, based on the aforementioned coordinated control system for combined braking and energy recovery of the electric traction machine. The solution provided by this method is similar to the implementation described in the above system. Therefore, the specific limitations in one or more embodiments of the coordinated control method for combined braking and energy recovery of an electric traction machine provided below can be found in the limitations of the coordinated control system for combined braking and energy recovery of the electric traction machine described above, and will not be repeated here.

[0033] In one exemplary embodiment, such as Figure 3 As shown, a combined braking and energy recovery coordinated control method for an electric traction machine is provided, including: Step 1: When the electric traction machine is decelerating or going downhill for cable laying, the permanent magnet synchronous motor enters the power generation mode, converting kinetic energy into electrical energy and storing it in the energy storage device. Step 1 is the energy recovery stage.

[0034] Step 2: When an emergency braking command is received or a main power failure is detected, the control unit sends a zero-speed lock command to the permanent magnet synchronous motor controller. The permanent magnet synchronous motor controller then uses closed-loop control to decelerate the traction drum to a stop.

[0035] Specifically, step 2 is the emergency response and zero-speed locking phase. When the system receives an emergency braking command or detects a loss of main power, it immediately triggers the permanent magnet synchronous motor (PMSM) to activate the zero-speed locking function. The control unit sends a zero-speed locking command to the PMSM controller, causing the motor to enter a zero-speed locking state. The zero-speed locking characteristic of the PMSM is used to firmly lock the traction drum. During this process, the PMSM generates a controllable braking torque, causing the traction drum to decelerate smoothly until it comes to a complete stop. After stopping, the system uses a rotary transformer sensor to achieve high-precision closed-loop position control, ensuring the PMSM continuously outputs locking torque to maintain the traction drum in a reliable zero-speed locked state, thus ensuring equipment safety.

[0036] Step 3: After the control unit confirms that the traction drum has completely stopped, it controls the power-off mechanical braking device to implement mechanical locking. After confirming that the power-off mechanical braking device has successfully locked, it releases the zero-speed lock of the permanent magnet synchronous motor drive unit, causing the permanent magnet synchronous motor to lose power.

[0037] Specifically, step 3 is the coordinated braking-release of the electrical brake stage. After confirming that the traction drum has come to a complete stop, the control unit activates the hydraulic brake or electromagnetic brake to perform a holding brake action, thereby mechanically locking the traction drum.

[0038] After confirming that the hydraulic or electromagnetic brake has completed mechanical locking, the control unit releases the zero-speed lock function of the permanent magnet synchronous motor, causing it to stop outputting torque and enter standby mode.

[0039] Step 4: When it is necessary to release the power-deprived mechanical brake device, the control unit first sends a zero-speed lock command to the permanent magnet synchronous motor controller, and then controls the power-deprived mechanical brake device to release.

[0040] Specifically, step 4 is the unlocking preparation and mechanical brake release stage. When it is necessary to release the hydraulic or electromagnetic brake, the control unit first activates the zero-speed locking function of the permanent magnet synchronous motor to achieve closed-loop locking of the motor position, and then sends a release command to the hydraulic or electromagnetic brake.

[0041] Then the mechanical brake is released, and under the zero-speed locking function of the motor, the permanent magnet synchronous motor generates torque to immediately replace the torque of the mechanical brake and firmly lock the traction drum, completing the unlocking process.

[0042] Beneficial effects: 1) High-efficiency energy recovery: During conventional braking or downhill cable laying, the permanent magnet synchronous motor and its controller are used first for regenerative braking, converting kinetic energy into electrical energy and storing it in the power battery pack, maximizing the recovery of braking energy and significantly improving energy utilization.

[0043] 2) High safety: A dual safety barrier of "zero-speed locking + power failure brake" is constructed, ensuring absolute safety even if one system fails. Upon receiving an emergency braking command, the "zero-speed locking" function of the permanent magnet synchronous motor is first used to smoothly and quickly decelerate the traction drum to a complete stop, eliminating dynamic torque; then, the hydraulic or electromagnetic brake is activated for mechanical locking, forming a double insurance.

[0044] 3) Long service life: The "zero speed lock" function actively completes the shutdown process, ensuring that the hydraulic or electromagnetic brake is put into operation at zero speed, thereby avoiding the high dynamic torque and impact, greatly reducing wear and extending service life.

[0045] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0046] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the system, method, and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A composite braking and energy recovery cooperative control system for an electric traction machine, characterized in that, The combined braking and energy recovery control system of the electric traction machine includes: a permanent magnet synchronous motor drive unit, a transmission mechanism, a power-loss mechanical braking device, an energy storage device, and a control unit; the permanent magnet synchronous motor drive unit includes a permanent magnet synchronous motor and a permanent magnet synchronous motor controller. The permanent magnet synchronous motor drives the traction drum through a transmission mechanism; the power-off mechanical braking device is installed between the output end of the permanent magnet synchronous motor and the transmission mechanism; the DC bus of the permanent magnet synchronous motor controller is electrically connected to the energy storage device, the AC output end of the permanent magnet synchronous motor controller is connected to the permanent magnet synchronous motor, and the control interface of the permanent magnet synchronous motor controller is communicatively connected to the control unit; the power-off mechanical braking device is connected to the control unit. The permanent magnet synchronous motor drive unit is used to convert kinetic energy into electrical energy and store it in the energy storage device when the electric traction machine is in a deceleration or downhill cable laying condition and the permanent magnet synchronous motor enters the power generation mode. The control unit is used for: When an emergency braking command is received or a main power failure is detected, a zero-speed lock command is sent to the permanent magnet synchronous motor controller, which then uses closed-loop control to decelerate the traction drum to a standstill. After confirming that the traction drum has come to a complete stop, the power-off mechanical brake device is controlled to perform mechanical locking. After confirming that the power-off mechanical brake device has successfully locked, the zero-speed lock of the permanent magnet synchronous motor drive unit is released, so that the permanent magnet synchronous motor is de-energized. When it is necessary to release the power-deprived mechanical brake device, a zero-speed lock command is first sent to the permanent magnet synchronous motor controller, and then the power-deprived mechanical brake device is released.

2. The hybrid braking and energy recovery cooperative control system for an electric traction motor of claim 1, wherein, The zero-speed locking function is achieved through closed-loop control of the permanent magnet synchronous motor controller. Based on the actual position or speed information fed back by the rotary transformer or encoder, a corrective torque is generated to keep the traction drum stationary.

3. The combined braking and energy recovery coordinated control system for the electric traction machine according to claim 1, characterized in that, The power-off mechanical braking device is an electromagnetic brake or a hydraulic brake, used to automatically engage the brake when power is lost or the control unit is not powered, thereby achieving static locking of the traction drum.

4. The combined braking and energy recovery coordinated control system for the electric traction machine according to claim 1, characterized in that, The transmission mechanism is a speed reducer, used to convert the high speed and low torque of the permanent magnet synchronous motor into the low speed and high torque required for the traction drum.

5. The combined braking and energy recovery coordinated control system for the electric traction machine according to claim 1, characterized in that, When the state of charge of the energy storage device is greater than a preset first threshold or the ambient temperature is lower than a preset second threshold, the control unit will preferentially use the power-off mechanical braking device for braking.

6. A method for coordinated control of compound braking and energy recovery in an electric traction machine, characterized in that, The combined braking and energy recovery coordinated control method of the electric traction machine is executed by the combined braking and energy recovery coordinated control system of the electric traction machine according to any one of claims 1-5, and the combined braking and energy recovery coordinated control method of the electric traction machine includes: When the electric traction machine is decelerating or going downhill for cable laying, the permanent magnet synchronous motor enters the power generation mode, converting kinetic energy into electrical energy and storing it in the energy storage device. When an emergency braking command is received or a main power failure is detected, the control unit sends a zero-speed lock command to the permanent magnet synchronous motor controller. The permanent magnet synchronous motor controller then uses closed-loop control to decelerate the traction drum to a standstill. After the control unit confirms that the traction drum has come to a complete stop, it controls the power-off mechanical brake device to implement mechanical locking. After confirming that the power-off mechanical brake device has successfully locked, it releases the zero-speed lock of the permanent magnet synchronous motor drive unit, causing the permanent magnet synchronous motor to lose power. When it is necessary to release the power-loss mechanical brake, the control unit first sends a zero-speed lock command to the permanent magnet synchronous motor controller, and then controls the power-loss mechanical brake to release.

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