A wind turbine blade speed control device and speed control method

Abstract

This invention discloses a wind turbine blade speed control device and method. The wind turbine blade speed control device includes a speed measurement unit and a main shaft brake disc, the main shaft brake disc being fixedly installed on the blade's main shaft. It also includes a first brake actuation component and a second brake actuation component. The first brake actuation component includes brake pads and brake calipers to achieve braking under a first operating condition. The second brake actuation component includes multiple permanent magnets, multiple coils, a power supply, and a controller to achieve blade speed regulation under a second operating condition. The speed control method involves real-time acquisition of blade speed signals and permanent magnet phase signals by the speed measurement unit, and transmission of these signals to the controller. The controller identifies the current operating condition and executes corresponding control logic. This wind turbine blade speed control device and method effectively avoid dry friction during blade deceleration and braking, ensuring reliable braking of the wind turbine blades.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, specifically to a wind turbine blade speed control device and speed control method. Background Technology

[0002] Wind turbine generators need to maintain stable speed and safe operation over long periods under complex wind conditions. Blade overspeed, load impact, and brake failure are important factors that can lead to unit failures and safety accidents. Currently, the mainstream braking methods in the industry are divided into two main categories: pure mechanical friction braking and pure electromagnetic braking. Both types of solutions have obvious shortcomings and are difficult to adapt to the full operating conditions of the unit.

[0003] Pure mechanical friction braking relies on the frictional torque generated by the contact between the brake pads and the main shaft brake disc to complete the braking operation. It has strong static locking capability, meeting the requirements of long-term static operation conditions such as unit inspections. However, in high-frequency operating scenarios such as daily blade speed control and overspeed suppression, continuous contact between the friction pairs can lead to severe dry friction problems. This not only accelerates the wear of braking components and increases equipment maintenance costs, but the large amount of heat generated during friction can also easily cause thermal deformation of the main shaft brake disc and a decrease in braking performance. Furthermore, mechanical braking can only achieve on / off operation and cannot linearly adjust the braking torque. The deceleration process is prone to rigid impacts, and the additional load will act on the main shaft, gearbox, and other transmission structures, exacerbating component fatigue damage and affecting the overall service life of the machine.

[0004] Pure electromagnetic braking relies on the interaction of magnetic fields to generate damping torque, which is a non-contact speed regulation method and does not have the problem of mechanical wear. However, its braking torque is highly dependent on the rotational speed, and the braking torque decreases sharply in the low-speed range, making it impossible to provide stable and sufficient braking force at low speeds. This makes it difficult to achieve reliable stopping and zero-speed holding, and it is prone to the phenomenon of "low-speed slippage and unstable stopping". Furthermore, this type of structure cannot provide stable static locking force. Once the power is cut off, the damping effect disappears immediately, and it cannot achieve reliable locking of the blades for a long time. Therefore, it cannot be used in equipment maintenance, fixed parking and other working conditions.

[0005] In summary, the existing single braking structure cannot simultaneously meet the multiple requirements of low-wear speed regulation, low-speed stable braking and reliable mechanical locking, becoming a technical bottleneck restricting the operational stability and overall performance improvement of wind turbine units. Summary of the Invention

[0006] To overcome the above-mentioned shortcomings in the prior art, the present invention provides a wind turbine blade speed control device and speed control method that can avoid dry grinding during wind turbine blade deceleration and braking, and ensure reliable braking of wind turbine blades.

[0007] The technical solution of the present invention is, in one aspect, as follows: A wind turbine blade speed control device includes a speed measurement unit and a main shaft brake disc, wherein the speed measurement unit is used to measure the blade speed and phase. The main shaft brake disc is fixedly installed on the blade main shaft, and also includes a first brake actuation component and a second brake actuation component; The first braking actuation component includes a brake pad and a brake caliper. The brake pad is mounted on the brake caliper. The main shaft brake disc has a friction part on its disc surface that mates with the brake pad. The brake caliper drives the brake pad to achieve braking to a stop under the first working condition. The second braking actuator includes multiple permanent magnets, multiple coils, a power supply, and a controller. The multiple permanent magnets are evenly distributed circumferentially along the outer edge of the main shaft brake disc. The multiple coils are fixedly connected to the frame via a fixing ring and are also arranged circumferentially along the main shaft brake disc. The power supply is used to provide excitation current to each of the coils. The controller obtains the phase of each of the permanent magnets through the speed measurement unit and adjusts the excitation current of each coil to achieve blade speed control under the second operating condition.

[0008] Preferably, the speed measurement unit includes a bracket, a Hall chip, and a speed measuring magnetic ring. The speed measuring magnetic ring and the blade main shaft are arranged concentrically and rotate synchronously. The speed measuring magnetic ring causes the Hall chip to generate phase and speed signals and transmit them to the controller.

[0009] In any of the above solutions, it is preferred that a reserved gap is provided between the coils arranged along the main shaft, and the brake caliper of the first brake actuation component is fixedly installed at the gap.

[0010] In any of the above embodiments, it is preferred that each of the permanent magnets is connected to the edge of the main shaft brake disc by at least two bolts: The outer edge of the main shaft brake disc is provided with an annular groove, and each of the permanent magnets is embedded in the annular groove of the main shaft brake disc.

[0011] In any of the above schemes, it is preferred that the magnetic poles of the two circumferentially adjacent permanent magnets of the main shaft brake disc are opposite.

[0012] In any of the above embodiments, it is preferred that the fixing ring includes a clamp and a fixing surface, and the coil is disposed on the inner wall of the fixing surface.

[0013] In any of the above embodiments, it is preferred to further include a magnetic confinement assembly that cooperates with each of the coils. Each magnetic confinement assembly includes an iron core and a magnetically conductive baffle. One end of the iron core is connected to the fixed surface. The coil is wound around the outside of the iron core, and the magnetically conductive baffle is disposed on the outer periphery of the coil.

[0014] In any of the above embodiments, it is preferred that each of the permanent magnets is tilted and fixed to the outer edge of the main shaft brake disc, the two magnetic poles of each permanent magnet are set at an inclined angle with the circumferential tangential plane of the main shaft brake disc, and each of the coils is arranged at an inclined angle so that the magnetic circuit of each coil matches the tilt angle of the permanent magnet.

[0015] Another aspect of the technical solution of the present invention is: A method for controlling the blade speed of a wind turbine generator, using any of the aforementioned wind turbine generator blade speed control devices, includes the following steps: S1. The blade rotation speed signal and permanent magnet phase signal are collected in real time through the rotation speed measurement unit and transmitted to the controller; S2. The controller identifies the current operating condition and executes the corresponding control logic; The first working condition is the wind turbine inspection blade locking condition. The controller cuts off the coil excitation output, drives the brake caliper to move the brake pads to press against the friction part of the main shaft brake disc, and completes the mechanical locking of the blades. The second operating condition is when the blade speed is close to the rated maximum speed. The controller controls the power supply to output excitation current to the coil and adjusts the magnitude of the excitation current of each coil in real time according to the phase of the permanent magnet. The permanent magnet and the coil cooperate to generate a reverse electromagnetic damping torque to limit the blade overspeed.

[0016] Preferably, when a blade locking command is received, the controller controls the second braking actuator to perform a second operating condition, and the first operating condition mechanical locking braking is activated only after the wind turbine blade speed is reduced to a threshold.

[0017] The wind turbine blade speed control device of the present invention includes a first braking actuator and a second braking actuator. The second braking actuator relies on the magnetic field between a permanent magnet and a coil to achieve non-contact deceleration, eliminating mechanical friction and thus avoiding dry friction. The first braking actuator adopts a friction-fit structure, enabling stable braking.

[0018] The wind turbine blade speed control method of the present invention acquires the speed and phase signals of the wind turbine blades in real time and identifies the operating conditions to distinguish between two working modes. During the deceleration phase, the second braking actuator is activated. After the speed drops to the corresponding operating conditions, the coil excitation is cut off, and the system switches to the first braking actuator to complete the braking stop.

[0019] The two work together, relying on the dual-component structure and operating condition control logic, to achieve both anti-dry running and reliable braking. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of an embodiment of the wind turbine blade speed control device of the present invention.

[0021] Figure 2 This is a schematic diagram of an embodiment of the first brake actuator and the main shaft brake disc of the wind turbine blade speed control device of the present invention.

[0022] Figure 3 This is a schematic diagram of a preferred embodiment of the connection between the permanent magnet of the second brake actuator component and the outer edge of the main shaft brake disc in the wind turbine blade speed control device of the present invention.

[0023] Figure 4 This is an exploded view of the second brake actuator of the wind turbine blade speed control device of the present invention.

[0024] Figure 5 This is a schematic diagram of a preferred embodiment of the wind turbine blade speed control device of the present invention, showing the cooperation of the magnetic confinement component, coil, and fixed surface.

[0025] Figure 6 This is a schematic diagram of an embodiment of the frame of the wind turbine blade speed control device of the present invention.

[0026] Explanation of the labels in the diagram: 101-Clamping plate; 102-Fixing surface; 103-Frame; 104-Blade spindle; 105-Speed ​​measuring magnetic ring; 106-Spindle brake disc; 107-Hall chip; 108-Bracket; 109-Brake pad; 110-Brake caliper; 111-Permanent magnet; 112-Iron core; 113-Magnetic guide plate; 114-Coil. Detailed Implementation

[0027] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] In the description of this invention, terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0029] Example 1: This embodiment provides a wind turbine blade speed control device, such as... Figure 1 , 6 As shown, the blade main shaft 104 and the nacelle of the wind turbine generator set are assembled together. The nacelle of the wind turbine generator set is provided with a frame 103. The frame 103 serves as the mounting base for the first brake actuator and the second brake actuator of each component. The blade main shaft 104 passes through the through hole in the frame 103 and can rotate relative to the frame 103.

[0030] like Figure 1 As shown, this blade speed control device includes a speed measurement unit, a main shaft brake disc 106, a first brake actuation component, and a second brake actuation component. A flange is provided on the outer wall of the blade main shaft 104, through which the main shaft brake disc 106 is connected to the blade main shaft 104.

[0031] like Figure 1 As shown, the speed measurement unit is used to measure the blade speed and phase. One optional form of the speed measurement unit includes a bracket 108, a Hall effect chip 107, and a speed-measuring magnetic ring 105. The speed-measuring magnetic ring 105 is concentrically arranged on the surface of the main shaft brake disc 106 and rotates synchronously with the main shaft. The Hall effect chip 107 is fixed to the frame 103 by the bracket 108, maintaining a suitable distance from the speed-measuring magnetic ring 105. When the speed-measuring magnetic ring 105 rotates with the main shaft, it continuously cuts the sensing area of ​​the Hall effect chip 107, thereby causing the Hall effect chip 107 to generate real-time blade speed and phase signals. These two types of signals are ultimately transmitted to the controller of the device, providing data for the entire speed control mechanism.

[0032] like Figure 1 , 4As shown, the first brake actuator includes a brake pad 109 and a brake caliper 110. The brake pad 109 is mounted on the actuating end of the brake caliper 110, and a friction part that mates with the brake pad 109 is provided on the surface of the main shaft brake disc 106. The coils 114 of the second brake actuator are arranged circumferentially along the main shaft brake disc 106, with a reserved installation space between the coil 114 areas. The brake caliper 110 of the first brake actuator is then fixedly installed in the reserved space. The first brake actuator corresponds to the first operating condition of the device, which is mainly used in wind turbine equipment maintenance and scenarios where the blades are completely locked. During operation, the brake caliper 110 drives the brake pad 109 to press against the friction part of the main shaft brake disc 106. The mechanical friction between the contact surfaces brakes the main shaft brake disc 106, thereby achieving complete braking of the blade main shaft 104 and ensuring that the blades remain stationary during maintenance operations. Meanwhile, the equipment is set with linkage logic. The controller will only activate the first braking actuator to perform mechanical braking when the blade speed drops to the low speed range. This effectively avoids direct dry friction between the brake pads 109 and the main shaft brake disc 106 at high speeds, preventing rapid wear of components and impact on the equipment body due to sudden changes in speed.

[0033] The second brake actuation assembly includes multiple sets of permanent magnets 111, multiple coils 114, a power supply, and a controller. The permanent magnets 111 are evenly distributed circumferentially along the outer edge of the main shaft brake disc 106. In this embodiment, the magnetic poles of two adjacent permanent magnets circumferentially on the main shaft brake disc 106 are arranged in opposite directions. Each coil 114 is mounted at a fixing ring and connected to the frame 103 via the fixing ring. Similarly, to ensure force balance, each coil 114 is arranged correspondingly along the circumference of the main shaft brake disc 106. The power supply is responsible for supplying excitation current to all coils 114. Each coil 114 is wound with a single wire, and adjacent coils 114 are wound in opposite directions. After energization, the magnetic fields generated by adjacent coils 114 are opposite in direction, forming a stable magnetic fit with the corresponding permanent magnet 111.

[0034] Among them, such as Figure 4 As shown, the preferred form of the fixing ring includes a clamping piece 101 and a fixing surface 102. The coil 114 is disposed on the inner wall of the fixing surface 102. On the one hand, the clamping piece 101 can enhance the overall strength of the fixing ring. On the other hand, the coil 114 can be pre-wound around the inner wall of the fixing surface 102. After the coils 114 are arranged, the fixing surface 102 is fixed to the frame 103 by the clamping piece 101, which facilitates the assembly of the entire equipment.

[0035] The second braking actuator corresponds to the second operating condition of the device. This condition is suitable for wind turbines operating under low load, no-load conditions, and high external wind speeds. Under such conditions, the blades are prone to overspeeding. During device operation, the controller continuously receives the speed and phase signal of the permanent magnet 111 from the speed measurement unit. When the blade speed is detected to be close to the unit's rated maximum speed, the controller controls the power supply to output excitation current to each coil 114 and dynamically adjusts the magnitude of the excitation current of each group of coils 114 based on real-time phase data. Utilizing the interaction between the magnetic field generated by the energized coils 114 and the magnetic field of the permanent magnet 111, a reverse electromagnetic damping torque is formed, continuously counteracting the rotational power of the blade main shaft 104 and stabilizing the blade speed within the rated speed range. This electromagnetic speed regulation method is a flexible speed regulation method with no hard friction contact throughout the process. It can significantly reduce the frequency of use of mechanical braking components, avoid component wear caused by long-term dry friction, and make the blade speed change smoother, improving the stability of unit operation.

[0036] During normal operation of the wind power generation equipment, the speed measurement unit continuously collects the blade speed, main shaft, and permanent magnet 111 phase signals, and uploads them to the controller in real time. When the unit enters inspection or maintenance mode, or receives a blade locking command, the controller first determines the current blade speed. After the speed drops back to the safe low-speed range, it cuts off the excitation current of the coil 114 in the second braking actuator, exits the electromagnetic damping control state, and then drives the brake caliper 110 of the first braking actuator to actuate, causing the brake pad 109 to press against the friction part of the main shaft brake disc, thus locking the blades through mechanical friction. When the unit is under no-load or low-load conditions with high wind speed, and the blade speed continuously rises and approaches the rated maximum speed, the controller activates the second braking actuator. By adjusting the coil excitation current, it generates a continuous reverse electromagnetic damping torque to suppress the blade speed from continuing to rise, achieving overspeed protection. If the wind speed subsequently decreases, the blade speed drops back and leaves the overspeed range, the controller will gradually reduce the coil excitation current until it is completely de-energized, the electromagnetic damping effect disappears, and the blades return to normal operation.

[0037] Example 2: Based on Example 1, such as Figure 3As shown, during operation, the permanent magnets 111 rotate at high speed with the spindle brake disc 106 and are continuously subjected to centrifugal force, electromagnetic force, and vibration load. Each permanent magnet 111 is preferably made of neodymium iron boron. When the permanent magnets 111 are fixed to the edge of the spindle brake disc 106 with bolts, the torque of the bolts cannot be too large due to the brittleness of neodymium iron boron. To ensure that each permanent magnet 111 is firmly installed on the outer edge of the spindle brake disc 106, at least two bolts can be used to fix each permanent magnet 111 to the edge of the spindle brake disc 106. To further prevent angular displacement of the permanent magnets 111 relative to the spindle brake disc 106, an annular groove is formed on the outer edge of the spindle brake disc 106, and each permanent magnet 111 is correspondingly embedded in this groove. The ring groove embedding structure can effectively prevent problems such as loosening, displacement, and falling off of the permanent magnet 111, ensuring that the permanent magnet 111 is firmly installed and in a constant position under long-term operating conditions, thereby ensuring the stability of the electromagnetic damping torque output.

[0038] Example 3: Based on Example 1 or 2, such as Figure 4 , 5 As shown, in order to gather the coil magnetic flux, reduce leakage magnetic flux, increase the effective electromagnetic force of coil 114, and thus enhance the speed control effect under the second working condition, a magnetic constraint component is added to each coil 114 in this embodiment.

[0039] Specifically, the magnetic confinement assembly includes an iron core 112 and a magnetically conductive surrounding plate 113. One end of the iron core 112 is connected to the fixed surface 102, and a coil 114 is wound around the outside of the iron core 112. The magnetically conductive surrounding plate 113 is disposed on the outer periphery of the coil 114.

[0040] Both the iron core 112 and the magnetically conductive enclosure 113 are made of stacked silicon steel sheets. Silicon steel sheets possess excellent magnetic permeability, effectively concentrating coil flux, reducing magnetic leakage, and enhancing electromagnetic force. However, due to the material's brittleness and weak resistance to localized concentrated loads, an alternative connection between the iron core 112 and the fixing surface 102 is as follows: the iron core 112 has a through-hole along its own axis, and the fixing surface 102 is a conventional metal substrate. During assembly, fasteners pass through this through-hole to lock one end of the iron core 112 onto the fixing surface 102. A buffer insulating washer is installed between the fastener and the hole wall of the iron core 112 to evenly distribute the clamping force, preventing cracking of the silicon steel sheets due to stress concentration. Simultaneously, the pre-tightening force of the fasteners is strictly controlled to further mitigate the risk of component damage.

[0041] The end of the iron core 112 away from the fixed surface 102 has an integrally formed flange. This structure provides axial restraint for the coil 114 wound around the outside of the iron core 112, preventing the coil from shifting and loosening during equipment operation. The coil 114 is tightly wound around the outside of the iron core 112, and insulating adhesive is filled in the contact gap between the coil 114 and the iron core 112. After the adhesive cures, the two are fixed together as a whole.

[0042] A magnetically conductive enclosure 113 surrounds the outer periphery of the coil 114. The inner wall of the magnetically conductive enclosure 113 has a textured structure, which increases the bonding contact area and improves the bonding strength. Adhesive is filled between the inner wall of the magnetically conductive enclosure 113 and the outer surface of the coil 114. Through the interlocking action of the textured structure and the bonding effect of the adhesive, the magnetically conductive enclosure 113 and the coil 114 are firmly bonded. The iron core 112, the coil 114, and the magnetically conductive enclosure 113 ultimately form an integrated magnetic flux constraint structure, ensuring reliable assembly, stable magnetic circuit, and long-term adaptability to unit operating conditions.

[0043] Example 4: Based on any of the embodiments in Examples 1-3, this embodiment provides a detailed description of the inclined assembly structure of the permanent magnet 111 and coil 114 at the spindle brake disc 106. In conventional designs, if the permanent magnet poles and the coil 114 are kept perpendicular to the circumferential tangential plane of the spindle brake disc 106, the magnetic field force will be mainly distributed radially, which cannot be efficiently converted into a circumferential torque that hinders the rotation of the spindle. The utilization rate of magnetic field energy is low, and the control effect of electromagnetic damping will be greatly weakened.

[0044] Therefore, in this embodiment, as Figure 4 As shown, each permanent magnet 111 is tilted and fixed to the outer edge of the main shaft brake disc 106, so that the two poles of the permanent magnet 111 form a set tilt angle with the circumferential tangential surface of the main shaft brake disc 106. At the same time, the coils 114 corresponding to the permanent magnets 111 are also tilted and arranged synchronously to ensure that the magnetic circuit direction of the coils 114 is precisely matched with the tilt angle of the permanent magnets 111.

[0045] When the wind turbine is operating, the blades drive the main shaft, the main shaft brake disc 106, and the permanent magnet 111 on it to rotate continuously in a single fixed direction. In the inclined configuration, the electromagnetic force generated between the permanent magnet 111 and the coil 114 is obliquely distributed, and this force can be decomposed into a significant circumferential component. This circumferential component is opposite to the direction of rotation of the main shaft, and can continuously form a stable electromagnetic damping torque, which directly brakes and limits the speed of the rotating components.

[0046] This tilted matching structure changes the direction of the magnetic force, fully converting the energy generated by magnetic field coupling into an effective damping torque. Compared with the vertical arrangement, it significantly improves the efficiency of magnetic field utilization and the ability to control rotation speed.

[0047] Example 5: Based on any of the embodiments in Examples 1-4, this embodiment provides a speed control method. During the operation of the entire system, the speed measurement unit continuously undertakes the signal acquisition function. The speed measuring magnetic ring 105 rotates coaxially and synchronously with the blade main shaft 104. The Hall chip 107 is fixed on the bracket 108 of the frame 103, and collects two types of signals in real time: the real-time speed of the blade and the circumferential position and phase of each permanent magnet 111, and transmits the signals to the controller in real time. The controller, as the core computing and command output unit of the system, has built-in preset parameters, including a safe low-speed threshold, a rated maximum speed threshold, operating condition switching logic, phase matching rules, and a PWM modulation program. Based on the acquired signals, it completes operating condition determination, command issuance, and parameter adjustment.

[0048] In the first operating condition, namely the wind turbine blade locking condition, mechanical locking braking is achieved by relying on the first brake actuator. This condition is mainly used in unit maintenance and long-term fixed blade scenarios, and the system is set with speed interlock conditions.

[0049] When the controller receives the blade lock command, it does not directly activate the mechanical brake. The controller first continuously compares the measured speed with the preset safe low-speed threshold. Only when the blade speed drops to the safe low-speed range is the mechanical brake allowed to be activated. This avoids severe friction between the brake pads 109 and the main shaft brake disc 106 at high speeds, reducing wear and mechanical impact on the friction pair.

[0050] The sequence of actions is as follows: First, the controller sends a power-off command to the second brake actuator, cutting off the excitation power supply to all coils 114, exiting the electromagnetic damping speed regulation state, and ensuring that the magnetic field force is completely eliminated. Then, the controller drives the brake caliper 110 to move, causing the brake pads 109 to press against the friction part of the main shaft brake disc surface. Relying on mechanical friction, the main shaft brake disc 106 and the blade main shaft 104 are completely locked together, keeping the blade stationary and meeting the operational requirements.

[0051] When the lock is released, the controller controls the brake caliper 110 to reset, the brake pad 109 separates from the friction part, the blade main shaft 104 resumes rotation, and the system returns to the normal signal monitoring state.

[0052] The second operating condition, namely the electromagnetic damping control of the wind turbine blade speed, includes two implementation methods: speed limiting under normal overspeed conditions and controlled slow braking. The entire process relies on the second braking actuator. By determining the current direction through phase control and adjusting the current magnitude through PWM pulse width modulation, the electromagnetic damping torque is flexibly changed, achieving both stable speed control and gradual speed reduction. The speed regulation process is free of mechanical friction, resulting in smooth operation.

[0053] In this operating condition, the phase detection and current direction control principle is as follows: permanent magnets 111 are evenly distributed circumferentially along the outer edge of the main shaft brake disc 106, and adjacent permanent magnets 111 have opposite magnetic poles. The speed measurement unit captures the circumferential phase position of each permanent magnet 111 in real time and uploads the phase data to the controller.

[0054] The controller precisely matches the coil 114 at the corresponding position based on the current phase of the permanent magnet 111, and controls the direction of the excitation current inside the coil 114 to determine the polarity of the magnetic field generated by the coil 114. Only when the polarity of the coil magnetic field is precisely matched with the polarity of the corresponding permanent magnet magnetic field can the two generate a fixed opposing force, forming a damping torque that opposes the rotation of the blade.

[0055] In this embodiment, to achieve wind turbine blade speed adjustment according to a specific acceleration, the system employs PWM (Pulse Width Modulation) technology to continuously regulate the coil excitation current. PWM is a high-frequency, alternating pulse current output, where the pulse duration is the proportion of the entire cycle, called the duty cycle. The controller dynamically determines the PWM duty cycle based on the blade's real-time speed. By changing the duty cycle, the effective value of the excitation current is altered, thereby achieving two core regulatory functions: first, adjusting the magnitude of the electromagnetic damping constraint force; and second, controlling the rate of change of blade speed, i.e., speed regulation acceleration.

[0056] A larger duty cycle results in a larger average excitation current in the coil, a higher magnetic field strength, and a stronger reverse electromagnetic damping torque, leading to a more significant constraint and deceleration effect on the blades. Conversely, a smaller duty cycle results in a smaller excitation current, a weaker damping torque, and a smoother speed change. This adjustment method can be used to adapt to different speed control requirements.

[0057] In this embodiment, one implementation of the second operating condition is: normal overspeed limiting. This method is applicable to scenarios where the unit is generating electricity normally, the external wind speed is high, and the blade speed gradually approaches the rated maximum speed. Its function is to stably limit the speed within a safe range and prevent overspeed operation.

[0058] During normal operation, the speed measurement unit continuously collects speed and phase signals and uploads them to the controller. When the measured speed approaches the rated maximum speed threshold, the system automatically switches to this control mode.

[0059] The controller, in conjunction with the permanent magnet 111, locks the energizing direction of the coil 114 in real time and outputs a small-amplitude, dynamically fine-tuned PWM signal. By maintaining a moderate and slightly fluctuating duty cycle, it outputs a stable excitation current, forming a constant reverse damping torque to counteract excess rotational kinetic energy, prevent the speed from continuing to increase, and keep the blades always operating within the rated speed range.

[0060] As the outside wind speed decreases and the blade speed gradually drops and leaves the overspeed range, the controller gradually reduces the PWM pulse duty cycle, the effective value of the excitation current continues to decrease, and the electromagnetic damping torque decays synchronously and smoothly. This continues until the blade speed returns to the normal operating range, at which point the controller completely cuts off the power supply to coil 114, ending the control process.

[0061] Another implementation method for the second operating condition: controlled slow braking. This method serves as a flexible speed reduction transition means, used in scenarios where the unit needs to be gradually shut down and the speed needs to drop smoothly. It is a key buffer process before mechanical locking. When an instruction is received to shut down the entire unit and for the blades to be gradually braked, this mode is activated first. It relies on electromagnetic damping to complete the gradual speed reduction, avoiding the impact load caused by a sudden drop in speed.

[0062] After receiving the shutdown command, the controller maintains the phase detection and current direction logic unchanged, and gradually increases the PWM pulse duty cycle. The excitation current increases accordingly, the electromagnetic damping torque continuously increases, continuously consuming the blade rotational kinetic energy, and driving the blade speed to decrease smoothly.

[0063] The controller dynamically adjusts the PWM duty cycle based on the real-time speed throughout the process: when the speed is high, a larger duty cycle is used to increase the damping torque and accelerate the deceleration speed; when the speed gradually approaches the safe low-speed threshold, the duty cycle is gradually narrowed to reduce the damping effect and slow down the deceleration rhythm, so as to achieve a linear and smooth deceleration process without jitter or impact.

[0064] Once the speed drops to the preset safe low-speed range, this implementation method ends. The controller maintains the phase and current logic unchanged, continues to maintain the excitation output with a small delay, and after confirming that the speed is stable, gradually reduces the PWM duty cycle to zero, completely cutting off the power supply to coil 114, completing the entire electromagnetic deceleration process, and preparing for subsequent mechanical locking.

[0065] The above-described embodiments are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A wind turbine blade speed control device, comprising a speed measurement unit and a main shaft brake disc (106), characterized in that: The rotational speed measurement unit is used to measure the blade rotational speed and phase; The main shaft brake disc (106) is fixedly installed on the blade main shaft (104), and also includes a first brake actuation assembly and a second brake actuation assembly; The first braking actuator includes a brake pad (109) and a brake caliper (110). The brake pad (109) is mounted on the brake caliper (110). The main shaft brake disc (106) has a friction part on its disc surface that mates with the brake pad (109). The brake caliper (110) drives the brake pad (109) to achieve braking in the first working condition. The second brake actuation assembly includes multiple permanent magnets (111), multiple coils (114), a power supply, and a controller. The multiple permanent magnets (111) are evenly distributed circumferentially along the outer edge of the main shaft brake disc (106). The multiple coils (114) are fixedly connected to the frame (103) via a fixing ring and are arranged circumferentially along the main shaft brake disc (106). The power supply is used to provide excitation current to each coil (114). The controller obtains the phase of each permanent magnet (111) through the speed measurement unit and adjusts the excitation current of each coil (114) to realize blade speed regulation under the second working condition.

2. The wind turbine blade speed control device as described in claim 1, characterized in that, The rotational speed measurement unit includes a bracket (108), a Hall chip (107), and a speed measuring magnetic ring (105). The speed measuring magnetic ring (105) and the blade main shaft (104) are concentrically arranged and rotate synchronously. The speed measuring magnetic ring (105) causes the Hall chip (107) to generate phase and rotational speed signals and transmit them to the controller.

3. The wind turbine blade speed control device as described in claim 1, characterized in that, A reserved gap is provided between the coils (114) arranged along the main shaft, and the brake caliper (110) of the first brake actuator is fixedly installed at the gap.

4. The wind turbine blade speed control device as described in claim 1, characterized in that, Each permanent magnet (111) is connected to the edge of the main shaft brake disc (106) by at least two bolts: The outer edge of the main shaft brake disc (106) is provided with an annular groove, and each permanent magnet (111) is embedded in the annular groove of the main shaft brake disc (106).

5. The wind turbine blade speed control device as described in claim 1, characterized in that, The two circumferentially adjacent permanent magnets (111) of the main shaft brake disc (106) have opposite magnetic poles.

6. The wind turbine blade speed control device as described in claim 1, characterized in that, The fixing ring includes a clip (101) and a fixing surface (102), and the coil (114) is disposed on the inner wall of the fixing surface (102).

7. The wind turbine blade speed control device as described in claim 6, characterized in that, It also includes a magnetic confinement assembly that cooperates with each coil (114). Each magnetic confinement assembly includes an iron core (112) and a magnetically conductive enclosure (113). One end of the iron core (112) is connected to the fixed surface (102). The coil (114) is wound around the outside of the iron core (112), and the magnetically conductive enclosure (113) is disposed on the outer periphery of the coil (114).

8. The wind turbine blade speed control device as described in claim 7, characterized in that, Each permanent magnet (111) is fixed at an angle to the outer edge of the main shaft brake disc (106). The two magnetic poles of each permanent magnet (111) are set at an angle to the circumferential tangent of the main shaft brake disc (106). Each coil (114) is arranged at an angle so that the magnetic circuit of each coil (114) matches the tilt angle of the permanent magnet (111).

9. A method for controlling the blade speed of a wind turbine generator set, using the wind turbine generator set blade speed control device as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. The blade rotation speed signal and permanent magnet phase signal are collected in real time through the rotation speed measurement unit and transmitted to the controller; S2. The controller identifies the current operating condition and executes the corresponding control logic; Among them, the first working condition is the wind turbine inspection blade locking working condition. The controller cuts off the coil excitation output, drives the brake caliper (110) to drive the brake pad (109) to press the friction part of the main shaft brake disc (106) to complete the mechanical locking of the blade. The second operating condition is when the blade speed is close to the rated maximum speed. The controller controls the power supply to output excitation current to the coil (114) and adjusts the excitation current of each coil (114) in real time according to the phase of the permanent magnet (111). The permanent magnet (111) and the coil (114) work together to generate a reverse electromagnetic damping torque to limit the blade overspeed.

10. The wind turbine blade speed control method as described in claim 9, characterized in that, When a blade locking command is received, the controller controls the second brake actuator to perform the second operating condition. When the wind turbine blade speed drops to the threshold, the first operating condition mechanical locking brake is activated.

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