93results about How to "Improve power efficiency" patented technology

The invention discloses a multi-underwater-robot cooperative control system and method based on predictive control, and relates to the technical field of cooperative control. During operation of the system, underwater environment data are collected through sensor equipment, an underwater three-dimensional dynamic environment model is generated by using a data fusion technology, and the underwater three-dimensional dynamic environment model is established based on task requirements; tasks are decomposed and distributed to all the robots, through an optimization algorithm, optimal paths of the robots and the mechanical arms are planned, the motion trails of the underwater robot mechanical arms are dynamically optimized based on model predictive control MPC, a real-time control strategy is provided for task division among the multiple mechanical arms, and the real-time control strategy of the underwater robot mechanical arms is provided based on environment modeling and the real-time state. Future motion states of the robot and the mechanical arm of the robot are predicted, an optimization objective function including task completion time, energy consumption and mechanical arm operation precision is constructed, a rolling optimization method is utilized, a control instruction is updated in real time, and real-time data sharing among multiple underwater robots is supported based on an acoustic communication technology.

The invention provides a physical layer secure antenna selection method based on an MIMO-NOMA system, and relates to the technical field of information security. According to the method, a downlink MIMO-NOMA communication system is established, two kinds of safety antenna selection strategies are designed, the received signal power of legal users is maximized, and the signal power of eavesdropping user receivers is minimized; and the unmanned aerial vehicle transmits the superposed signal, the user receives the signal and decodes the received signal, then the traversal rate of the legal user is solved, and the probability of successfully decoding the transmission information is reduced for the potential eavesdropping user. According to the method, the antenna selection strategy is optimized, the received signal power between the source node and the legal user is maximized, the probability that the eavesdropping user successfully decodes the legal signal is reduced, and the secrecy performance of the system can be improved while the service quality of the legal user is ensured.

The invention relates to the technical field of exoskeletons, in particular to a high-degree-of-freedom light lower limb assisting exoskeleton. The invention provides a high-degree-of-freedom light lower limb assisting exoskeleton. The high-degree-of-freedom light lower limb assisting exoskeleton comprises a back assembly, a waist assembly, hip joint motors, thigh assemblies, knee joint motors, shank assemblies and ankle joint and foot assemblies which are sequentially connected. Wherein the thigh assembly comprises a hip joint motor connecting piece, a thigh rod and a knee joint motor connecting piece which are connected in sequence, and the end, close to the hip joint motor connecting piece, of the thigh rod is hinged to the hip joint motor connecting piece through a first hinge shaft. The multi-degree-of-freedom hip joint mechanism and the multi-degree-of-freedom knee joint mechanism are adopted, so that the exoskeleton can better coincide with contour curves of all parts of a human body and better adapt to complex movement of human joints, and the problems that the exoskeleton is poor in wearing comfort, effective assisting force is lost and the like due to man-machine discordance are solved.

The anti-wrinkle mechanism of the sock turn-over device is applied to the technical field of sock turn-over, the driving part is arranged to drive the rotating disc to rotate, socks are driven to be switched among the fixing part, the turn-over part and the wrinkle removing part, the fixing part and the clamping block are arranged, the socks can be automatically fixed in the rotating process of the rotating disc, and the sock turn-over efficiency is improved. According to the sock overturning device, the overturning piece is arranged, the overturning rod moves to extrude socks to achieve overturning, meanwhile, suction force is generated on the socks through the draught fan, the socks are assisted to be overturned, the phenomenon that the socks are overturned unsuccessfully is avoided, wrinkles of the socks are preliminarily removed, and the wrinkle removing piece is arranged to drive a piston rod and a piston barrel to move and enter the sock overturning barrel; and then the piston is driven to move in the piston barrel to enable the air bag to expand, the socks are comprehensively expanded, wrinkles are comprehensively removed, the extrusion rod is arranged to synchronously move along with the piston rod, fixation of the socks is relieved after the wrinkles of the socks are comprehensively removed, and automatic collection of the socks is achieved.

The invention provides an X-ray photovoltaic radiation cell based on a gallium-containing semiconductor and a preparation method of the X-ray photovoltaic radiation cell. The gallium-containing semiconductor X-ray radiation photovoltaic cell comprises a gallium-containing semiconductor transduction unit and an X-ray radiation source 55Fe arranged on the semiconductor transduction unit, wherein the semiconductor transduction unit containing gallium comprises at least one of GaAs (gallium arsenide), GaInP (gallium indium phosphide), GaP (gallium phosphide) and Ga2O3 (gallium trioxide). According to the invention, the structure of a radiation photovoltaic cell is adopted, the output power density of an X-ray radioactive source 55Fe can be effectively improved, the penetration depth of the X-ray source 55Fe in a semiconductor can be effectively shortened by taking GaAs, GaInP, GaP and Ga2O3 as semiconductor materials, and meanwhile, the collection capability of current carriers is effectively improved by adjusting the total thickness of a semiconductor transduction unit and the doping concentration of each layer, so that the performance of the X-ray source 55Fe is improved. And finally, the preparation of the X-ray radiation photovoltaic cell with high output power and high energy conversion efficiency is realized.

The clamp spring assembling tool is used for assembling a clamp spring into a clamping groove in a connecting rod so as to limit a bearing into a bearing groove in the connecting rod, the clamp spring assembling tool comprises a ring sleeve and a push rod, the ring sleeve is coaxially provided with a hole body, the hole body comprises a positioning section and a pushing section which are communicated with each other, and the push rod is arranged in the positioning section. The diameter of the positioning section is gradually decreased towards the pushing section in the axial direction of the positioning section, the diameter of the push rod is matched with the diameter of the pushing section, the push rod can axially slide in the pushing section, the maximum inner diameter of the clamping spring is smaller than the diameter of the push rod, and a positioning column with the diameter matched with the inner diameter of the bearing is coaxially arranged at one end of the push rod. According to the clamp spring assembling tool, the assembling difficulty is lowered, the assembling success rate and the working efficiency are improved, and damage to the clamp spring during assembling is reduced.

The invention relates to the technical field of unmanned aerial vehicles, and discloses an unmanned aerial vehicle rotor device which comprises an arm assembly, a motor assembly, a damping assembly, a folding paddle assembly and a folding paddle limiting assembly, when an unmanned aerial vehicle needs to work, folding paddles in the folding paddle assembly are unfolded in parallel, and the folding paddle limiting assembly is fixed to paddle pressing pieces through a quick release mechanism in a matched mode; the folding blades are clamped between the limiting blocks, and the parallel unfolding state of the folding blades is fixedly kept. At the moment, when the motor assembly is started to output power torque, the folding blades cannot deviate due to uneven stress, and large vibration cannot be generated and transmitted to the unmanned aerial vehicle body and application equipment. And meanwhile, the damping assembly is in a working state, the damping rubber sleeve obstructs and filters vibration generated by rotation of the motor assembly and the folding paddle assembly, and the vibration is effectively prevented from being transmitted to an unmanned aerial vehicle body and application equipment. The invention further provides the unmanned aerial vehicle comprising the rotor wing device.

The present invention discloses a multi-dimensional analysis system for existing user archives based on power image recognition, including an integration layer, a business layer and a service layer; wherein the business layer includes a customer archive digitization unit, an archive digitization business application unit, a residential archive maintenance management unit, a customer archive digitization analysis unit, a customer archive public support management unit, an i State Grid app function optimization unit, an online State Grid app function optimization unit and an electronic archive security management unit. The present invention can solve the existing problems of not realizing the onlineization of the entire process of business expansion archives, and being in a weak position in terms of OCR recognition verification, unstructured data retrieval, and contract encryption capabilities. The present invention effectively improves the efficiency of customers' electricity handling, promotes online business, improves the level of customer interactive service management, improves the level of digital decision-making assistance, enhances the ability to mine data value, empowers corporate business decisions, and fully realizes maximum benefits.

The invention relates to the technical field of stator core production, in particular to a brushless motor stator core full-automatic production line which comprises a first punching mechanism, a second punching mechanism, a first feeding mechanism, a second feeding mechanism, a lamination conveying mechanism, an assembling jig, a welding mechanism and a discharging mechanism. The first punching mechanism is used for punching a first stator iron sheet, the second punching mechanism is used for punching a second stator iron sheet, the first feeding mechanism is used for grabbing a first stator iron sheet punched by the first punching mechanism and placing the first stator iron sheet on the assembling jig to be assembled into a first stator iron ring, and the second feeding mechanism is used for grabbing the second stator iron sheet punched by the second punching mechanism and placing the second stator iron sheet on the assembling jig to be assembled into a second stator iron ring. And stacking the first stator iron rings placed on the assembling jig to form a second stator iron ring. Through the design of high automation and integration, the production efficiency is remarkably improved, and the product quality is stable and reliable.

The invention relates to the technical field of stator core production, in particular to a motor stator core automatic processing and forming method, which comprises a first punching mechanism, a second punching mechanism, a first feeding mechanism, a second feeding mechanism, a lamination conveying mechanism, an assembling jig, a welding mechanism and a discharging mechanism, the first punching mechanism is used for punching a first stator iron sheet, the second punching mechanism is used for punching a second stator iron sheet, the first feeding mechanism is used for grabbing a first stator iron sheet punched by the first punching mechanism and placing the first stator iron sheet on the assembling jig to be assembled into a first stator iron ring, and the second feeding mechanism is used for grabbing the second stator iron sheet punched by the second punching mechanism and placing the second stator iron sheet on the assembling jig to be assembled into a second stator iron ring. And stacking the first stator iron rings placed on the assembling jig to form a second stator iron ring. By means of a series of automatic and precise processing steps, efficient, precise and stable production of the stator iron core is achieved. According to the method, the production efficiency is improved, the production cost is reduced, and the quality and reliability of products are remarkably improved.

The utility model provides an electronic paper point screen crimping device which comprises at least one group of crimping modules and specifically comprises a driving module which comprises an X-direction driving mechanism and a Y-direction driving mechanism, and the Y-direction driving mechanism is arranged on the X-direction driving mechanism; the crimping module is installed on the Y-direction driving mechanism and comprises an opening-closing type driving mechanism, an upper crimping assembly and a lower crimping assembly, the upper crimping assembly and the lower crimping assembly are symmetrically arranged in the vertical direction, and the opening-closing type driving mechanism drives the upper crimping assembly and the lower crimping assembly to move oppositely or reversely; each of the upper crimping assembly and the lower crimping assembly comprises a fixed part, a floating part and a buffer structure connected with the fixed part, a probe is arranged in the fixed part, and the floating part is provided with a through hole for the probe to pass through; when the distance L1 between the upper crimping assembly and the lower crimping assembly is reduced to L2, the floating part pre-flattens the crimping end of the to-be-crimped product and completes correction and alignment; the buffer structure deforms, so that the floating part stops moving and the fixed part continuously moves until the upper probe and the lower probe are in contact with the surface of the product; and the visual unit is arranged above the crimping module. And the crimping precision and accuracy are improved.

This invention provides a multi-stage, multi-angle, rapid diffusion oxygen dissolving three-dimensional non-clogging microbubble aerator. An air inlet pipe and an air pipe are sequentially connected along the air inlet direction. A rapid microbubble cutting and diffusion oxygen dissolving unit is fitted outside the air inlet pipe. An inner cylinder and an outer cylinder are sequentially fitted outside the air pipe from the inside to the outside. The inner cylinder has a first inner cylinder section, a second inner cylinder section, and a third inner cylinder section sequentially along the air inlet direction. A medium-sized bubble cutting and diffusion oxygen dissolving unit is installed on the outer wall of the first inner cylinder section, a large bubble cutting and diffusion oxygen dissolving unit is installed on the outer wall of the second inner cylinder section, and an air guiding unit is installed on the outer wall of the third inner cylinder section. An air diffuser unit is installed at the air outlet of the air pipe. This multi-stage, multi-angle, rapid diffusion oxygen dissolving three-dimensional non-clogging microbubble aerator effectively cuts air into microbubbles, effectively solving the problems of clogging and short lifespan of traditional aerators after long-term use, and is suitable for aerobic aeration treatment.

A display device and an electronic device are disclosed. The display device includes a substrate including a display area and a peripheral area; first to eighth pixels disposed in the display area of the substrate and disposed side by side in a first direction; a first gate driver disposed in the peripheral area of the substrate and sequentially applying a gate write signal to each of the first to eighth pixels along the first direction; and a second gate driver disposed in the peripheral area of the substrate, separated from the first gate driver in a second direction intersecting the first direction, and including a gate initialization part applying a gate initialization signal to at least two of the first to eighth pixels simultaneously, and an emission controller applying an emission control signal to at least two of the first to eighth pixels simultaneously and disposed adjacent to the gate initialization part in the first direction.

This invention discloses an HPAM-DMT-NOMA method based on time-domain preprocessing, comprising: At the transmitting end, PAM modulation is performed on the input user transmission bits to generate PAM symbols; after power superposition, serial-to-parallel conversion, and Hermitian symmetry, the symbols are allocated to two signal components for HPAM-DMT transmission; the frequency domain signals of PAM-DMT and RPAM-DMT are calculated; an IFFT operation is performed to obtain the time domain signal; the time-domain preprocessed signal is calculated; the RPAM-DMT time domain signal is calculated and superimposed on the clipped PAM-DMT signal for synchronous transmission to obtain a mixed signal; a reconstructed signal is introduced, processed, and input to drive an LED for illumination; at the receiving end, the received signal is processed to generate a frequency domain signal, and finally, the multi-user signal is recovered. This scheme eliminates clipping noise interference between the mixed signal components, avoids error propagation problems, and achieves high spectral efficiency and power efficiency.

This application belongs to the field of wireless charging technology, specifically relating to a constant current and constant voltage wireless charging system and method based on a three-coil loosely coupled transformer, including an inverter circuit, a primary-side compensation circuit, a resonant circuit, a secondary-side compensation circuit, a rectifier circuit, and a filter capacitor; the resonant circuit has an anti-parallel coil structure, with the third coil located on the secondary side and a single coil on the primary side; its advantages are high misalignment tolerance, load-independent output, and high efficiency.

Embodiments of the present disclosure relate to a display device and, more particularly, may protect a color filter layer by including a substrate, a light emitting layer disposed on the substrate, an encapsulation layer disposed on the light emitting layer, a first color filter disposed on the encapsulation layer, and a first protective layer overlapping the first color filter.

Provided is an electrolyte membrane including at least the following: an A-layer composed of an ion-conducting fluorinated polymer and a non-ion-conducting fluorinated polymer; and a B-layer composed of an ion-conducting hydrocarbon polymer, wherein the ion-conducting hydrocarbon polymer is dispersed in the A-layer. Provided is an electrolyte membrane having excellent oxidation resistance. In addition, provided is an electrolyte membrane for a redox-flow battery, in which the electrolyte membrane used as a barrier membrane for a redox-flow battery makes it possible to achieve high power efficiency and stable charge and discharge even in long-term use.

The present invention provides a dual-power steam turbine, which is composed of a steam turbine and a fuel engine. A heat exchanger is arranged on the fuel engine casing, the engine manifold, the outside of the engine cylinder, or any part of the engine exhaust outlet to convert the engine waste heat into high-pressure steam; the steam turbine air inlet is connected to the high-pressure steam outlet of the heat exchanger and the exhaust port of the fuel engine to form a dual-power steam turbine. The present invention increases the thermal efficiency of the fuel engine to more than 60%, saves more than 20% of fuel, and reduces exhaust emission pollution by more than 60%; it is not only applicable to ground engines but also to sea and air engines; it fundamentally solves the problems of low efficiency, high fuel consumption, and serious pollution of fuel engines; it makes the fuel engine an energy-saving and environmentally friendly engine.

The invention relates to the technical field of integrated circuits, in particular to a laser radar receiving front-end circuit, an optical circuit and a chip, the circuit comprises a total input end, a total output end, an input module, an intermediate module and an output module, the input module comprises a first input end, a first output end, a first power connection end and a first grounding end; the intermediate module comprises a second input end, a second output end, a second power connection end and a second grounding end; the output module comprises a third input end, a third output end, a third power connection end and a third grounding end; the first input end is electrically connected with the total input end, the first output end is electrically connected with the second input end, the first power connection end is electrically connected with the second grounding end, and the first grounding end is grounded; the second output end is electrically connected with the third input end, and the second grounding end is electrically connected with the third grounding end; the third output end is electrically connected with the total output end, and the third power connection end is connected with a power supply. The circuit is low in power consumption and high in current efficiency.

This utility model discloses a voltage holding circuit, including: a rectifier bridge unit, a PFC unit, and an LLC unit; the PFC unit includes: a boost module, capacitor C1, capacitor C3, a first switch Q4, a second switch Q5, and a control module; the output terminal of the rectifier bridge unit is connected to the input terminal of the boost module and the first terminal of the second switch Q5; the second terminal of the second switch Q5 is connected to the first terminal of capacitor C3 and the first terminal of the first switch Q4; the second terminal of capacitor C3 is connected to the first terminal of capacitor C1; the second terminal of the first switch Q4 is connected to the second terminal of capacitor C1, the output terminal of the boost module, and the input terminal of the LLC unit; the control module is connected to the first switch Q4 and the second switch Q5. This voltage holding circuit has the advantages of high component utilization and low power loss. While extending the power-down hold time, it can also improve power efficiency and has good application prospects.

A light emitting diode (LED) array comprising: a plurality of pixels, each of the pixels comprising a respective group of light emitting diodes (LEDs), the plurality of pixels comprising: a first group of pixels configured to emit a first red primary wavelength; a second group of pixels configured to emit a first green primary wavelength; a third group of pixels configured to emit a first blue primary wavelength; the first red primary wavelength, the first green primary wavelength, and the first blue primary wavelength defining an RGB (red-green-blue) color gamut; and a fourth group of pixels configured to emit a non-white emission comprising a higher luminous efficacy than any of the first group of pixels or the third group of pixels to increase power efficiency of the device.

This invention discloses an isolated, fully soft-switching AC-DC-AC converter with primary and secondary side co-multiplexing and a modulation method. The converter includes a front-stage AC-DC converter, an intermediate-stage full-bridge LLC resonant converter, and a rear-stage DC-AC converter. This invention multiplexes the primary-side bridge arm of the full-bridge LLC resonant converter with the output bridge arm of the front-stage AC-DC converter, and the secondary-side bridge arm with the input bridge arm of the rear-stage DC-AC converter, forming an integrated AC-DC-AC converter structure, thereby reducing the number of components. Simultaneously, it employs PWM and phase-shift modulation strategies to control the inductor current of the four-transistor Buck-Boost circuit into a quadrilateral inductor current, thus achieving soft switching of all switching transistors. This topology is suitable for isolated AC conversion scenarios, enabling soft switching of switching devices, electrical isolation, wide-range voltage regulation, and effectively reducing the number of components. It also offers advantages such as high power density, high conversion efficiency, and high reliability.

The utility model discloses a circuit structure of an electronic hookah. The circuit structure comprises an MCU main control module, a driving module, a heating module, a temperature control module and a power supply module for supplying power to the electronic hookah, the heating module is composed of a heating wire and a heating piece which are electrically connected with the driving module. According to the scheme, by arranging the MCU main control module, the driving module, the heating module, the temperature control module and the power supply module for supplying power to the electronic hookah, the temperature of a tobacco bowl or hot airflow in the electronic hookah can be monitored in real time, so that the heating power of a heating wire and a heating piece can be adjusted in time, tobacco burning or equipment overheating is prevented, and the use experience of a user is guaranteed; and moreover, by adjusting the heating power and controlling the temperature, the inhalation of harmful substances can be reduced. Meanwhile, the heating module is composed of a heating wire and a heating piece, a single heating source is not adopted any more, the tobacco materials are heated more evenly, the smoke taste is richer, and the smoking experience of a user is improved.

The invention provides a lithium ion solid-state battery electrode material and a preparation method thereof, and the preparation method comprises the following steps: adding a nitrogen source and a carboxyl auxiliary ligand into a metal salt solution, and carrying out a heat sealing reaction to obtain a coordination metal cluster; mixing the cellulose derivative and the functional organic group, and carrying out polymerization reaction to obtain a copolymer matrix; dissolving the coordination metal cluster and the copolymer matrix in a lithium salt solution, and carrying out a cross-linking reaction to obtain a composite solution; and adding an electrode active material into the composite solution, uniformly stirring, defoaming, coating on a current collector, and drying to obtain the lithium ion solid-state battery electrode material. Therefore, the cycle life and conductive efficiency of the battery are improved.

The invention relates to a cluster distributed virtual interrupt control method, device and system. The method comprises the following steps: under the condition that a first distributed virtual interrupt controller DVIC node receives a virtual interrupt request, determining interrupt target routing information corresponding to virtual interrupt; the first DVIC node constructs a cross-chip hardware-level direct injection message according to the interrupt target routing information; and the first DVIC node sends a hardware-level direct injection message to the second DVIC node through inter-chip interconnection, and the hardware-level direct injection message directly writes a virtual interrupt into an IMSIC interrupt file of an incoming message signal interrupt controller through hardware logic by the second DVIC node. According to the invention, the cross-chip virtual interrupt delivery delay can be obviously reduced, and the system certainty is improved.

The invention discloses a system complexity optimization method for a low-altitude large-scale MIMO (Multiple Input Multiple Output) fusion network, which is characterized in that a base station with M antennas and randomly distributed single antenna users are arranged in a large-scale MIMO system based on a downlink angular domain. All users are divided into K groups after user scheduling, and each group has # imgabs0 # users. It is assumed that a base station knows a channel set and corresponding channel response information in advance. An approximate information transfer algorithm is adopted to obtain a precoding design for reducing high PAPR (Peak to Average Power Ratio). In addition, the invention further provides a novel optimization iteration scheme based on the optimal mean square error minimization principle, and the scheme is used for reducing the PAPR in the angular domain under the condition that the finite set is considered. The method has an important application value for reducing the peak-to-average power ratio of a large-scale multiple-input-multiple-output communication system.

The invention provides a multi-layer combined wind collection vertical wind power generation system, a wind power system comprises a multi-layer wind power machine which is detachably mounted, a wind collection protection system is slidably mounted on a wind collection plate slideway outside a fan frame body, and a wind collection and refraction channel is formed between the wind collection protection system and a fan blade assembly; the fan blade assembly is installed on the wind turbine shaft at an angle, and the fan blade assembly and the wind turbine shaft are installed in the fan frame. The generator set comprises a protection frame body, one or more sets of speed increasers, a generator set body and an intelligent controller, wherein the speed increasers and the generator set body are arranged in the protection frame body. The intelligent controller controls the opening and closing angle of the wind collection protection system and the output voltage and grid connection of the wind turbine generator set, so that the air supply amount of the wind power machine is adjusted, and then the wind flow is controlled to be refracted to the fan blade assembly to generate rotation driving torque under the action of the wind collection and refraction channel; the fan blade assembly is pushed to horizontally rotate along the wind motor shaft, and then the transmission assembly is driven to drive the speed increaser and the generator to operate for power generation.

The utility model provides a kind of jacking rotary code scanning device, it is related to battery production technical field.Jacking rotary code scanning device includes first driving part, mounting piece, transmission part and second driving part.The output end of first driving part is connected with mounting piece, for driving mounting piece to lift, the number of transmission part is multiple, multiple transmission parts are movably arranged in mounting piece and are sequentially transmission connection, the output end of second driving part is connected with any one transmission part, for driving multiple transmission parts to rotate, transmission part is used to drive battery to rotate, to this is conducive to identification mechanism accurate identification battery, and by driving battery to rotate can effectively avoid the problem that identification mechanism cannot be identified due to battery surface reflection light influence identification mechanism cannot be identified.Obviously, the jacking rotary code scanning device provided by the utility model embodiment is high in degree of automation, and significantly improves identification success rate and production efficiency.

This invention relates to the field of oil and gas extraction engineering, and discloses a retrieval tube for coiled tubing operations that can determine the retrieval status. The retrieval tube includes an upper connector, a sliding rod, a spring, a slider, a connecting tube, slips, and a guide shoe tube. The slips are used to hold the fallen fish. The mechanical cooperation between the slider and the sliding rod causes a change in the opening and closing state of the fluid channel inside the tool after the fish is retrieved, resulting in a significant increase in the surface pump pressure, which is used to determine the retrieval status. This invention has a simple structure and can determine whether a fallen fish has been retrieved simply by changing the pump pressure, avoiding the uncertainty caused by relying on experience-based judgment. It is suitable for downhole retrieval operations in coiled tubing.

The present invention provides a power tool, including: a power supply unit; a brushless motor, including a stator and a rotor; an inverter circuit, including a plurality of switch components, where the plurality of switch components are configured to perform a switch action to control driving of the brushless motor; and a controller, electrically connected to the inverter circuit and the brushless motor, the controller including a load detection module configured to detect a parameter indicating a workload of the brushless motor; where when the parameter is less than a set threshold, the controller controls the brushless motor to maintain a first target rotational speed; when the parameter is greater than or equal to a set threshold, the controller controls the brushless motor to maintain a second target rotational speed; and the first target rotational speed is greater than the second target rotational speed. A motor rotational speed of the power tool is controlled to maintain a lower second target rotational speed, so that the power tool is prevented from being damaged due to large fluctuations in the motor rotational speed under a heavy load. The motor rotational speed of the power tool is controlled to maintain a higher first target rotational speed, so that working efficiency of the power tool is improved before entering a heavy load state.