666 results about "Variable frequency control" patented technology

The invention discloses a frequency converter maintenance test system with a protection function, which belongs to the technical field of frequency converter testing and comprises a detection seat, a simulation unit for simulating actual working conditions of a frequency conversion control panel is arranged on the detection seat, and a detection mechanism for detecting a diode in the frequency conversion control panel is further arranged on the detection seat. Through dynamic cooperation of the polarization assembly and the rotary simulation disc, the vibration direction of the vibration source can be flexibly adjusted, so that a multi-dimensional vibration scene possibly encountered in actual work of the frequency conversion control panel is covered, and the problem that vibration source simulation is lacked in a traditional frequency converter testing process is solved; an elastic supporting environment of actual installation is simulated through the air bag spring suspension, vibration energy emission distortion caused by rigid fixation is avoided, the accuracy of a large-capacitance vibration fatigue test is improved, automatic step-by-step wiring operation of detection is achieved through cooperation of the detection driving assembly and the universal test meter, and the overall detection wiring efficiency is improved.

The utility model provides a full-bridge LLC resonant converter control circuit, which is characterized in that a full-bridge LCC resonant converter is provided with a frequency conversion controller, a phase shift controller and a mode switching module, the input end of the mode switching module is connected with an input voltage detection module, and when the input voltage of the full-bridge LCC resonant converter is lower than a preset threshold value, the phase shift controller is connected with the mode switching module. When the input voltage of the full-bridge LCC resonant converter is larger than or equal to a preset threshold value, the variable frequency controller controls a switching tube in the full-bridge LCC resonant converter to work through switching of the switch, and when the input voltage of the full-bridge LCC resonant converter is larger than or equal to the preset threshold value, the phase shift controller controls the switching tube in the full-bridge LCC resonant converter to work through switching of the switch. The full-bridge LLC resonant converter has the advantages that the variable-frequency controller and the phase-shift controller are arranged in the control circuit at the same time, switching of control modes can be achieved based on judgment of the magnitude of input voltage and through a simple switching circuit, the full-bridge LLC resonant converter has the advantages of variable-frequency control and phase-shift control, and the problems of voltage fluctuation and instability are solved.

The invention provides a two-phase refrigerator control system and method applied to electrochemical energy storage, the system comprises a two-phase refrigerator, a sensor and a controller, the two-phase refrigerator is composed of a cooling circulation pipeline, a refrigeration circulation pipeline, a plate heat exchanger and a liquid storage tank, the sensor is used for monitoring temperature and pressure, and the controller is used for controlling the temperature and the pressure. The controller accurately controls the system through the electromagnetic valve, the circulating pump, the compressor and the centrifugal fan. The control method is divided into a self-circulation mode and a refrigeration mode, automatic switching can be achieved according to temperature changes, and the cooling efficiency and stability are ensured. Through dual-mode intelligent and frequency conversion control switching, the cooling efficiency and the energy efficiency ratio are remarkably improved, and the problem that in the prior art, the cooling power of a two-phase liquid cooling machine is difficult to effectively control is effectively solved.

The utility model discloses a novel heat radiation structure driven by a variable frequency controller, which is mounted on a shell, the shell is provided with a first chamber for accommodating a fan and a second chamber for accommodating the variable frequency controller, and a partition plate is arranged between the first chamber and the second chamber; according to the heat dissipation structure, an air duct is connected with a variable-frequency controller, one end of the air duct communicates with a second cavity, and the other end of the air duct penetrates through a partition plate to communicate with a first cavity; the fan is matched with the air duct; the liquid cooling assembly is matched with the air duct; in a normal state, the air duct dissipates heat; at the first temperature, the air duct is matched with the fan to dissipate heat; at the second temperature, the air duct, the fan and the liquid cooling assembly are matched for heat dissipation; the second temperature > the first temperature > the normal state; according to the three modes, it is guaranteed that the driving temperature is within a proper range through structure optimization and control, and the application environment temperature of the whole unit is widened.

The invention relates to the technical field of industrial frequency conversion control, and discloses a fan frequency conversion energy-saving safety protection intelligent judgment system which comprises a multi-source data acquisition module, a multi-physics field coupling modeling module, a dynamic tensor decomposition module, a causal reinforcement learning control module, a dynamic closed-loop feedback module and a safety protection output module. The method comprises the following steps: modeling through multi-modal data fusion and multi-physical field coupling, extracting features in combination with tensor decomposition, generating a frequency conversion control instruction by utilizing causal reinforcement learning, and realizing closed-loop control of fan energy conservation and safety protection by dynamically adjusting a thermal diffusion coefficient and a residual hierarchical protection mechanism. According to the method, the monitoring capability is improved through multi-source data fusion and multi-field coupling modeling, energy-saving and safety collaborative optimization is realized in combination with tensor decomposition and causal reinforcement learning, a multi-stage protection system is constructed through closed-loop feedback, and the problems of multi-field dynamic unbalance and abnormal response lag of the frequency conversion fan are solved.

The invention provides an electromagnetic interference motor-driven frequency converter control method and system and a medium, and relates to the field of motor control, and the method comprises the steps: collecting an electromagnetic interference signal in real time during the operation of a motor-driven frequency converter, generating interference spectrum data, carrying out the dynamic switching adjustment of the frequency converter, and generating an anti-interference modulation instruction; reconstructing a pulse waveform according to the anti-interference modulation instruction to carry out harmonic compensation, carrying out feedback verification based on the optimized driving signal, carrying out electromagnetic interference judgment according to a motor torque fluctuation value, and generating a judgment result; and triggering a parameter updating instruction based on the judgment result, and driving a frequency converter to perform adaptive control through the parameter updating instruction to generate a frequency conversion control result. The technical problem that a frequency converter control method in the prior art is limited in resistance to electromagnetic interference and affects the running stability of a motor is solved. The technical effects of improving the electromagnetic interference suppression capability and ensuring the stable and reliable operation of the motor are achieved.

The invention relates to the technical field of general control systems, in particular to a water chilling unit energy-saving control method and system.The method comprises the steps that the machining process of a numerical control machine tool is equally divided into a plurality of monitoring time periods, and the demand degree of a water chilling unit in the machining process of the numerical control machine tool in the monitoring time periods is determined to screen out a target monitoring time period; energy consumption of the water chilling unit in the target monitoring time period is determined in combination with the time interval from the moment after the cutting temperature rises to the moment when the rotating speed of the compressor changes, and then the cooling effect of the water chilling unit in the target monitoring time period is determined in combination with rising changes of the cutting temperature and the environment temperature. And determining a regulation and control coefficient of the variable frequency driving control system in the target monitoring time period, and regulating and controlling the running speed of a compressor of the water chilling unit. The regulation and control coefficient for energy-saving control of the water chilling unit in the frequency conversion control system is obtained, and the operation speed of the compressor of the water chilling unit is regulated and controlled, so that the purpose of energy-saving control of the water chilling unit is achieved.

The invention discloses an intelligent variable-frequency tensioning device and a control method. The intelligent variable-frequency tensioning device comprises six units including a multi-modal data sensing and interaction integration unit and a self-adaptive variable-frequency driving execution regulation and control unit. The multi-modal data sensing and interaction integration unit collects tension, displacement and speed signals of operation of the tensioning device, the hierarchical parameter optimization processing center performs feature extraction and primary processing on data, and the intelligent algorithm collaborative decision module fuses an optimized PID control algorithm and an RBF neural network model to generate a control strategy. A motor is driven by the self-adaptive variable frequency driving execution regulation and control unit, the mechanical structure dynamic adjustment linkage unit is driven to adjust a tensioning part, and the state monitoring and feedback correction unit monitors in real time and feeds back data for strategy and parameter correction. According to the device and method, intelligent frequency conversion control of the tensioning device is achieved, control precision and system stability are effectively improved, and complex working condition requirements are met.

The invention relates to a current control method for a continuous casting blank stirrer, and the method comprises the steps: setting control parameters of a variable-frequency controller in an electromagnetic stirrer, enabling an actual current to rise to a target current value, controlling the current to be increased to a current oscillation upper limit value at a certain rate, and then enabling the current to be reduced to a current oscillation lower limit value at a certain rate, and the circulation is repeated, so that the continuous casting electromagnetic stirring current is changed in a periodic sinusoidal waveform. The electromagnetic stirring current is controlled to change in a periodic sinusoidal waveform, so that the carbon segregation of the casting blank is improved, the carbon segregation range of the casting blank is reduced, the internal components of the casting blank are more uniform, and the performance of the casting blank is improved.

The application provides a transient frequency conversion control method of a converter and an electronic device. The method comprises the following steps: determining the working state of the converter, wherein the working state comprises a light load working state and a heavy load working state; if it is determined that the working state switches between the light load working state and the heavy load working state, starting a transient frequency conversion control strategy to adjust the switching frequency of the converter, wherein the transient frequency conversion control strategy is used to adjust the duration of the freewheeling stage in the switching cycle of the converter; after the working state of the converter switches, and the clamping capacitor voltage sampling value of the converter v c satisfies a preset condition, exiting the transient frequency conversion control strategy to restore the switching frequency of the converter to normal. The dynamic response speed of the converter is effectively improved, and the overshoot and drop of the output voltage when the converter is subjected to a step load are reduced.

The invention relates to the technical field of tunnel equipment, and discloses a tunnel jet fan control method and system based on traffic flow and pollutant concentration, and the system comprises a data collection module, a data processing module, a control decision module, a jet fan control module and a jet fan frequency conversion controller which are in communication connection in sequence; the data acquisition module is used for acquiring traffic flow and pollutant concentration data; the data processing module is used for processing the traffic flow and pollutant concentration data to obtain processed data; the control decision module is used for generating a control instruction of the jet fan according to the processed data; the jet fan control module is used for converting the control instruction into a corresponding frequency control signal; and the jet fan frequency conversion controller is used for changing the power supply frequency of the jet fan motor according to the received frequency control signal so as to change the jet flow of the jet fan. According to the invention, the air quality in the tunnel can reach the standard, and the energy consumption can be effectively reduced.

The invention discloses an intelligent detection method and system for a variable frequency controller for an air conditioner, and relates to the field of intelligent detection, and the method comprises the steps: dynamically generating a test case set through an association rule mining algorithm based on a parameter data set of the variable frequency controller in a historical fault database; generating a test instruction set based on the test case set, and generating a digital simulation signal data stream; inputting the data flow into a variable frequency controller of the tested air conditioner, and synchronously acquiring output data of the variable frequency controller to form a real-time response data set; calculating a dynamic matching degree between the real-time response data set and fault data in a historical fault database, judging a potential fault, and tracing a fault cause label; and the newly identified fault data and the tracing result are uploaded to the historical fault database, and the association rule base is updated. The method has the advantages that potential faults of the variable-frequency controller of the air conditioner are accurately diagnosed through dynamic test case generation, real-time data matching and historical fault library updating, and the fault detection accuracy is improved.

The invention provides an intelligent frequency conversion control method and system. The method comprises the following steps: acquiring an environment parameter set and equipment operation data of intelligent equipment according to a preset multi-dimensional sensor; the method comprises the following steps: processing an environment parameter set and multi-dimensional parameters of equipment operation data to generate a multi-dimensional feature vector; constructing a neural network wind speed prediction model according to the multi-dimensional feature vector; dynamically adjusting a hidden layer node connection path of the wind speed prediction model to generate a dynamic wind speed set value; the wind speed deviation between the dynamic wind speed set value and the real-time wind speed and the discourse domain range of the deviation change rate are dynamically adjusted, and a PID parameter adjusting instruction is generated in combination with the fuzzy rule base; and generating a real-time adjustment parameter of the fan frequency of the intelligent equipment according to the PID parameter adjustment instruction. PID parameters can be dynamically adjusted under the condition of different wind speed deviations, it is ensured that the frequency of a draught fan is accurately adjusted, and therefore the dynamically-changing ventilation requirement is met.

The invention provides a method for improving transient stability of a submarine direct-current power supply system based on frequency compensation. The method comprises the following steps: acquiring a real-time electrical parameter detection item of a first system; based on the first system real-time electrical parameter detection item, judging whether the system load power is within a power range required by a transient stable operation condition; if not, the switching frequency compensation amount of the input-series output-parallel resonant converter sub-module is calculated; based on the switching frequency compensation amount, determining a switching signal of a sub-module switching tube of the input-series output-parallel resonant converter; acquiring a real-time electrical parameter detection item of a second system; based on a second system real-time electrical parameter detection item, judging whether the system load power is within a power range required by a transient stable operation condition; if yes, conventional frequency conversion control is adopted. The technical blank in the field is effectively filled, and the stability of the submarine direct-current power supply system in the transient process is remarkably improved.

The invention discloses a boost PFC circuit and method based on multi-mode frequency conversion sub-loop control, and relates to the field of power electronics. The PFC control circuit dynamically switches the DCM / MCM / CCM mode according to the load condition, and high PF and low THD are realized in a wide load range. The switching frequency of the PFC circuit is automatically adjusted according to the load, the input alternating current power supply voltage and the working mode, and smooth transition and quick response between different modes are achieved. The change of the switching frequency is beneficial to dispersing the harmonic energy of the switching frequency and reducing the electromagnetic EMI interference. In a CCM mode and an MCM mode, a PWM signal of a PFC switching tube is independently generated through a current control loop in the ring-dividing frequency conversion control technology, and a voltage control loop is only used for adjusting the duty ratio of the PWM signal, eliminating ripple interference of power frequency and reducing THD. The PFC control circuit realizes low THD and high PF performance in a wide working range by combining respective advantages of a multi-mode control method, a frequency conversion control method and a ring division control method.

The utility model relates to the technical field of motors, and particularly discloses a variable frequency motor, which comprises an inner shell, an outer shell and a frequency converter shell, a cooling part and a wire passing part are arranged on the outer side of the inner shell along the axial direction of the inner shell, the wire passing part is provided with a first wire passing hole for a three-phase wire to pass through, and the cooling part is provided with a cooling liquid groove. The groove wall of the cooling liquid groove and the inner side wall of the outer shell form a cooling liquid flow channel, cooling liquid flows in the cooling liquid flow channel, and at least part of the frequency conversion control panel is attached to the outer side of the outer shell, so that the stator and the frequency conversion control panel can be cooled through the inner shell and the outer shell respectively, the internal space of the inner shell does not need to be additionally occupied, and the axial size of the whole machine is small. And the method can be applied to more use scenes. The frequency converter shell covers the shell and is detachably connected with the shell, the frequency converter shell is provided with a containing space, the frequency conversion control panel is located in the containing space, and the first wire passing hole is communicated with the containing space. And the frequency conversion control panel can be maintained only by disassembling the frequency converter shell, so that the maintenance difficulty and the workload are reduced.

This invention provides a random frequency conversion control method for NVH (Noise, Vibration, and Harshness) of a motor controller in a pure electric vehicle. The method includes: simulating the full throttle pedal condition of the entire vehicle on an electric drive test bench to eliminate tire noise and wind noise interference, thereby obtaining a spectrum diagram of the NVH of the electric drive system at the IGBT base frequency under the full throttle pedal condition; analyzing the spectrum diagram to identify the prominent NVH noise range under the full throttle pedal condition, and using this prominent NVH noise range as the entry condition for random frequency conversion; establishing corresponding random frequency conversion models for different prominent NVH noise ranges based on the base frequency of the IGBT switching frequency, to perform random frequency conversion control on the prominent NVH noise ranges, and using the base frequency of the IGBT switching frequency for control in the non-prominent noise ranges. This invention can reduce the switching frequency noise of the motor controller and improve the NVH performance and safety of electric vehicles.

The invention provides a permanent magnet synchronous motor frequency conversion soft start and grid connection device and a control method. The device comprises a power supply grid (1), a permanent magnet synchronous motor (2), three-phase contactors (3), (4) and (5), a variable frequency controller composed of a rectifier (6), an inverter (7) and a control panel (8), a voltage sampling module (9), a current sampling module (10) and a filter inductor (11) at the output end of the inverter. One end of the three-phase contactor (3) is connected with a three-phase inlet wire of the power supply grid (1), and the other end of the three-phase contactor (3) is connected with the input end of the rectifier (6); one end of the three-phase contactor (4) is connected with the output end of the inverter (7), and the other end of the three-phase contactor (4) is connected with the input end of the motor (2); and one end of the three-phase contactor (5) is connected with a three-phase inlet wire of the power supply grid (1). VF open-loop pre-synchronization control is introduced in advance in vector control, power grid synchronization conditions are simulated, a motor is enabled to actively match power grid magnetic field parameters before grid connection, smooth transition of a control mode is realized, and large impact current and electromechanical oscillation are avoided.

The invention relates to the technical field of frequency conversion control, and particularly discloses an energy storage frequency conversion device and a charging and discharging control method.The energy storage frequency conversion device supports three-phase alternating current input and comprises a control part, a signal collecting and processing part, a main loop part and a battery part; the control part controls rectification, DCDC conversion and inversion of the energy storage frequency conversion device and charging and discharging of the battery part and is responsible for operation and processing of various collected signals. The signal acquisition and processing part comprises a three-phase input voltage acquisition module, a battery information acquisition module, a bus voltage acquisition module, a battery charging and discharging current acquisition module, an output current acquisition module, a DCDC driving module and a three-phase inversion driving module; the main loop part comprises a three-phase bridge type rectification part, a three-phase H-bridge inversion part and a DCDC part, and rectification, inversion and battery charging and discharging of the energy storage device are achieved.

The invention relates to the technical field of heat pump drying, and discloses a frequency conversion control drying method and a frequency conversion water source high-temperature drying heat pump unit which comprises a mounting bottom plate, a compressor arranged at the upper end of the mounting bottom plate and an air inlet pipe arranged at the upper end of the compressor. The dredging unit is arranged on the air inlet pipe and comprises an expansion part and an air inlet cleaning part which are arranged in the air inlet pipe; by arranging the dredging unit, when the compressor provides high-temperature gas to dry a metal material, once a filter screen in the compressor is blocked, the cleaning air inlet component can be automatically triggered through the expansion component, so that the cleaning air inlet component cleans the blocked filter screen, and normal air inlet and air outlet of the compressor are ensured; and continuous supply of hot air is ensured, the drying efficiency of the metal materials is improved, workers do not need to clean the filter screen regularly, and the labor cost and the maintenance difficulty are effectively reduced.

The embodiment of the invention provides an ultrasonic knife control method and device, medical equipment and a storage medium, an ultrasonic knife comprises a first piezoelectric vibration assembly and a second piezoelectric vibration assembly, the first piezoelectric vibration assembly is used for generating ultrasonic waves based on a resonance mode, the second piezoelectric vibration assembly is used for collecting the output frequency of the ultrasonic waves, and the output frequency of the ultrasonic waves is converted into the output frequency of the ultrasonic waves. The ultrasonic knife control method comprises the steps that when a frequency conversion control instruction is received, the jump frequency of the frequency conversion control instruction is determined; obtaining the output frequency; determining a target frequency in combination with the hopping frequency and the output frequency; and controlling the first piezoelectric vibration assembly based on the target frequency and the output frequency. The target frequency is determined through the hopping frequency based on the frequency conversion control instruction, frequency hopping control is conducted on the first piezoelectric vibration assembly, the characteristics of different vibration waves are output, and the using effect of the ultrasonic knife is improved.

The application discloses a traction transformer control cabinet and a rail train, and relates to the technical field of rail transit vehicles.The traction transformer control cabinet comprises a detachable shell and a control module arranged in the detachable shell; wherein the control module is used for determining the fan frequency of the fan in the cooling system of the traction transformer according to the first collection data sent by the whole vehicle controller of the rail train and the second collection data sent by the traction transformer, so as to utilize the fan frequency to perform frequency conversion control on the fan; the first collection signal comprises vehicle speed data, and the second collection signal comprises oil temperature data; through the arrangement of the traction transformer control cabinet, the control module in the traction transformer control cabinet performs frequency conversion control on the cooling fan according to the data such as the vehicle speed of the train and the oil temperature of the traction transformer, the low noise and the intelligentization of the traction transformer are realized, the noise of the rail train can be effectively reduced, and the passenger comfort is improved.

The invention relates to the technical field of centrifugal machines, in particular to a variable-frequency energy-saving automatic control system of a centrifugal machine, which comprises a centrifugal module used for separating materials according to the centrifugal machine to obtain a target product and comprising a driving motor used for providing centrifugal power; the data processing module comprises a data acquisition unit used for acquiring operation data of the centrifugal machine; the frequency conversion self-control module comprises a main MCU (Microprogrammed Control Unit) for outputting an adjusting strategy of the centrifugal machine according to a neural network model; the counting adjusting module is used for determining the counting frequency of the timer in the slave MCU according to the start-stop response duration of the driving motor; the feed-forward adjusting module is used for determining the feed-forward lead of the auxiliary motor according to the phase deviation value of the PWM signal; and the cache adjustment module is used for determining an operation data cache trigger threshold according to the slave MCU instruction response deviation duration. The real-time performance of frequency conversion self-control of the centrifugal machine is improved.

The utility model discloses a concrete vibrator with a built-in normal-pressure high-frequency motor special for equipment, and belongs to the technical field of engineering machinery. According to the technical scheme, the front end of a sleeve of the vibrator is connected with a pointed end through threads, and an oil cover, two sets of lower bearings, an oil seal cover, a coil inserting stator and a bearing seat are sequentially arranged in the sleeve; an upper bearing is arranged in the bearing seat, a rotor is supported by the lower bearing and the upper bearing, and an eccentric block and an oil suction pipe are arranged at the lower end of the rotor; the upper end of the sleeve is connected with an upper cover through threads, a wiring terminal and a wiring seat are arranged in the upper cover, a cable is fixed on the wiring terminal through a thread pair I, the cable is connected with a frequency conversion control cabinet fixed on equipment, and an electronic frequency converter and a grounding wire are arranged in the frequency conversion control cabinet. The upper cover is connected with four symmetrically-arranged rubber springs through a connecting pipe and a lower clamping plate and is connected with equipment through an upper clamping plate and an equipment connecting plate by using a thread pair II. The vibrator has the advantages of overcoming the defects of an existing vibrator for equipment, and being novel in design, reasonable in structure, safe and reliable.

The invention discloses a deep-well pump operation frequency conversion control method and system, and particularly relates to the technical field of liquid level automatic control. Based on the water level and the water level change rate, operation modes are intelligently judged and switched, and a dynamic water supply mode and a static maintenance mode are included; intelligent wakeup and protection are realized in a static maintenance mode; according to the sleep frequency self-learning algorithm, the sleep frequency and the wake-up water level are updated according to the real-time working condition; and multi-stage protection logic is integrated in the whole process. According to the invention, through the improved variable parameter PID control, the static maintenance and intelligent wake-up mechanism and the online self-learning ability, the system adjustment precision, the energy-saving effect and the adaptive ability are improved, and meanwhile, the reliability and safety of the system are enhanced through the multi-level protection logic.

The invention relates to the technical field of flow control and low-temperature engineering, in particular to a variable-frequency control-based flow range expansion method of a low-temperature flow standard device, which comprises the following steps of: acquiring basic working condition parameters and variable-frequency characteristic parameters of the low-temperature flow standard device through a parameter acquisition unit, and analyzing flow characteristics; a physical property parameter change rule and a flow characteristic comprehensive index are obtained, and a frequency conversion strategy is generated in combination with a frequency and flow characteristic curve; adjusting output frequency based on a frequency conversion strategy, and controlling pump rotating speed to perform flow expansion; the expansion result is verified, the expansion effect is judged, and after verification is finished, all verification results form a standardized document and are uploaded to a display terminal; the problem that continuous adjustment of the flow range from micro flow to medium and high flow is difficult is effectively solved, and the efficiency and stability of flow range expansion are improved.

The invention relates to the field of energy-saving optimization of data analysis, in particular to a building energy-saving optimization method and system based on big data analysis, and the method comprises the steps: obtaining the operation data of a cooling water system and a chilled water system, and generating a standardized time series data set in combination with the environment wet bulb temperature; a final evaporation temperature prediction value and a final condensation pressure prediction value are obtained through long-short-term memory network analysis, data analysis is conducted on the final evaporation temperature prediction value and the final condensation pressure prediction value and preset hard constraint conditions, and if the final evaporation temperature prediction value and the final condensation pressure prediction value both meet the preset hard constraint conditions, a comprehensive energy efficiency value is obtained through energy efficiency analysis calculation; iteratively solving a minimum comprehensive energy efficiency value meeting a hard constraint condition through an interior point method, outputting the frequencies of the corresponding cooling water pump and freezing pump as an optimal frequency instruction sequence, and sending the optimal frequency instruction sequence to a variable frequency controller; cooperative analysis of a cooling water system and a chilled water system can be effectively enhanced, the dynamic coupling relation between parameters is comprehensively considered, and the overall energy efficiency is improved.

The present invention discloses a refrigerator, a variable frequency compressor and a control method for a variable frequency compressor. The refrigerator includes a variable frequency compressor, an ambient temperature sensor and a variable frequency controller. After the variable frequency compressor is powered on, the current number of on-off cycles of the variable frequency compressor is determined in response to a preset operating parameter control instruction. If it is after N on-off cycles, the target start-up rate at the current ambient temperature is determined according to the current ambient temperature, and then the corresponding operating parameter adjustment rules are determined. According to the start-up rate of the variable frequency compressor in the previous on-off cycle and the operating parameter adjustment rules, the operating parameters of the previous on-off cycle are adjusted accordingly, and the variable frequency compressor is controlled to operate with the adjusted operating parameters when it starts running. By adopting the technical means of the embodiments of the present invention, the frequency adjustment of the variable frequency compressor can be effectively achieved, so that the variable frequency compressor can achieve better working efficiency, thereby providing users with a good user experience.

The invention provides a vacuum screw pump set control method. The method comprises the steps that a target value of the needed vacuum degree is input; obtaining an actual value of the vacuum degree of the equipment; obtaining a comparison result of the target value and the actual value; and according to the comparison result, the control system regulates and controls the operation frequency of the screw pump and the operation frequency of the roots pump. Compared with a single-frequency-conversion control method in the prior art, a double-frequency-conversion control method is adopted in the control method, the operation frequency of the screw pump and the operation frequency of the roots pump are controlled at the same time, so that the pumping speed range of the vacuum screw pump set is greatly expanded, and the pumping speed of the vacuum screw pump set is greatly increased through the control method under the condition that a pump body is not replaced. And the pumping speed adjusting range of an original pump set is expanded, so that the pump set can meet more pumping speed adjusting requirements, and an existing upgraded crystal pulling production process is further matched. And according to the comparison result of the actual value and the target value, a corresponding adjustment program is made, so that the vacuum degree in the equipment cavity can meet the requirement, and errors are reduced.

The invention relates to the field of oil extraction, in particular to a cable dropping and fishing electric heating system, and aims to solve the technical problems of high cost and influence on oil extraction aging of a thermal well washing technology. The dropping-fishing cable electric heating system comprises an oil pipe, a dropping-fishing cable, a wellhead device and a frequency conversion control cabinet, one end of the oil pipe is connected with the wellhead device; a steel wire layer of the throwing-fishing cable in the oil pipe is electrically connected with the oil pipe through an underground contactor; one end, penetrating out of the oil pipe, of the throwing-fishing cable is electrically connected with the frequency conversion control cabinet; and the frequency conversion control cabinet is also electrically connected with the wellhead device. The dropping and fishing cable electric heating system can replace hot well washing, water injection and drainage are not needed, wax is removed through electrifying and heating of the steel wire layer, and the oil extraction aging is guaranteed.