810 results about "Variable frequency control" patented technology

The invention provides a multi-region independent temperature control intelligent frequency conversion refrigeration and preservation method and system, and relates to the technical field of refrigeration and preservation. A region division module, a temperature control module, an environment monitoring module, a data analysis module, an intelligent frequency conversion control module and a user interface module work cooperatively; fine temperature control management of different areas in the refrigeration equipment is realized, the system adopts three-dimensional laser scanning and multispectral image acquisition technologies to automatically divide temperature areas, a quantum-level precision thermistor array and an intelligent fuzzy PID controller ensure accurate temperature control, and meanwhile, humidity and air flow are monitored to optimize a storage environment, so that the temperature control efficiency is improved. The data analysis module is combined with deep learning and an association rule mining algorithm to provide decision support for frequency conversion control and realize energy consumption optimization, the user interface module provides visual operation experience, and the whole scheme improves the intelligence, accuracy and energy efficiency of refrigeration and preservation, and is suitable for various cold chain scenes.

The invention relates to the technical field of tunnel ventilation control, in particular to a tunnel fan energy-saving control system which comprises a multi-parameter sensing module, an intelligent evaluation module, a dynamic prediction module, an energy-saving optimization module, a frequency conversion control module and an alarm emergency module. Wherein the multi-parameter sensing module is used for monitoring various environmental parameters in a tunnel in real time; the intelligent evaluation module is used for calculating the current ventilation demand; the dynamic prediction module is used for predicting the ventilation demand in a period of time in the future; the energy-saving optimization module is used for generating an optimal energy-saving control instruction; the frequency conversion control module is used for adjusting the operation frequency and speed of the fan according to the instruction; and the alarm emergency module is used for sending an alarm signal when an abnormal condition is detected. According to the invention, environmental parameters in the tunnel are monitored and intelligently managed in real time, a fan operation strategy is dynamically optimized, and the system has emergency response capability, so that the ventilation efficiency is remarkably improved, the energy consumption is reduced, and the construction safety is guaranteed.

The invention relates to the field of machine room water pump control methods, in particular to an efficient machine room water pump frequency conversion control system and method. Modules of intelligent prediction and optimization, dynamic pressure and flow control, multi-sensor fusion, fault prediction and adaptive control, energy management and optimization and the like are integrated; and prospective and self-adaptive operation of the cooling system is realized. The system not only can predict the cooling demand according to historical data and real-time environmental parameters and adjust the working state in advance, but also can monitor and accurately control the pressure and flow of the cooling water system in real time and ensure the cooling efficiency. Through multi-sensor fusion, the system comprehensively monitors the operation state, and in combination with fault prediction and adaptive control, potential faults can be prevented, and the system stability is guaranteed. The energy management and optimization module intelligently dispatches operation of a cooling water tower fan and a cooling water pump, efficient utilization of energy is achieved, and the energy efficiency and reliability of the cooling system are remarkably improved on the whole.

The invention discloses an intelligent frequency conversion control method, device and system based on dynamic data acquisition, and the method comprises the steps: obtaining the electromagnetic parameter waveform of a motor in real time, carrying out the deep analysis of features through a machine learning algorithm, and achieving the recognition of the abnormal recognition precision; synchronously acquiring a rotor position and an evaluation parameter set, executing an exception analysis strategy, generating a risk evaluation coefficient, and accurately locking an exception moment; in the process, through a synergistic effect of quantizing angle deviation, current abnormity and sampling delay, a mathematical framework is provided for fault prediction, and risks are reduced in the acquisition process; and under the condition that the risk assessment coefficient is received, the risk assessment coefficient and a preset assessment threshold are compared and analyzed, and whether a corresponding frequency conversion control instruction is executed or not is selected according to a comparison result, so that high-precision and high-efficiency intelligent frequency conversion control on the motor is realized.

The invention relates to the technical field of frequency conversion control, and discloses a frequency conversion control method and system for a nuclear power station ventilation system, and the method comprises the steps: collecting the multi-region real-time operation data of the nuclear power station ventilation system, and carrying out the standardization processing, and obtaining a standardized data set; performing fan performance curve fitting and differential pressure field feature mapping on the standardized data set to obtain differential pressure field mapping features; the differential pressure field mapping features are input into an active neural differential pressure field network model for frequency conversion parameter prediction, and target frequency conversion control parameters are obtained; feedforward-feedback combined control is conducted on the target frequency conversion control parameters through the multi-mode frequency conversion controller, the fan rotating speed and the air valve opening value are obtained, the target frequency conversion control parameters can be generated in a self-adaptive mode, the control performance is remarkably improved, and smooth transition of the nuclear power station ventilation system is achieved.

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 an intelligent control system and an intelligent control method of a bridge girder erection machine, and relates to the technical field of bridge construction application, the intelligent system comprises a plurality of variable frequency controllers which are respectively installed on a front support and a middle support, a front crown block and a rear crown block, and a rear support, the variable frequency controller controls the rotating speed of the transverse moving motors of the front support and the rear support, the rotating speed of the walking motors of the front crown block and the rear crown block and the rotating speed of the front and rear running motors of the middle support and the rear support according to a control instruction of the PLC control system. The rotating speed of the motor is controlled through the frequency converter, so that the left-right moving synchronism of the front support and the middle support of the bridge girder erection machine is effectively controlled, the walking synchronism of the front crown block and the rear crown block on the left and right wheels on the track is effectively controlled, and derailment caused by inconsistent speeds of the wheels on the two sides of the track is avoided.

The invention provides a variable-frequency control method and system for noise of an exhaust system of a transformer substation room based on a genetic algorithm, and the method comprises the steps: collecting the temperature and noise data of the transformer substation room in real time through a distributed sensor network, and building a multi-target optimization model through the genetic algorithm in combination with a variable-frequency speed regulation technology; and the noise and the temperature are used as constraint conditions to be jointly solved with an optimization target. The genetic algorithm dynamically adjusts the operation frequency of the exhaust fan through the operations of population initialization, fitness evaluation, selection, crossover, variation and the like, so that the requirements of temperature control and noise minimization are balanced. The rotating speed of the exhaust fan can be adjusted in a self-adaptive mode. Compared with a traditional single-machine fixed wind speed or simple linkage control method, the technology can remarkably improve the comprehensive energy efficiency of the system, reduce energy waste and improve the operation environment of the transformer substation room. The technology is suitable for noise and temperature control requirements of various types of indoor transformer substations and similar scenes, and has high applicability and popularization value.

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 relates to the technical field of electro-hydraulic control, and discloses an emulsion pump station frequency conversion control system which comprises an emulsion pump station, a pump station initialization subsystem, a fault detection subsystem, a pressure sensor, a controller, a frequency conversion device, an emulsion pump station switching subsystem, an emulsion pressure setting subsystem and an emulsion main pipeline. The invention further provides an application method of the emulsion pump station frequency conversion control system. The application method comprises the following steps that S1, a program is initialized; the emulsion supply efficiency of the fully mechanized coal mining face of the coal mine can be improved, the liquid supply pressure can be stabilized, the power consumption in the liquid supply system can be reduced, the service life of frequency conversion control system equipment of the emulsion pump station can be prolonged, automatic control of the emulsion pump station can be realized, the labor cost can be reduced, and the working efficiency and reliability can be improved; unnecessary property loss is reduced, and important technical guarantee is provided for efficient and safe production of the coal industry and stable development of the coal industry.

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 present invention discloses an outdoor variable frequency control cabinet, which belongs to the field of variable frequency control cabinets, including a cabinet, a hinge fixedly connected to the outer surface of the front end of the cabinet, a cabinet door hingedly connected to the cabinet by the hinge, a protective component arranged on the outer surface of the cabinet, the protective component comprising a bracket fixedly connected to the outer surface of the upper end of the cabinet, the number of the brackets being two groups and being parallelly distributed left and right, the brackets being in a trapezoidal structure, and a protective plate fixedly connected to the outer surface of the upper end of the bracket. By setting a dehumidification component, it can be achieved that when air enters the interior of the cabinet, it will fully contact with the silica gel plate, and the silica gel plate can effectively absorb moisture in the air, thereby greatly reducing moisture entering the cabinet, and further effectively reducing the probability of condensation forming in the cabinet, improving the safety of the control cabinet during operation, and reducing the rust of the control cabinet and its internal electrical components caused by condensation.

The invention relates to the technical field of cooling system control, in particular to a ship central cooling water system frequency conversion control simulation analysis system, which comprises a dynamic load prediction module for predicting cooling load requirements of ship main engine and auxiliary engine equipment in different time periods in the future in real time; the load grading control module is used for dividing loads into a plurality of grades, including light load grades, medium load grades and heavy load grades, and generating multi-layer frequency conversion control strategies for cooling water requirements under different load grades; the amplitude control module optimizes the variation amplitude of the rotating speed of the water pump; the load peak value regulation and control module is used for carrying out short-time overclocking control on the water pump when the load fluctuates violently within a short time; and the load distribution simulation module is used for simulating behaviors and responses of the cooling system under different load conditions by performing simulation analysis on distribution of loads of all cooling loops in the ship cooling water system. According to the invention, it is ensured that the equipment obtains sufficient cooling support under a high-load condition, and the load adaptive capacity and the operation efficiency of the cooling system are effectively improved.

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 an intelligent defrosting method and system for energy-saving variable-frequency refrigeration and fresh-keeping equipment, relates to the technical field of refrigeration and fresh-keeping equipment, and realizes accurate and efficient defrosting operation by integrating an acquisition module, a calculation module, a judgment module, a control module, a hot fluorine defrosting module, an ultrasonic cavitation jet module and an AI visual detection module. Indoor return air temperature and evaporator outlet surface temperature can be collected in real time, the frosting temperature difference is calculated, whether defrosting is needed or not is judged according to the temperature difference, a self-adaptive defrosting control strategy is adopted, the optimal defrosting time and area are selected, energy consumption is reduced, a hot fluorine defrosting technology is combined with frequency conversion control, and heat productivity and warehouse temperature fluctuation are reduced. According to the ultrasonic cavitation jet technology, frost falling is accelerated through sound pressure, the water-saving and environment-friendly defrosting effect is achieved, the AI visual detection module integrates multiple technologies to accurately measure a frost layer, decision support is provided for the control module, and the system improves the defrosting efficiency and reduces energy consumption.

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.

The invention belongs to the field of motor control, and discloses a frequency conversion control method and device for current sampling. The method comprises the following steps: acquiring the current rotating speed of the direct current motor, the current carrier period duration and a plurality of components of the carrier period; determining a vector angle and a vector modulus length of the current control voltage according to the current rotating speed; determining the component duration of each component in the current carrier period duration according to the vector angle, the vector modulus length, the preset maximum included angle, the current carrier period duration and the standard component modulus length; based on a pre-stored sampling duration threshold and the plurality of component durations, determining a sampling method of the direct current motor in the current carrier period, and judging whether the duration of the current carrier period is adjusted or not; according to a sampling method, single / double-phase current of the direct current motor is obtained, three-phase current reconstruction is carried out through the Kirchhoff's law, and target three-phase current of the direct current motor is obtained. By adopting the method, the obtained three-phase current of the direct current motor can be more accurate.

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 utility model relates to the technical field of electromagnetic station cooling, and aims to provide an electromagnetic station micro-positive pressure control device which comprises a frequency converter chamber installed on a cable trench, and a plurality of frequency conversion control cabinets connected with cables in the cable trench are arranged in the frequency converter chamber. The two outer side walls, corresponding to the frequency conversion control cabinet, of the frequency converter chamber are each provided with a plurality of dustproof air purifying fans, the bottoms of the side walls, corresponding to the dustproof air purifying fans, of the frequency conversion control cabinet are provided with air inlet grilles, and the dustproof air purifying fans enable the interior of the chamber to be kept in a micro-positive pressure state through air inlet. According to the utility model, cold air is blown into the high-voltage frequency conversion chamber by adopting the dustproof air purifier, cold and hot air exchange can be carried out on electrical elements in the high-voltage frequency conversion chamber, and the exchanged hot air is exhausted by the exhaust pipe, so that the indoor environment is kept in a micro-positive pressure state; the stability of indoor temperature can be kept through the air conditioning unit, and stable operation of equipment is guaranteed.