1144 results about "Three phase asynchronous motor" patented technology

Wind power installations generally have an active drive for wind direction tracking. The active drive rotates the machine housing of the wind power installation in such a way that the rotor blades of the rotor are oriented in the direction of the wind. Multiple azimuthal drives are typically used for larger wind power installations. The present invention includes a wind power installation comprising a machine housing, a rotor with at least one rotor blade, and a displacement device for orientating the rotor in the direction of the wind. The displacement device has a three-phase asynchronous motor drive that is supplied with three-phase current and is at times or completely acted upon with direct current during the stoppage time of the machine housing. Thus improved displacement devices, such as azimuthal drives, are provided ensuring uniform load distribution for each drive and preventing unwanted torque fluctuations in the individual drives.

The invention discloses a parameter off-line identifying method of a three-phase asynchronous motor. Through the current output by an inverter, the connecting method of the three-phase winding of a motor is equivalent to the terminal current of a phase winding, which is detected by a sensor when any two phase windings are connected in parallel and then are connected with the other phase winding in series every time, thereby obtaining the direct voltage and the direct current or the alternating current voltage and the alternating current of the motor winding; the impedance of reverse gamma equivalent circuit of the motor is calculated by the alternating voltage and the alternating current, and then the equivalent rotor resistance, the total leakage inductance and the equivalent mutual induction parameter of the motor are calculated by two impedances under the condition of different frequencies omega 1 and omega 2. The method disclosed in the invention can indentify the motor parameter without the rotation of the motor, thereby avoiding the empty load test required in the process of identifying parameters in prior arts, enlarging the application scope of indentifying the motor parameter and improving the accuracy of the identified motor parameters. The method and the device of the invention are applicable to the motor parameter off-line identification of a three-phase asynchronous motor speed control system controlled by an inverter.

The invention discloses a spatial three-dimensional translational degree of freedom (DOF) combination drive flexible cable parallel mechanism which comprises four groups of combination drive double-crank five-connecting link mechanisms which are arranged symmetrically in a cross way, a cable support tower bracket, and flexible cables which are respectively connected with the four groups of combination drive double-crank five-connecting link mechanisms and used for drawing a weight block. Each combination drive double-crank five-connecting link mechanism comprises a three-phase asynchronous motor, a servo motor, a speed reducer, a pulley transmission mechanism, and a double-crank five-connecting link mechanism; the cable support tower bracket comprises four stand columns, cable support tower upper beams and cable support tower lower beams which are respectively connected with the four stand columns; and each stand column is provided with a flexible cable leading sheave. The combination drive mechanism combined by two drive mechanisms integrates the high efficiency and the high bearing capacity of a traditional mechanism and the adjustable flexibility of the servo drive mechanism and makes up the defects that the traditional drive mechanism is lack of flexibility and the servo drive mechanism can not bear large load; therefore, the combination drive mechanism has the advantages of the high efficiency and the high bearing capacity of the traditional mechanism and the adjustable flexibility of the servo drive mechanism.

The invention discloses an oil-tea camellia fruit picking robot which comprises a chassis, a chassis driving system and a control system, wherein the chassis driving system is used for driving the chassis to move. A picking arm and a visual identification system are arranged on the chassis, and a vibration picking head is arranged at the tail end of the picking arm. A three-phase asynchronous motor, an electric control cabinet and a generator are arranged on the chassis, wherein the three-phase asynchronous motor is used for providing power to the chassis driving system, the electric control cabinet is used for controlling the picking arm and the visual identification system, and the generator is used for providing electric power to an oil-tea camellia fruit picking machine. The control system comprises a control computer which is used for controlling the picking arm to carry out the picking operation and automatically finish the picking process of oil-tea camellia fruits through information, such as positions, sizes and the like of oil-tea camellia fruit trees, collected by the visual identification system. According to the oil-tea camellia fruit picking robot, the control computer is utilized to intelligently control the visual identification system and a picking arm set to automatically finish the oil-tea camellia fruit picking operation, and is high in integration level and automation degree, good in picking environment suitability and coordination among mechanisms, capable of ensuring continuity of picking motion, high in picking efficiency, convenient to maintain and strong in practicability.

Disclosed is an anti-interference and comprehensive protection device for a low voltage three-phase asynchronous motor, which can realize the restarting of the low voltage three-phase asynchronous motor when the motor is shut down by the fluctuation of the low voltage power network, thereby solves the problem that the product line of industry manufacture enterprise can be shut down abnormally by the power-shaking. The invention is composed of the follows: 1, a processor, 2, a clock chip, 3, a battery, 4, a voltage comparator circuit, 5, a monitor circuit of a contactor, 6, a control circuit of a relay 7, a second control loop, 8, a switching power supply, and 9, a wire connection terminal. The invention can restart the motor when the power is switched on after the motor is shut down due to the power-shaking of the power network, can distinguish two different failures of power-shaking and long-time under-voltage, and can judge whether the motor is working before power-shaking. The anti-interference and comprehensive protection device of the invention has the advantages of high setting accuracy, good repeatability and accurate action time, and does not need external equipment to provide high power backup power supply.

The invention discloses a shoemaking automatic buffing and gel spraying processing device with five degrees of freedom, which is realized mainly through a mobile mechanism and a rotation mechanism. The mobile mechanism can control the movement of a work piece at three space orthogonal positions. A buffing head mechanism or a gel spraying mechanism is respectively connected with an arm swinging binding part. The rotation of a swing arm and a buffing head box or a spray gun is respectively driven through an AC servo motor, which leads to that the buffing plate or the spray gun can swing along two orthogonal directions to realize the posture regulation of the buffing plate or the spray gun. A three-phase asynchronous motor drives the buffing plate to rotate at a high speed through a flexible shaft to realize the buffing work. The automatic buffing and the gel spraying work can be respectively realized through different connections of the buffing head mechanism or the gel spraying mechanism with the arm swinging combining part.

The invention discloses an impulse type grain mass flow sensor calibrating and testing device, which relates to the field of grain mass flow sensor calibrating and test machines. The impulse type grain mass flow sensor calibrating and testing device comprises a machine frame (1), a net rice elevator (3), a hopper A (2), a hopper B (19), a rotating speed sensor (4), a vibration sensor (7), a tilt angle sensor (9), a hopper scale (18), a grain flow sensor mounting position adjusting device, a grain mass sensor mounting position adjusting device, three vibration motors, a three-phase asynchronous motor (26), four frequency converters, a high-speed camera acquisition system (6), a monitoring storage system and four wheels. The impulse type grain mass flow sensor calibrating and testing device is simple in mounting and is convenient to detach and move. After an impulse type grain flow sensor is calibrated on the testing device, the impulse type grain flow sensor can be directly arranged on a combine harvester to operate.

The invention provides a force amplitude adjustable type vibration absorber actuating mechanism which is based on a double-slider mechanism. One end of two parallel rotating shafts is respectively provided with mutually meshed straight spur gears, a connection shaft of a three phase asynchronous motor drives the straight spur gear of a driving parallel rotating shaft, right ends of the two rotating shafts are connected with sliding-block linkages with the same structure, the sliding-block linkage includes a connecting rod, adjusting sliders and an eccentric mass slider; the adjusting slider is connected with the parallel rotating shaft, the eccentric mass slider is sheathed on a slide bar which is vertical to the parallel rotating shaft, two adjusting sliders are connected by a deflector rod which is connected with a regulating mechanism, a driven parallel rotating shaft is connected with a first straight tooth bevel gear which is meshed with a second straight tooth bevel gear on a worm, a turbine, which is meshed with the worm, is arranged above the worm, the center of the turbine is connected with a first drive bolt, and the actuating mechanism further includes a second drive bolt. The actuating mechanism can be used for reducing mechanical vibration caused by unbalanced force and torque to improve mechanical vibration amplitude.

The invention relates to a medium-sized high-voltage three-phase asynchronous motor. A front end cover and a rear end cover are installed at both ends of a casing; a stator is installed in the casing, fixed on the front end cover and the rear end cover, and connected with a junction box; a rotor is located in the casing, the front end and the rear end of the rotor are respectively installed on the front end cover and the rear end cover through a front bearing assembly and a rear bearing assembly, and the front bearing assembly and the rear bearing assembly are respectively fixed by an external bearing cover, an internal bearing cover, a bearing retaining ring and a V-shaped ring; an external fan is installed at the rear tail end of the rotor and is fixed by the bearing retaining ring; a fan housing is fixed on the rear end cover and covers the external fan; and a key is installed in a key slot at the front end of the rotor. The medium-sized high-voltage three-phase asynchronous motor is characterized in that the rotor is also provided with an internal fan, the internal fan is located inside the casing and fixed by the bearing retaining ring, and the internal fan, a rotor ventilating slot and a ventilation passage on the casing form an internal circulating cooling wind path. The invention has compact and reasonable structure, good heat dispersion, low operation noise, high strength, and safe and reliable operation.

The invention discloses an intelligent electrically-driven cable arranging device of a marine winch. The device is that two groups of three-phase asynchronous motors are respectively connected with a power supply through transducers and are connected with a main shaft of a roller through a planetary gear; a permanent magnet synchronizing motor drives a rolling lead screw supported by a bearing to rotate by speed reduction through a speed reducer; the rolling lead screw drives a cable guide wheel to move leftwards and rightwards on a guide rail; a cable is arranged on the roller through a cable width sensor and the cable guide wheel; a first proximity switch and a second proximity switch are respectively mounted at two ends of the rolling lead screw; signals detected by a roller rotating speed detecting photoelectric encoder, a motor rotating speed photoelectric encoder and a photoelectric encoder are respectively input to an intelligent controller; the intelligent controller controls the working states of the three-phase asynchronous motors and the permanent magnet synchronizing motor. The device has the advantages of being good in cable arranging effect, reliable to work, high in real-time performance, automatic to adjust the working state according to the cable width, and capable of continuously working under a complex marine working environment.

The invention discloses a reliability test bed which can perform axial and radial dynamic loading for simulating actual work conditions on a mechanical connecting fastener. The mechanical connecting fastener reliability test bed is mainly composed of a vibration power source, a dynamic loading and measuring mechanism and a workbench mechanism, wherein the vibration power source is connected with a shaft of the dynamic loading and measuring mechanism through a connecting rod; the workbench mechanism is connected with a stud B of the dynamic loading and measuring mechanism; the vibration power source comprises a three-phase asynchronous motor, a motor holder, an eccentric bushing, the connecting rod and a deep groove ball bearing; the dynamic loading and measuring mechanism comprises the shaft, a linear bearing box-type unit, a linear bearing support, a tension and pressure sensor, the stud and an elastic unit. The mechanical connecting fastener reliability test bed achieves control over dynamic loading amplitude of the fastener by adjusting a stud mechanism, can detect the magnitude of the dynamic loading force in real time and simulate the actual work conditions and is concise and practical in control and adjustment method and wide in application range.

The invention relates to an energy-consumption braking control module of a three-phase asynchronous motor, comprising a power supply unit, a single chip control unit and a braking direct-current voltage output unit, wherein direct-current voltage output by the braking direct-current voltage output unit is transmitted to a two-phase stator winding of a motor when the motor stops so as to generate braking torque. The energy-consumption braking control module of a three-phase asynchronous motor is characterized in that the single chip control unit detects the work state of the motor by the work conduction angle of the voltage output unit, and a preset program controls the size of the conduction angle so as to regulate the output time and magnitude of the direct-current voltage required by braking. The energy-consumption braking control module of a three-phase asynchronous motor also comprises a zero cross signal detection unit, a running state detection unit, a winding temperature detection unit and a braking current detection unit, wherein each unit respectively outputs a corresponding signal transmitted to the single chip control unit for processing. The invention adopts integrated IC, has little used elements, compact structure, independent products and convenient installation and use and is beneficial to popularization and application; and the single chip is flexible to control, the intellectualized degree is high, and the braking of the motor is safe and stable.

The invention discloses an identification method for the abnormal state of a three-phase asynchronous motor at an industrial site; energy efficiency assessment is selected for carrying out abnormal state identification if the output power of the three-phase asynchronous motor can be directly measured at the industrial site in an on-line mode; characteristic parameter discretion is selected for carrying out abnormal state identification if the characteristic quantity representing the operation of the three-phase asynchronous motor can be directly measured; physical model discretion is selected for carrying out abnormal state identification if a physical model can be established according to a measured value; and predicting model discretion is selected for carrying out abnormal state identification when above conditions are all not applicable. Compared with a currently used empirical method, the method has scientificity and practicability, thus being convenient for an enterprise to grasp the operation state of the three-phase asynchronous motor, helping the enterprise to evaluate when the three-phase asynchronous motor enters an accident-prone period, and further enhancing the enterprise monitoring on the three-phase asynchronous motor and preventing safety loophole.

The invention discloses an observing and compensating method of disturbance in three-phase asynchronous motor complexor controlling slave system, which is characterized by the following: combining disturbance observer (DOB) and PID controlling method; inhibiting disturbance in the system; adopting di-closed-loop structure of position loop and electric current loop for slave system; designing disturbance observer (DOB) in the position loop faced to electric current loop; adopting PI to control for the electric current loop; adopting PD to control for the position loop. This invention possesses simple realization, simple method and easy control, which disturbance observer (DOB) possesses the advantages of quick response and separate adjustment.

A method for the identification without shaft encoder of magnetomechanical characteristic quantities of a three-phase asynchronous comprising: constant voltage impression U1α in α axial direction in order to generate a constant magnetic flux; test signal voltage supply U1β in β axial direction of the asynchronous motor, whereby the α axial direction remains supplied with constant current; measuring signal current measurement I1β in β stator axial direction of the asynchronous motor; identification of mechanical characteristic quantities of the asynchronous motor based on the test signal voltage U1β and on the measuring signal current I1β, whereby the rotor can execute deflection movements. Method can also be used for control of electrical drives. An identification apparatus for the determination of mechanical characteristic quantities of an asynchronous motor and for motor control, whereby the identified characteristic quantities can be used to determine, optimize and monitor a motor control.

The invention relates to a low voltage high-power three-phase asynchronous motor. According to the technical scheme of the invention, a front end cover and a back end cover are installed at both ends of a motor base, a stator is installed in the motor base, and is fixed on the front end cover and the back end cover, the stator is connected with a junction box, a rotor is installed in the motor base, the front end and the back end of the rotor are installed on the front end cover and the back end cover by a front bearing and a back bearing, the front bearing and the back bearing are fixed by an external bearing cover, an internal bearing cover and a bearing retainer ring, an external fan is installed at the tail end of the rotor and is fixed by the bearing retainer ring, an external fan shield is fixed on the back end cover, and a key is installed in a key slot at the front of the rotor. The invention has the characteristics that the stator punching is made of silicon steel, a stator winding is made by adopting modified high strength polyester paint to coat circular copper wires in double-layer lap wound embedding mode, and the end part of the stator winding is coated by epoxy glass fiber tapes. The invention has reasonable stator winding, good safety, skillful complete motor structure, good heat dispersion, low running noise, high intensity and safe and smooth operation.

The invention provides a method for testing partial performances of three-phase asynchronous motors, which is mainly applied to the factory test and after-maintenance test on three-phase asynchronous motors, and can also be used for the quick verification of newly designed technical schemes for motors. The method comprises the steps of utilizing the inherent no-load operation characteristic of a three-phase asynchronous motor to measure the rotation inertia of a tested motor rotor and measuring the torque, output power, efficiency and other partial parameter indexes of the motor according to the change of the corresponding instantaneous speed of the rotor in different states and the operation parameters of the motor, thereby leaving out the part of applying analog load in the prior motor test method.

An intelligent movable gas pumping station for mine belongs to the technical field of mine device, in particular relates to a movable gas pumping station for mine. The gas pumping station is characterized in that the station is provided with an intelligent monitoring substation and a softening water device (14); the intelligent monitoring substation comprises a processor (6), a pressure difference sensor (1) for mine, a pressure senor (3) for mine, a temperature sensor (4) for mine and a pipeline methane consistency sensor (5); an exploding insulating three-phase asynchronous motor (8) is connected with a water ring vacuum pump (10) through a shaft joint; the inlet of the water ring vacuum pump (10) is connected with a gas pumping pipeline (15), and the outlet of the water ring vacuum pump (10) is connected with a constant water level gas-water separating device (16). Making use of the intelligent movable gas pumping station for mine, the parameters can be displayed on site and monitored in real time, such as flow rate, consistency, temperature and negative pressure of gas; the station can be linked with the computer of the ground central station to remotely monitor and control and store each parameter in long time.

The invention provides a compact water-cooling three-phase asynchronous motor, belonging to the field of motor technology, in particular to a motor cooling system. The motor cooling system has the main technical characteristic that the cooling device adopts composite cooling of air and water; the cooling system comprises an internal circulation wind passage and a water circulation passage; a water jacket is sheathed outside the stator core of the motor and consists of an internal water jacket and an external water jacket; a water passage is arranged between the internal water jacket and the external water jacket; the water passage is a radial spiral water passage or an axial reciprocating water passage; one end of the water passage is provided with a water inlet and the other end of the water passage is provided with a water outlet; the cooling water drainage passage is arranged right below the motor and connected with the water passage; a cooling wind passage is arranged between the external water jacket and the shell of the motor; and two ends of the cooling wind passage are respectively provided with a wind inlet and a wind outlet. The motor has small volume, low production cost and good heat dissipation effect, and increases the power by more than two times compared with other motors of the same volume.

The invention provides a method for transforming a three-phase asynchronous motor into a permanent magnet motor. The method comprises the following steps that part of an iron core on the outer circumference of a rotor is cut off according to design needs, four sets of magnetic steel are attached to the outer circumference of the rotor, the clearances between the magnetic steel are coated with non-magnetic material layers, the outer sides of the magnetic steel are covered with non-magnetic metal layers, dynamic balance is detected, the transformed rotor is arranged in a stator, and the permanent magnet motor is formed.

The invention discloses a control method and device for dual three-phase asynchronous motors. The method comprises the following steps of respectively injecting a first high-frequency voltage signal and a second high-frequency voltage signal into a first set of three-phase winding and a second set of three-phase winding which are arranged on stator sides of the dual three-phase asynchronous motors so as to achieve high-frequency injection of a harmonic subspace of the dual three-phase asynchronous motors; acquiring a high-frequency current response in the harmonic subspace; processing to obtain a stator magnetic flux position angle according to the high-frequency current response; and achieving control based on directional stator magnetic flux according to the stator magnetic flux position angle, wherein the first high-frequency voltage signal and the second high-frequency voltage signal are same in amplitude and opposite in phase. With the advantages of non-ideal characteristics of the dual three-phase asynchronous motors and development of various controllable freedom degrees of the dual three-phase asynchronous motors, the running performance of the dual three-phase asynchronous motors under the working conditions of a low speed and an extremely low speed without using a speed sensor is improved.

The invention provides a low cost industry inverter system based on a TMS320F28015PZA DSP from Texas Instrument, namely, use one main control chip DSP to control two three-phase asynchronous motors at the same time. One TMS320F28015PZA DSP main control chip cooperated by the surrounding hardware circuit is used to generate 12 channels of PWM (Pulse Width Modulation) wave which can control 12 IGBT tubes, thus the circuit can generate two three-phase electric signal outputs. The low cost industry inverter system of the invention aims to use one inverter to control two three-phase asynchronous motors at the same time, thereby saving one DSP main control chip, reducing the equipment volume and effectively reducing the cost; meanwhile, the low cost industry inverter system of the invention greatly increases the reliability and stability of the control system.

The invention relates to a vortex type grinding machine which is characterized by comprising a grinding mechanism, a feeding mechanism and a sorting mechanism, wherein the grinding mechanism comprises a grinding groove fixed on a fixed disk, a rotating shaft is fixed in the middle of the grinding groove, the lower end of the rotating shaft stretches out of the fixed disk, a big belt wheel is fixed at the end of the rotating shaft, and the big belt wheel is connected with a motor belt wheel installed on the output shaft of a three-phase asynchronous motor through a belt; the feeding mechanism comprises a feeding hopper installed on a pedestal, the top of the feeding hopper is fixed on a hopper shaft, both ends of the hopper shaft are installed on the pedestal through a bearing seat, and the feeding hopper can make circular motion around the hopper shaft as the center of a circle; and the sorting mechanism comprises a vibrating body, the vibrating body comprises an upper vibrating screen body and a lower vibrating screen body, and a screen plate is arranged between the upper vibrating screen body and the lower vibrating screen body. The vortex type grinding machine has high degree of automation, reasonable structure, easiness and safety in operation, large speed change range, smooth operation, low noise, high grinding efficiency and high material utilization rate.

The invention relates to a mining flameproof threephase asynchronous motor with small volume and large power, in particular to a water cooling structure of a motor. A front end cover and a rear end cover of a motor and a motor base are respectively provided with cooling water channels; the cooling water channels of the front end cover and the rear end cover of the motor and the motor base are connected in series to form a cooling water path. The cooling water channel of the motor base comprises three parts which are respectively sealed, namely the part connected with the cooling water channel of the front end cover, the part connected with the cooling water channel of the rear end cover, and the cooling water channel part of the motor base. The invention has the advantages that as the cooling water channels of the front end cover and the rear end cover of the motor and the motor base are connected in series to form one cooling water path, the cooling structure of the motor and the cooling water supply system of coal mine machinery are simplified; under the situation that the cooling water supply system of coal mine machinery operates normally, the short-term damage to the motor bearing can be effectively avoided.

The invention relates to a wire-wound three-phase asynchronous motor with an external electric brush and an external slide ring. The motor comprises a stator core, a stator winding, a stand, a rotor core, a rotor winding and a rotary shaft; the rotor winding is correspondingly connected with a stator binding post in a stator junction box outside the stand through an outgoing line passing through a leading wire groove of the stand; the rotor winding is correspondingly connected with the slide ring fixed on the rotary shaft through an outgoing line passing through a leading wire groove of the rotary shaft; the electric brush on an electric brush frame is correspondingly and slidably contacted with the slide ring; and the shaft extension end of the rotary shaft is supported on a front end cover at one end of the stand through a bearing. The motor is characterized in that the non-shaft extension end of the rotary shaft is supported on a rear end cover at the other end of the stand through a bearing; a slide ring cover for assembling the electric brush frame covers the slide ring and the electric brush which are positioned at the outer side of the rear end cover, and is connected with the rear end cover; the electric brush is correspondingly connected with the rotor binding post in the stator junction box through an outgoing line passing through a conductor hole on the rear end cover and the leading wire groove of the stand; and a fan is installed on the non-shaft extension end, extending out of the slide ring cover, of the rotary shaft. The motor provided by the invention has the advantages of compact structure, light weight and low cost.

The invention relates to a high-voltage explosion-proof three-phase asynchronous motor. It includes a base cylinder, a front end cover, a rear end cover, a rotating shaft and a support. A high voltage junction box support and an auxiliary junction box support are arranged on the base cylinder. The inside of the matching part of the cover is respectively provided with a bearing inner cover and a matching labyrinth ring, which form a labyrinth-type flameproof joint surface structure; Flame-proof structure, its flame-proof length is 28-32mm, and the flame-proof gap is 0.05-0.07mm. The present invention has positive and beneficial effects: it can withstand the hydraulic pressure (explosion) pressure of 2.0Mpa; Chemical sites containing gases with huge explosive energy such as hydrogen and acetylene.

The present invention belongs to the field of mechanism engineering technology. The grinding wheel sharpening apparatus includes CO2 laser, fixing rack, focusing lens, belt wheel, frequency regulating motor, main shaft, grinding wheel frame, and triphase asynchronous motor. Through grinding wheel sharpening digital simulation to obtain the proportional relation between the groove depth and E1, selecting output power and light spot diameter of CO2 laser to determine the linear speed of the grinding wheel, regulating output power and light spot diameter of CO2 laser, regulating the rotation speed of the frequency regulating motor to regulate the surface linear speed of the grinding wheel, regulating the rotation speed of the triphase asynchronous motor to regulate the axial speed of the grinding wheel, and regulating performance parameters of the laser to control the sharpening effect precisely, ideal grinding wheel may be obtained.

The invention discloses a flow automatic control multifunctional coarse cereal rice mill which is applicable to half-polishing and whitening processing of various coarse cereals such as millets, proso millets, sorghums, myotonin, rice and the like. The flow automatic control multifunctional coarse cereal rice mill mainly consists of a feed hopper, a whitening chamber, a rack, a control box and a three-phase asynchronous motor; the feed hopper is fixed at the left upper part of the rack; the whitening chamber is arranged inside the rack; the control box is fixed at the right upper part of the rack; and the three-phase asynchronous motor is fixed on the ground. The feed hopper is provided with a flow automatic control device, so that the automatic control of the feeding speed is implemented; the whitening chamber can be matched with an emery roll or an iron roll for use; and the whitening chamber is also provided with a huller blade gap regulating device for regulating a gap between a huller blade and a roller. According to the invention, a control system which uses a PLC (Programmable Logic Controller) as the core is adopted; the flow automatic control multifunctional coarse cereal rice mill is suitable for milling the coarse cereals with various different shapes; the damage rate of materials is reduced; and the automation degree of equipment is improved.

The invention relates to control equipment of power electronics and aims to provide a soft starter used for continuous frequency conversion and voltage transformation of the motor. The soft starter comprises a mechanical switch K1 which is connected with a three-phase electric network power supply, and further comprises a series circuit which consists of an inverter and a fully-controlled high-frequency electronic switch Kd, wherein the series circuit and a capacitor C0 are connected to two output terminals of a three-phase diode rectifier bridge in parallel; the mechanical switch K1 is connected to an input terminal of the three-phase diode rectifier bridge; in the inverter, three pairs of bridge arms are formed by six sets of thyristors Th1,1' to Th6,6'; each pair of bridge arms consist of two anti-parallel thyristors; and the center point of an upper bridge arm and a lower bridge arm of each of the three pairs of bridge arms leads a lead out respectively and is connected to a three-phase asynchronous motor through a mechanical switch K4. In the soft starter used for continuous frequency conversion and voltage transformation of the motor, three functions of regulating voltage, switching off an inverter thyristor, and switching off the main circuit when protection is needed can be simultaneously realized by using only one fully-controlled electronic switch Kd. Simultaneously, due to the adoption of the thyristor inverter, the soft starter has the advantages of simple and reliable circuit, low cost, and great use flexibility.

An electrical practice training device comprises a power source, a controller, a sampling unit, a driving unit, a three-phase alternating-current input, a contactor, an on-off control unit, a practice training unit, a terminal strip, a practice training circuit connecting line, a communication interface, a computer and an indication element. By means of different wiring schemes, inching and self-locking control and positive and reverse rotation control of three-phase asynchronous motors can be completed, and start and stop sequence control, pole-changing speed control, remote and local control, plug braking control and dynamic braking control of the two motors are completed, so that convenience is brought to electrical practice training, and hand operation capability of students can be improved.