748 results about "Stator voltage" patented technology

The invention relates to a current predictive control method of a permanent magnet synchronous motor, which belongs to the electric control field. The dynamic response speed and the control accuracy for the stator current control of the permanent magnet synchronous motor are improved through stator current prediction and deadbeat control, and the system delaying is compensated, so that the noise and the torque ripple of the motor in operation are reduced. The method comprises the steps as follows: obtaining a three phase stator current signal, and the electrical angle and the electrical angular speed of the motor rotor through the technologies of sensor sampling and a photoelectric coded disc or position sensorless detection; carrying out Clarke transformation and Park transformation on the stator current signal to obtain the stator current in a synchronous revolution dq coordinate system; substituting the obtained stator current signal in the dq coordinate system into a control equation of a current predictive controller of the permanent magnet synchronous motor, carrying out deadbeat control according to the given value of the obtained stator current in the dq coordinate system in an outer ring controller to obtain a stator voltage vector in the dq coordinate system; carrying out Park inverse transformation on the obtained stator voltage vector in the dq coordinate system, to obtain a pulse-width modulation (PWM) control signal of an inverter by a space vector pulse width modulation (SVPWM) method, controlling the stator current through the inverter, and then implementing the current predictive control over the permanent magnet synchronous motor.

The invention relates to a online testing process for shorted fault of asynchronous motor's stator winding, which is belong to Detecting Technology. It was designed to solve the detecting problem of stator winding. The project is that it figures out the voltage and current of negative sequence and positive sequence of the stator winding by collecting three-phase stator voltage, instantaneous-current signal. Then using of normal motor sample reference document estimated the filter value of the stator negative sequence, figured out the stator negative sequence current fault component. And then base on the threshold of the stator negative sequence current fault component educe failure exponent. Finally according to the index judge whether to exist short circuit failure or not. This invention also gave corresponding detection device. Not only can high sensitivity, high reliability and on-line measurement asynchronous motor stator windings at the beginning of the early short circuit fault, but also can judge short circuit phase. This can effectively ensure the asynchronous motor operating safely.

A brushless generator with permanent-magnet multi-pole rotor disks and stator winding disks in their axial magnetic field includes integral electronics to efficiently generate regulated DC current and voltage from mechanical input power over a broad speed range. All power for the electronics is provided by rectifier diodes from its stator windings. Differential amplifiers provide stator voltage feedback signals. Its power rating is scalable, depending on the number of its disks. Having no iron cores and no gears, it incurs no cogging torque, and no gear friction. Integral power control electronics includes high-frequency pulse-width-modulated boost regulation, which provides regulated current at requisite voltage over its broad speed range. A main wind-powered embodiment to produce DC power for a constant voltage DC load over a broad speed range includes signal processing so output power varies according to the third power of speed. Combined boost-regulation, zero cogging torque, and no gearing, enable a wide speed range, for better power quality and higher wind energy yields.

The invention relates to the technical field of electric transmission and control, in particular to a speed sensor-less method for estimating the rotor angle and the revolving speed of a permanent-magnet synchronous motor. The method comprises the following steps: a. obtaining the rotor flux linkage amplitude Psi<r> of a permanent-magnet synchronous motor; b. transforming a stator voltage fundamental component to be under an alpha beta coordinate system to obtain u<alpha> and u<beta>; c. transforming the stator current fundamental component to be under the alpha beta coordinate system to obtain i<alpha> and i<beta>; d. carrying out highpass filtering on stator current i<alpha> and i<beta> under the alpha beta coordinate system, and obtaining the differential estimation value sum of the stator current; e. obtaining a stator counter electromotive force estimation value; f. obtaining a rotor revolving speed calculation value omega<rC> and a rotor angle calculation value theta<rC>; g. carrying out lowpass filtering on the rotor revolving speed calculation value omega<rC> to obtain a rotor revolving speed estimation value; h. obtaining the estimation value of a rotor angle starting value; and i. obtaining a rotor angle estimation value. The method has the advantages that only forward calculation, instead of a feedback channel, exists in the method for estimating the rotor angle and revolving speed, and except filter delaying, no dynamic regulation process exists.

To shorten a startup interval to reach a synchronizing condition, a phase difference and an amplitude difference between the grid voltage and the stator voltage of one phase of a winding are obtained. The difference in amplitude is decreased prior to or in parallel to synchronizing the stator voltage with the grid voltage. The calculated compensation phase compensation value is used as an initial value for synchronizing at the next synchronizing operation.

The invention discloses a control method of an open winding permanent magnet synchronous motor system of a hybrid inverter. The control method comprises the following steps: after acquiring voltage and current of a three-phase stator of a motor, performing three-phase/two-phase static coordinate transformation to obtain voltage and current under a two-phase static coordinate system, thereby obtaining actual feedback values of electromagnetic torque and stator flux linkage; obtaining an initial given value of the electromagnetic torque through a PI (Proportional Integral) controller so as to obtain given values of the electromagnetic torque and the stator flux linkage; then combining output of a capacitor voltage PI controller to obtain final given voltage vectors of two inverters; finally generating a switching signal of the inverters through space vector pulse width modulation; and triggering a switching device of the hybrid inverter to realize direct torque control of the open winding permanent magnet synchronous motor. According to the control method, wide-range operation of low, medium and high speed of the open winding permanent magnet synchronous motor is realized, the electromagnetic torque in a motor acceleration process is increased, the voltage utilization rate of a direct current voltage source is improved, and high-speed constant-power operation of the permanent magnet synchronous motor is guaranteed.

The invention provides a judgment method of a key sensor fault of a double-fed wind generating set, which realizes effective judgment of the key sensor fault by utilizing observer models, a fault detection unit and a disturbance filer unit. The judgment method comprises the following steps: constructing the observer model of stator current and rotor current and the observer model of stator voltage starting from an electromagnetic transient model of a double-fed generator; constructing the fault detection unit by an adaptive threshold method through analysis on the possible soft and hard fault types of the sensor; When the fault residual error is greater than an adaptive threshold value, constructing the disturbance filer unit by design of a timing unit; and finally completing design of the judgment models of the sensor fault based on the adaptive threshold value. The judgment method adopts an algorithm for constructing corresponding observers so as to improve the adaptability and the accuracy of the observer algorithm on fault judgment; and by combination of the adaptive threshold value and the disturbance filer unit, the false alarm rate of the sensor fault is reduced and the robustness of fault judgment is improved.

The invention belongs to the field of control over a power conversion device for a wind driven generator and relates to a method for controlling current switching of a double-feed wind driven generator rotor under an imbalanced power grid voltage. The method comprises the following steps of: calculating a stator voltage, a stator current and a rotor current under a two-phase static coordinate system; calculating stator voltages and stator currents of a d axis and a q axis under a flux linkage and a synchronous rotation coordinate system; calculating a slip angle and a slip angular velocity; calculating rotor currents of the d axis and the q axis under the rotation coordinate system; calculating stator active power, reactive power and electromagnetic torque; calculating rotor decoupling compensating voltage; naturalizing and calculating corresponding control variables, acquiring a secondary pulse actual value of a controlled variable through a bandpass filter and a lead lag link, subtracting the actual value from a secondary pulse given value, and calculating to acquire a two-time frequency compensation item through a proportional integral (PI) controller; calculating the given value of the rotor current of the d axis under the rotation coordinate system; allowing the difference of a rotation speed given value and a rotational angular velocity actual value to pass through the PI controller, and calculating to acquire the given value of the rotor current of the q axis under the rotation coordinate system; calculating to acquire reference values of rotor voltages of the d axis and the q axis under the rotation coordinate system; and calculating the rotor voltage under the rotor two-phase static coordinate system and generating switch signals which control power devices.

The invention discloses an open-loop control method and an open-loop control system of a permanent magnet synchronous motor based on space vector pulse width modulation (SVPWM). To each given stator power frequency, the amplitude of stator voltage corresponding to the given stator power frequency is found through searching a two-dimensional vector table of the stator voltage and the stator power frequency, wherein the two-dimensional vector table is set according to a sectional voltage/frequency ratio curve in advance, that is to say, the ratio of the stator voltage and the stator power frequency in the two-dimensional vector table disclosed by the invention is not a normal value; and the ratio is different in different interval sections. In the prior art, as the voltage/frequency ratio is a normal value, when a load changes, a motor is out of step easily so as to cause overcurrent to the system. In the method disclosed by the invention, the sectional voltage/frequency ratio can guarantee the motor to adapt to the change of the load, reduce the consumption of the motor and improve the efficiency. In a constant power area, phase compensation is introduced, so that weak magnetic control is realized by using the regulated phase, and weak magnetic speed improvement is realized.

The invention discloses a current prediction control method and apparatus for a permanent magnet synchronous motor (PMSM). The method comprises the steps: acquiring the motor stator current and stator voltage under two-phase rotating coordinates; constructing a current and perturbation sliding-mode observer, and predicting and obtaining the motor stator current and the parameter perturbation estimated value of the next moment; according to the principle that the practical current value of the next moment is equal to a current command value, obtaining a PMSM current prediction control expression; taking the current value, predicted by the observer, of the next beat, as current feedback, and obtaining the command voltage of a motor driver through calculation; and further adding the command voltage and the parameter perturbation estimated by the observer together, taking the sum as the final motor driver command voltage, and finally generating a pulse signal for controlling motion of a switch tube through an SVPWM device. The current prediction control method for a permanent magnet synchronous motor can predict the current of the next beat and estimate parameter perturbation at the same time, and can effectively restrain the current tracking static error and reduce the motor harmonic wave current and optimize the current control performance when a parameter mismatching problem exists.

The invention discloses a method for controlling direct torsion/ flux linkage of a permanent magnet synchronous motor. The method comprises the steps of collecting three-phase stator voltage and currents of the motor, and obtaining voltage and currents under a two-phase static coordinate system through three-phase/two-phase static coordinate conversion; calculating actual feedback value of electromagnetism torsion and stator flux linkage according to the voltage and the currents under the two-phase static coordinate system; obtaining initial given value of the electromagnetism torsion through a PI controller according to difference between given rotating speed and feedback rotating speed; obtaining given value of the electromagnetism torsion and the stator flux linkage according to a given electromagnetism torsion and stator flux linkage calculating module; obtaining given voltage on an alpha beta shaft of the two-phase static coordinate system through a given voltage calculating module; generating switching signals of an inverter through space vector pulse width modulation, triggering a switching device of the inverter, and realizing direct torsion/flux linkage control of the permanent magnet synchronous motor. The method realizes low, medium and high speed wide range operation of the permanent magnet synchronous motor, does not need to rotate coordinate conversion, and has the advantages of being convenient to calculate, quick in dynamic response, strong in robustness, and the like.

A permanent magnet synchronous motor sliding-mode speed observer driven by a two-stage matrix converter comprises a motor model based on the sliding-mode observer, an S-shaped switch function, an angle calculation module and an angular speed calculation module. Ualpha and Ubeta, obtained through the voltage reconstitution method, of stator voltages in a two-phase static coordinate system of a permanent magnet synchronous motor and the two S-shaped switch function output values (see the specification) serve as the motor model input based on the sliding-mode observer, the stator actual current values including ialpha and ibeta are subtracted from the four motor model output stator current observing values (see the specification) based on the sliding-mode speed observer, the two difference values serve as the S-shaped switch function input, the difference values are processed through the permanent magnet synchronous motor sliding-mode speed observer, then the two counter EMF estimated values in the two-phase static coordinate system are output, the rotor position is obtained through the angle calculation module, and the angular speed is obtained through the angular speed calculation module.

A method for sensorless estimation of rotor speed and position of a permanent magnet synchronous machine the method comprising the steps of calculating first stator flux vector estimate ({circumflex over (ψ)}_d,i+j{circumflex over (ψ)}_q,i) using the flux model and measured stator currents, calculating second stator flux vector estimate ({circumflex over (ψ)}_d,u+j{circumflex over (ψ)}_q,u) using the voltage model and measured stator voltages, comparing the directions of the first and second flux vectors to achieve a first error signal (F_ε), using speed adaptation to achieve estimates for the rotor angular speed ({circumflex over (ω)}_m) and angular position ({circumflex over (θ)}_m) from the first error signal (F_ε), injecting a known voltage signal (u_c) to the stator voltage, detecting a current signal (i_qc) from the stator current to form a second error (ε) signal, which is dependent on the estimation error of the rotor position, augmenting the voltage model by the second error signal (ε) to keep the first and second flux vector estimates aligned and so to correct the rotor angular speed ({circumflex over (ω)}_m) and angular position ({circumflex over (θ)}_m) estimates.

The invention discloses a voltage control type virtual synchronizing method of a double-feed wind power generator set. Through simulating inertia and a frequency-modulating and voltage-modulating characteristic of a synchronizer, the set can be different from a characteristic of no electric grid frequency change response in a traditional current control type, thereby possessing capability of supporting voltage and frequency of a weak power grid based on the voltage control type through virtual inertia. The method provides and realizes a VCT-DFIC virtual synchronous control structure of which an inner ring is controlled by an improved double-feed generator stator voltage rotor current double-closed-loop structure based on adaptive stator virtual impedance and transmission line sag voltage feedforward compensation in a control manner which includes crossed control between stator voltage and rotor current and furthermore an outer ring is controlled by a virtual synchronous realizing algorithm. The method realizes output power control in VCT-DFIG grid integration operation in a weak grid condition with any actual impedance and effective decoupling, and furthermore a designed control structure realizes higher inertia and frequency supporting capability of the double-feed generator.

The invention discloses a permanent magnet synchronous motor state estimation method based on a sliding mode back EMF observer. According to stator voltage and stator current detected in real time, a sigmoid function is used to substitute a sign function, and the sliding mode back EMF observer is constructed to estimate the back EMF. The type of the sliding mode back EMF observer is characterized in that the observer is insensitive to switch noise and has a filtering characteristic, thus the filtering of the estimated back EMF through a low-pass filter is not needed. After the normalization processing of the back EMF, a rotor position and speed information are extracted through a PI-I structure phase-locked loop position observer equivalent to a simplified Kalman filter. The permanent magnet synchronous motor state estimation method of the invention has good estimation performance even in the condition of noise and motor parameter changes, the chattering phenomenon in a traditional sliding mode observer is reduced, and the dynamic tracking performance and estimation precision of the rotor position and speed are improved.

The invention discloses a method for asynchronous motor rotor flux linkage observation and rotation speed identification, which comprises the following steps of: according to stator voltage and current signals measured in real time, observing to obtain a rotor flux linkage through a sliding mode observer based on a super-twisting theory and using the rotor flux linkage as a reference value; using a rotor flux linkage calculated according to a rotor flux linkage current model as an adjustable value; constructing a model reference self-adaptive system (MRAS) based on the rotor flux linkages; and identifying the asynchronous motor rotation speed through the self-adaptive law. The rotation speed identification method provided by the invention has high robustness for the variation of stator resistance, and can provide accurate rotor flux linkages and rotation speed values, thereby being especially suitable for an asynchronous motor vector control system.

The invention relates to an alternating-current asynchronous motor frequency converter without a speed sensor. In the frequency converter, a personal computer (PC)-based frequency converter online debugging and monitoring software, a communication mechanism, parameter identification of an alternating-current asynchronous motor, and alternating-current asynchronous motor rotating speed identification are involved, wherein the PC-based frequency converter online debugging and monitoring software can set related parameters of the frequency converter, distribute a control command, dynamically display the related parameters of the frequency converter and an alternating-current asynchronous motor in a literary form, and dynamically display the waveforms of a rotating speed, a torque, a stator voltage and a stator current of the alternating-current asynchronous motor in a graphical form; the communication mechanism is on the basis of any one serial bus of Ethernet/a universal serial bus (UBS)/a recommend standard 485 (RS485)/a recommend standard 232 (RS232) and realizes bidirectional data communication between the debugging software and the frequency converter; the parameter identification of the alternating-current asynchronous motor comprises stator resistance, rotor resistance, stator leakage inductance, rotor leakage inductance, stator and rotor mutual inductance and total leakage inductance; and the alternating-current asynchronous motor rotating speed identification is on the basis of a model reference adaptive theory.