1487 results about "Electromagnetic torque" patented technology

The invention provides a method for injecting a harmonic voltage to restrain a harmonic current of a PMSM (permanent magnet synchronous motor), which is characterized in that a ring to restrain the harmonic current is added to realize the closed-loop control for the harmonic current on the basis of extracting harmonic current components in the PMSM in real time, thus calculating to obtain harmonic voltage components which are required to be injected to restrain 5-order and 7-order harmonic currents of the PMSM; and then the obtained harmonic voltage components are injected into a three-phase control voltage in a speed control system of the PMSM so as to offset the 5-order and 7-order harmonic components in a motor current when the PMSM runs, thereby reaching the purpose of restraining the 5-order and 7-order harmonic currents. The method is used to solve the technical difficulty that current ZCP (zero crossing point) is required to detect accurately in a traditional mode to restrain the harmonic current, remarkably improves the current waveform of the motor, effectively restrains the 5-order and 7-order harmonic currents caused by the nonlinear characteristics of an inverter and the air-gap field distortion of the motor, effectively reduces the additional loss caused by the 5-order and 7-order harmonic current components, reduces the electromagnetic torque and the revolving speed pulse of the PMSM and improves the running efficiency and the running reliability of the PMSM.

The invention discloses a direct torque control system of a permanent magnet synchronous motor based on a terminal sliding mode, which belongs to the field of motor control. The system comprises a main circuit, a signal detection circuit, a rotational-speed outer-ring controller for the terminal sliding mode, a torque linkage inner-ring controller for an adaptive fuzzy sliding mode, a stator-linkage electromagnetic torque estimation module, an SVPWM module, a 3/2 coordinate transform module, and a rotor position/speed estimation module; the design on the rotational-speed outer-ring controller is realized by using a terminal sliding mode control method based on the adaptive estimation of load disturbance, and the rotational-speed outer-ring controller outputs direct-torque controlled demand signals; and the design on the torque linkage inner-ring controller is realized by using an adaptive fuzzy sliding mode control method, and the torque linkage inner-ring controller outputs two-phase alternating voltages in a two-phase stationary coordinate system; and through carrying out SVPWM transformation on the two-phase alternating voltages, a power switching element acted on an inverter of the main circuit implements the direct torque control of the permanent magnet synchronous motor. The direct torque control system in the invention has the advantages of quick torque response speed, good robustness, small tracking error, and capability of improving the reliability and static/dynamic characteristics of the system.

The invention designs a control method of an inverter on a rotor side of a double fed wind induction generator. In the control method, a traditional PI adjustor is changed into a PIR adjustor, and a setting frequency Omega c in the PIR adjustor is set as a bisynchronous revolution angular speed Omega s, that is, a double frequency negative sequence component in disturbance quantity can be restrained completely, so the situation that power outputted to a power grid oscillates caused by impulsive motion of the electromagnetic torque of an engine because of unequal power grid voltage can be avoided. At the same time, the PIR adjustor can track a positive sequence component with frequency being zero and the double frequency negative sequence component in the forward path which are input in an astatic manner, thereby avoiding that unequal voltage aggravates the imbalance of stator current to cause a stator winding to heat because of serious imbalance. In addition, the control method realizes the control of the inverter on the rotor side of the generator under the condition of the unequal power grid voltage only through the replacement of the adjustor, the alteration thereof is simple, the effect is obvious, the design of complex elements is not involved, and the actualization is easy.

The invention discloses a coordination control method for double-fed asynchronous wind driven generator high voltage ride through, on the basis of a mathematical model of a double-fed asynchronous wind driven generator and gird side and rotor side converters of the double-fed asynchronous wind driven generator, allocation principles of active and reactive power of the grid side and rotor side converters of the double-fed wind driven generator are calculated, extremity expressions of active and reactive current are given, and a high voltage ride through implementation scheme capable of effectively providing dynamic reactive support for a power grid and eliminating direct current bus voltage, active power, reactive power and electromagnetic torque ripples is provided. The coordination control method in the invention can overcome defects of weak ride through capability and poor power grid stability of a wind driven generator in the prior art, thereby achieving the goal of optimal control of the generator when the power grid voltage is high; and the method can perfectly be implemented on the basis of original low voltage rid through hardware, thereby realizing joining with an existing low voltage ride through scheme of the unit, and forming a generalized voltage fault ride through control strategy capable of coping with a sudden change of amplitude of network voltage.

The invention discloses a permanent synchronization motor torque control method based on a sliding mode flux linkage observer. Direct torque control is performed on a permanent synchronization motor through a 3/2 coordinate conversion module, the sliding mode flux linkage observer, an electromagnetic torque calculation module, a rotating speed PI adjustor, a torque PI adjustor, a flux linkage self-adaptation module, an expected voltage calculation module, an SVPWM module and an inverter. The sliding mode flux linkage observer is adopted for estimating the size, phase and rotator speed of stator flux linkage, and set torque is processed through the flux linkage self-adaptation module to obtain a set value of the stator flux linkage. Expected voltage calculation is performed on size and phase estimation values and the set value of the stator flux linkage and the output quantity of the torque PI adjustor, so that two-phase alternating-current voltage reference values on a two-phase static coordinate system are obtained, and then through SVPWM conversion, a switching signal is obtained to drive the voltage source inverter to achieve direct torque control over the permanent synchronization motor.

The invention discloses a starting method of a brushless, position sensor- free DC motor based on current feedback. The method comprises the steps as follows: a rotor is pre-positioned; the direction changing and the current converting are carried out; a preset voltage value is calculated according to a pressure-raising curve and is output in the form of PWM; the direction changing and the current converting are carried out when detection shows that a phasing current value I exceeds a predetermined value IH, and the preset voltage value in the next step is calculated at the same time according to the pressure-raising curve; and an electric motor is switched over to closed-loop operation when the current converting frequency is greater than the predetermined value, that is, rotational speed is high enough to obtain a back-EMF signal. Based on the real-time detection on the starting current, the technical proposal of the starting method obtains better starting performance compared with a traditional three-step starting method, ensures the stability and controllability of Delta during the whole accelerating process, leads the starting current to be more stable, enables the accelerating process to be smoother, automatically reduces the rotational speed and the Delta so as to obtain greater electromagnetic torque without desynchronizing when meeting with load disturbance, and does not need to add extra hardware or timers, thereby being simpler and more reliable.

The invention relates to a low-voltage traversing control method for a double-fed wind power generation system, which belongs to the technical field of wind power generation. The method comprises the following steps: firstly, the stator flux and the rotor flux of a double-fed generator are calculated according to the stator current and the rotor current of the double-fed generator which are measured by a current sensor; secondly, the stator flux is multiplied by a corresponding proportionality factor to serve as the set value of the rotor flux of the double-fed generator, so as to control therotor flux; and thirdly, the rotor flux is controlled in the way that as feedforward compensation decoupling is performed, closed-loop control is conducted to the decoupled system, and a rotor-side converter is controlled after pulse-width modulation is conducted to the obtained voltage control quantity of a rotor-side converter, so as to achieve low-voltage traversing control during failures. The low-voltage traversing control method provided by the invention has fast response, and very good traversing effect when symmetrical and asymmetrical drop failures of the network voltage occur, meanwhile, and oscillation of output electromagnetic torque of the double-fed generator can be effectively inhibited. The control method is simple and suitable for engineering application.

The invention relates to a method for suppressing the torque ripple of a permanent-magnet motor based on space vector modulation. The method comprises the following steps of: adopting a vector control strategy that a permanent-magnet motor has a zero direct axis current so that electromagnetic torque and a quadrature axis armature current form a linear connection; and solving an additional quadrature axis injection harmonic current according to the linear connection of the electromagnetic torque of the permanent-magnet motor and the quadrature axis armature current so that an additional electromagnetic torque high-harmonic component generated by coupling the quadrature axis injection harmonic current and the direct axis permanent-magnet chain and fundamental and high-harmonic components in the orientation torque of the permanent-magnet motor have identical amplitude and opposite phases and can be mutually counteracted to suppress the torque ripple. The invention adopts the permanent-magnet motor as an implementation object, and the motor of the type can adopt advanced control protocols of vector control, direct torque control, and the like so that the method is simple and practical by editing control software without increasing the hardware cost of a control system and can obviously suppress the torque ripple of the motor and remain the constant motor characteristics of idling magnetic potential, torque output capability, and the like.

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 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 a brushless direct current motor electromagnetic torque observation method based on a self-adapting slip-form observer, belonging to the control field of permanent magnet motors. The observation method comprises the following steps of: constructing a state space equation of a brushless direct current motor in an alpha-beta coordinate system based on easily-observing signals, such as motor rotating speed, each phase current of a stator, each ground voltage of the stator, rotor position, and the like; observing a counter emf (Electromotive Force) of the brushless direct current motor in the alpha-beta coordinate system in real time by using the slip-form observer; meanwhile online identifying a stator resistance parameter of the brushless direct current motor to eliminate the influence of a resistance parameter error on counter emf observation; and finally calculating the electromagnetic torque of the brushless direct current motor in real time according to the counter emf, the current and the rotating speed. In the invention, when the stator resistance parameter is unknown or a stator resistance changes due to the influences of temperature and skin effect, the counter emf and the electromagnetic torque of the brushless direct current motor can be accurately observed, the problem of the traditional method influenced by the resistance parameter is solved, and an accurate torque feedback value can be provided for the torque close loop control of the brushless direct current motor.

The invention discloses a permanent-magnet synchronous motor torque control system and method based on sliding-mode observer and auto-disturbance rejection control, so that the torque of the permanent-magnet synchronous motor is controlled rapidly and precisely. A minimal-order extended flux-linkage sliding-mode observer is designed; an auto-disturbance rejection current controller is designed; difference processing is carried out on an electromagnetic torque outputted by an observer and a given torque signal outputted by an upper computer and the difference is inputted into a PI controller; a q-axis current signal outputted by the PI controller and dq-axis flux-linkage component outputted by the observer are inputted into the auto-disturbance rejection current controller to form a torque closed loop. According to the permanent-magnet synchronous motor torque control system and method, the dynamic response of the output torque of the motor is accelerated and no overshoot phenomenon is avoided. Moreover, on the basis of combination of the sliding-mode observer and the auto-disturbance rejection controller, the reliability and robustness of the torque control of the permanent-magnet synchronous motor are enhanced. The permanent-magnet synchronous motor torque control system and method are applied to occasions with the permanent-magnet synchronous motor as a driving system.

An apparatus for measuring non contact type bearing start friction torque, is composed mainly of a loading cylinder (1), a force transducer (2), a loading housing (3), an air main shaft (5), an air bearing (6), a torque generator (7), a disk drive (8), an optoelectric transducer (9), an electrical system. The torque generator generates induction electromagnetic torque as drive torque, the optoelectric transducer monitors bearing start running state automatically; when being measured, the measured bearing is installed on the air main shaft, the disk drive is linked with the air main shaft and placed in the torque generator, the electrical system applies input power to the torque generator step by step after throwing axial load, when the induction electromagnetism drives the air main shaft to rotate through the disk drive, the optoelectric transducer matching-installed by the disk drive monitors the measured bearing from static state to start running state, and outputs signal to stop applying input power, and records current power value which is the start friction torque value of the measured bearing.

The invention provides a wind energy converting system sliding mode control method and device based on a T-S fuzzy model. To solve the problem of the fault of an actuator in a wind energy converting system, the T-S fuzzy model is utilized for describing a nonlinear wind energy converting system with uncertain actuator fault information, the approximation accuracy of a controlled object is improved, and a good model foundation is established for sliding mode control. Meanwhile, by means of a sliding mode controller designed based on the linear matrix inequality technology, the stability of the wind energy converting system is guaranteed, and the robustness and fault tolerance of the wind energy converting system are improved. The precise tracking of the rotating speed of a power generator and the electromagnetic torque can be achieved when the uncertain actuator fault exists in the wind energy converting system, and the maximum wind energy capturing of the wind speed below the rated value is achieved, and a valuable reference scheme is provided for efficient and stable running of the wind converting system.

The invention provides an electromagnetic formation satellite attitude and track relative control method. The method comprises the following steps: 1, attitude dynamics equations are built; 2, according to the attitude dynamics equation in a linear form with quaternion representation built in the first step, an attitude dynamics equation in a body coordinate system and a rigid satellite dynamics equation, a satellite attitude control system feedback control law is designed and obtained; and 3, according to the feedback control law obtained in the second step, relative control is carried out on the electromagnetic formation satellite attitude and the track. The method of the invention has the advantages that the attitude dynamics equations, a relative motion dynamics equation and electromagnetic force and electromagnetic torque models are built, the designed satellite attitude control system feedback control law, a flywheel angular momentum magnetic unloading algorithm, a large angle attitude maneuver method, an electromagnetic formation flying satellite motion controller and a magnetic dipole control distribution method can have good working performance, and high-efficiency relative control on the electromagnetic formation satellite attitude and the track can be realized.

The invention discloses a permanent magnet synchronous motor torque control strategy based on a flux linkage vector. According to the strategy, on the basis of finite set model prediction control, through analyzing internal relations between an electromagnetic torque reference value, a stator flux linkage reference value and a flux linkage vector phase angle, the electromagnetic torque reference value and the stator flux linkage reference value are converted into a flux linkage vector reference value, and a value function based on a flux linkage vector error is constructed. According to the strategy, the value function is utilized to evaluate action effects of alternative voltage vectors of a control set, switch frequency reduction for loss reduction is realized, a finite control set mode is employed, an optimum duty ratio of each alternative voltage vector is acquired through calculation when the value function is made to be smallest, the optimum duty ratio is further utilized, and the torque control strategy based on the flux linkage vector is realized.

The invention provides a wind turbine generator control method, a controller and a control system of wind turbine generator. The method comprises the steps of acquiring the air velocity in front a hub by a distance two to three times the diameter of an impeller, the pitch angle of the impeller at the current moment as well as the rotation angular speed of the generator, calculating the pneumatic torque of the impeller, and calculating corresponding electromagnetic torque; acquiring the current torque given value and a pitch angle given value; and correcting the given value outputted by a torque controller or a variable-pitch controller. The controller comprises a pneumatic torque calculation module, a torque controller, a variable-pitch controller and a controller given value correcting module. The control system comprises a laser radar wind speed measurement instrument, a wind turbine generator, and the above controller. The wind turbine generator control system provided by the invention can respond to the wind speed change in advance to correct the variable-pitch and torque control effect so as to improve the wind energy utilization rate of the wind turbine generator, thereby obviating integral fatigue loads and power generation loss caused by impeller inertia and delay of the pitch-variable system.

The invention relates to a control device for a brushless direct current motor sensorless based on 12-beat control and a method thereof. The device comprises a direct current power supply, a three-phase inverter, a brushless direct current motor, a drive circuit of a power device of the three-phase inverter, a microcontroller and a rotor position detection circuit, wherein the direct current power supply is connected with the brushless direct current motor through the three-phase inverter; after the rotor position detection circuit is connected with the brushless direct current motor for detecting, an output signal is directly connected with an analog-to-digital conversion input pin of the microcontroller; and six-path output of the microcontroller is connected to the three-phase inverter through the drive circuit of the power device of the three-phase inverter. The method detects terminal voltage of an inactive phase winding in a two-pipe conducting region at PWM conducted moment by an analog-to-digital conversion unit embedded in an XC866 singlechip, and acquires back electromotive force zero crossing as accordance of 12-beat phase conversion, thereby reducing the requirement of the adopted control device of the brushless direct current motor sensorless on a peripheral circuit, and achieving the aims of not only effectively inhibiting electromagnetic torque pulsation, but also reducing the system cost.