75 results about "Direct torque control system" patented technology

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 relates to a direct torque control system of a permanent-magnet synchronous motor. According to the control system, an extended kalman filter (EKF) observer is adopted for stator magnetic linkage and rotation speed estimation, according to a mathematical model of the permanent-magnet synchronous motor, the state variable x of the system equals to [Psi alpha, Psi beta, Omega gamma, Theta gamma] T, the input variable mu equals to [mu alpha, mu beta] T, the output variable y equals to [Iota alpha, Iota beta ] T, and state equations and output equations (11) of the system are obtained. The motor rotating speed is used as the input of an automatic data rate changer (ADRC) speed controller, the measurement value Te of the electromagnetic torque is calculated through the obtained stator magnetic linkage, in addition, the measurement value Te and electromagnetic torque given signals are compared, comparison results are used as the input of a space voltage vector pulse generator, and the output of the space voltage vector pulse generator is connected with a voltage source inverter of the permanent-magnet synchronous motor. The direct torque control system has the advantages of good dynamic performance, better stability performance, high robustness and high anti-interference capability.

In order to get rid of the direct torque control system bigger pulse torque issue, it invents an electric power driven assistant steering system based on intelligence control, introducing fuzzy neural network into the electric driven torque control, not relying on the controlled precision model, with the established fuzzy strategy being able to get rid of the nonlinear strong coupling defects of the fuzzy strategy, with better self learning, parameter automatic control and adjustment, improved system self adaptation abilities. The controller is made of MCU, PWM, and the power source module, with torque, velocity, and driven locomotive feedback current as the input language variable, through offline model construction, it forms control strategy and on line control, realizing electric assisted steering intelligent control. It applies to sedans, fuel cars, locomotives, with agile and light weight, greatly improved in operation comfort and stability.

The invention discloses a direct torque control method for a non-salient pole type hybrid excitation motor for an electric vehicle. According to the method, on the basis of a partition control strategy for the hybrid excitation motor, set values of a stator magnetic chain and excitation current are calculated by a maximum torque current ratio algorithm in different running regions; a switch table is inquired according to the set value of the torque, the set value of the magnetic chain and difference values of respective feedback values to select a voltage vector, thus a switching state of a PWM (pulse width modulation) inverter is controlled and the direct torque control over the hybrid excitation motor is realized. According to the direct torque control method, on the premise of guaranteeing the basic running characteristic of the hybrid excitation motor, the direct torque control over the hybrid excitation motor is realized, the control system algorithm is simplified, and the torque response speed of the motor is increased. Compared with the conventional direct torque control method, the method has the advantages that in different running regions, the set value of the stator magnetic chain is calculated according to the maximum torque current ratio algorithm, the reactive component of armature current is reduced, and the efficiency of the motor and the torque output capacity are improved.

The invention relates to a dead-beat direct torque control method based on permanent magnet flux linkage sliding mode identification and belongs to the technical field of control of permanent magnet synchronous motors. The dead-beat direct torque control method comprises the following steps: substituting obtained motor rotating speed, a position angle and dq axis current into a sliding mode disturbance observer and observing a voltage error; compensating a control system by utilizing an observed value and identifying permanent magnet flux linkage; calculating electromagnetic torque and statorflux linkage of a permanent magnet synchronous motor according to an identification value as feedback values of the control system; substituting reference electromagnetic torque, reference stator fluxlinkage, the feedback electromagnetic torque, the feedback stator flux linkage, the dq axis current, the motor rotating speed and motor parameters into a reference voltage vector calculation formula,adding a calculation result and a compensation value to obtain a compensated reference voltage vector; modulating a corresponding switching signal to act on an inverter. The dead-beat direct torque control method provided by the invention has the advantages that the influence of permanent magnet flux linkage parameters on the calculation of the reference voltage vector is reduced, and the systemcontrol accuracy is improved.

The invention discloses a brushless direct current motor direct torque control system and control method, the system includes a photoelectric encoder, a stator current and terminal voltage detection circuit, a speed calculator, a speed error comparator, a speed regulator, and a flux linkage observer , Flux linkage error comparator, flux linkage hysteresis comparator, torque observer, torque error comparator, torque hysteresis comparator, PWM controller and three-phase bridge inverter circuit. The photoelectric encoder collects the position information of the motor rotor, calculates the actual speed according to the rotor position information, calculates the given value of the stator flux linkage according to the rotor position information and the reference torque, and collects the three-phase current and terminal voltage of the stator to calculate the actual electromagnetic torque And the actual stator flux, the PWM controller generates a voltage vector according to the torque error and the flux error, and drives the inverter circuit through the voltage vector to realize the stable operation of the motor. The invention does not need to calculate the flux linkage in real time, simplifies the system program, and improves the control efficiency.

The invention relates to an energy-saving frequency converter of an induction motor direct torque control speed regulating system. The energy-saving frequency converter is characterized in that stator copper loss, iron core loss, total loss and motor total loss of an induction motor can be obtained according to an inductance motor approximately equivalent circuit model in a stator magnetic field orientation d-q coordinate system, and a stator flux linkage calculation module is structured and placed in a direct torque control system to form an inductance motor energy-saving variable-frequency controller which is combined with a power converter to jointly form an inductance motor energy-saving frequency converter. Control inverter switch signals output by a switch logic meter in the inductance motor energy-saving frequency converter are accessed to an input end of switch signals in a three-phase IGBT (insulated gate bipolar transistor) inverter in the power converter. The energy-saving frequency converter of the induction motor direct torque control speed regulating system has the advantage of capability of obviously reducing power loss of motor operation and improving integral comprehensive performance of a motor driving system, simple structure, reliability in operation, low realization cost and especial suitableness for application occasions in light-loaded running state frequently or with frequently changing load.

The invention provides a torque ripple suppression method of a brushless direct current motor. The torque ripple suppression method is used for performing direct torque control of the brushless direct current motor which is combined with discrete type space voltage vector modulation. The torque ripple suppression method comprises the following steps of step 1, detecting counter electromotive force of the brushless direct current motor; step 2, establishing a composite state of an inverter switch and a direct torque control sector system; and step 3, establishing selection of basic voltage space vectors in a system sector to achieve torque ripple suppression. The torque ripple suppression method of the brushless direct current motor has the advantages of being rapid in dynamic response, enabling a structure to be simple, having good suppression effect on torque ripple, greatly improving the performance of the direct torque control of the brushless direct current motor and broadening the applications.

The invention provides a direct torque control method of a PMSM (Permanent Magnet Synchronous Motor). According to the method, LSSVM is used for optimizing an ADRC speed regulator in a PMSM direct torque control system. The method comprises the following steps: utilizing a tracking value Z1 of a motor actual rotation speed wr output by an ESO in the ADRC as an input signal of an LSSVM optimal regression model obtained by disperse training, utilizing the sum of partial system disturbed value estimated by the LSSVM optimal regression model according to Z1 and other disturbed values estimated by the ESO as the system total disturbance; performing feed-forward compensation on the system total disturbance by virtue of follow-up operation of the ADRC. The invention provides a PMSM direct torque control method based on an optimization and ADRC (Auto Disturbance Rejection Controller) of a least square support vector machine. The method can be used for improving the observation precision of the ADRC and the dynamic response speed of the system, reducing the influence of the motor parameter change and load disturbance on the system, and further improving the anti-disturbance capacity of the system.

[Problem] An object of the present invention is to provide an electric power steering apparatus capable of smoothly switching the control systems without self-steer by gradually changing a control torque of the torque control and a command value of the position / speed control upon fade processing that switches the control systems.[Means for Solving the Problem] The present invention is the electric power steering apparatus including a torque sensor to detect a steering torque and a motor control unit to control a motor that applies an assist torque to a steering system of a vehicle, comprising: a function to switch a control system of the motor between a torque control system of a torque system to control a motor output torque and a position / speed control system of a steering angle system to control a steering angle of a steering in accordance with a predetermined switching trigger, wherein each of a steering angle command value and a steering angle speed of the position / speed control system and an assist torque level of the torque control system gradually change sensitive to the steering torque, when shifting from the torque control system to the position / speed control system or vice versa.

The invention discloses a direct torque control system and a method for dual-redundancy permanent-magnet fault-tolerant motors. The system comprises two direct torque control systems which are same in structure and correspond to the permanent-magnet fault-tolerant motors respectively, wherein any direct torque control system comprises an input unit, a storage unit, a detection unit, a DSP (Digital Signal Processor) and an inverter control unit; the detection units comprise voltage detection modules, current detection modules and encoders; and the DSPs comprise coordinate transformation units, flux linkage computing units, torque computing units, comparing units, PI (Proportional-Integral) regulating units, fault predication units, communication units, torque distribution units, torque hysteresis control units, flux linkage hysteresis control units and voltage vector determination units. According to the system and the method, a dual-redundancy technique and a fault-tolerant technique are sufficiently combined, so that the reliability of the system is improved, and rich voltage space vectors of the permanent-magnet fault-tolerant motors are effectively utilized.

The invention discloses a hybrid excitation synchronous motor sensorless direct torque control method. A sliding film observer is used for estimating the rotating speed and the initial position of a hybrid excitation synchronous motor, and the general control idea is based on the direct torque control method. The motor operation area is judged according to the rotating speed, the motor runs in a low-speed area, id=0 is adopted for control, and when the load torque is smaller than or equal to the rated torque, magnetism increasing control is not needed; when the load torque is larger than the rated torque, magnetism increasing control is conducted. When the motor runs in a high-speed area, magnetism weakening control is adopted, id=0 is kept firstly, magnetism weakening is conducted through excitation current if, and when the magnetism weakening if reaches the rated value, the d-axis current id is used for magnetism weakening. According to the hybrid excitation synchronous motor sensorless direct torque control method, cost is reduced, and the reliability and the fast torque responding capability of a driving system are improved.

The invention discloses an EKF-based rotating speed control method of a sensorless ultra-high speed permanent magnet synchronous motor. The method comprises the following steps of building a mathematical model of the motor and converting the mathematical model into a state equation; carrying out linearization and discretization, substituting the discrete linear state equation into an extended Kalman filter (EKF) for recursive computation, updating a variance matrix P and a gain K in the EKF in real time to update a state variable; and finally estimating the rotating speed of the motor in the dynamic operation process in real time. The rotating speed estimation method is applied to an SVPWM-based ultra-high speed motor direct torque control system; the adaptivity of the system is improved by a fuzzy PID controller; and fast, stable and reliable rotating speed control on the ultra-high speed permanent magnet synchronous motor is effectively achieved.

The invention provides a direct torque control method of high load capacity of a five-phase permanent magnetic synchronous motor, and aims to a five-phase symmetrical winding permanent magnetic synchronous motor. Stator windings are connected into a star shape; counter electromotive force of the stator windings of the five-phase permanent magnetic synchronous motor contains a high proportion of third harmonic; the voltage vector is outputted by a five-phase inverter; at the same time, a direct control strategy of a double electromagnetic toque and a stator flux linage is structured in a fundamental harmonic plane and a third harmonic plane; and simultaneously, a maximum torque algorithm of each ampere is structured by using a salient-pole phenomenon of the motor, so as to continuously refresh the amplitude value of the stator flux linage on the two planes. The control method reduces the current peak of the stator winding, structures the maximum torque control algorithm of each ampere of the salient-pole type five-phase permanent magnetic synchronous motor, and utilizes the maximum torque control algorithm to update the amplitude value of the stator flux linage on the fundamental harmonic plane and the third harmonic plane; further, the load capability of the motor is enhanced; and the current of the stator winding is reduced.

The invention discloses a direct torque control system and method for a transverse flux switched reluctance motor. The method is used for reducing torque pulsation during operation of the transverse flux switched reluctance motor, and comprises the following steps: firstly, a position detection module detects position information theta, a current detection module detects current i, and a speed calculation module calculates actual rotating speed omega r through the position information theta; a torque estimation module and a flux linkage estimation module calculate actual torque T of each phaseaccording to the theta and i, and obtain switching signals through flux linkage coordinate transformation, vector calculation, sector judgment, a hysteresis comparator and a vector switch table; andfinally, a power converter controls the transverse flux switched reluctance motor according to the switching signals.

The invention discloses a vector control AC frequency-variable speed regulation system of an electric automobile, which comprises a DSP controller, a reverse rotation converter module, a two-phase / three-phase AC converter module, a PWM converter, a three-phase AC induction motor, a magnetic flux linkage observer, and a battery pack; wherein, a control system conducts the control by means of speed and magnetic flux linkage closed loop, and a magnetic flux observer uses a current structure; the amplitude and phase of the magnetic flux of a rotor are solved by using three-phase stator current and the rotation speed of the motor, and the field orientation is realized; as the asynchronous motor is a nonlinear link coupled by multiple variables, decoupling and linearization can be achieved via the filed orientation, and therefore system calibration can be performed to obtain the desired dynamic performance. Therefore, by means of comparative and comprehensive researched into the direct torque control technology and vector control technology, the vector control AC frequency-variable speed regulation system has the advantages of solving the key technical problems of the frequency-variable speed regulation of the driving system of an electric automobile, and providing a more efficient technology for the driving system of the electric automobile.

The invention provides a synchronous reluctance motor sensorless direct torque control system based on power compensation. The system comprises a first subtractor, a first PI module, a second subtractor, a first adder, a torque hysteresis module, a third subtractor, a switch table module, a switch table module, a magnetic linkage hysteresis module, a second adder, a rectifier / inverter module, a stator voltage vector calculation module, a stator magnetic linkage and rotating speed estimating module, an actual motor torque calculation and angle compensation module based on active power calculation, a magnetic linkage given amplitude compensation module based on reactive power calculation, a stator current vector transformation module and a synchronous reluctance motor. The power output capacity of the system is improved by the method that a reactive power calculation output value compensates flux linkage stator flux linkage and an active power calculation output value compensates statorflux linkage angles.

The invention discloses a five-phase inverter and double three-phase motor system driving circuit and a direct torque control method. The system driving circuit comprises two star-winding three-phasemotors, a five-bridge arm inverter, a speed adjusting module, a PI regulator, a torque calculating module, a torque adjusting module, hysteresis controllers and a switch state selecting table. The control method adopts a torque hysteresis control way, torque errors are obtained after given torques and actual torques are adjusted by the torque adjusting module, the torque adjusting module is connected with the switch state selecting table through the hysteresis controllers, and PWM pulse width modulation signals of two motor inverters are acquired from the switch state selecting table. Advantages of the three-phase direct torque control method, such as a simple structure and strong robustness, are inherited; according to the optimized direct torque control method, the control accuracy is improved, the response speed is increased, and high-precision and fast-response control of double three-phase motors is achieved; the direct torque control method is suitable for various five-phase inverter and double three-phase motor systems.

The invention discloses a PMSM stator winding resistor asymmetric fault diagnosis method comprising the following steps: firstly injecting a DC signal into a linkage control loop in a PMSM direct torque control system, thus forming dc components in the three-phase stator winding current; secondly, measuring the three-phase stator winding current and zero sequence voltage and calculating the mean value thereof, and using the obtained three-phase stator winding current and zero sequence voltage mean value to estimate a three-phase stator winding resistor offset amount; finally, using the three-phase stator winding resistor offset amount to diagnose and position stator winding resistor asymmetric faults. The method is small in computational complexity, simple in operation, high in reliability, can accurately diagnose the PMSM stator winding resistor asymmetric faults, can position a fault phase, can reflect the fault level, and is not affected by the stator winding turn-to-turn short circuit fault.

The invention discloses a direct torque control system and method for improving motor torque performance. The direct torque control system comprises a torque regulator, a flux linkage regulator, a rotating speed regulator, a sector judgment module, a voltage vector option table generation module, a driving signal generation system, a duty ratio calculation module, a flux linkage observer for obtaining flux linkage information of a motor stator, a torque observer for obtaining electromagnetic torque information of the motor, and a rotating speed observer for obtaining the rotating speed of a motor output shaft. According to the direct torque control system and method, the motor can be effectively controlled.

The invention discloses a direct torque control system without a flux linkage loop. The direct torque control system comprises a motor and a control system. The control system comprises a coordinate transformation module for detecting three-phase currents ia, ib and ic and three-phase voltages ua, ub and uc at an output end of a three-phase inverter module and converting the currents and voltagesinto i[alpha] and i[beta], and u[alpha] and u[beta]; a torque and rotor position estimation module for estimating stator flux linkages [psi][alpha] and [psi][beta] and a rotor position [theta]r in accordance with i[alpha], i[beta], u[alpha], and u[beta], and calculating an observed torque value Te; a PI speed regulator for calculating a given torque value (shown in the description) according to the rotational speed of the permanent magnet synchronous machine; a reference vector generation module for generating reference voltages usd and usq according to the difference between the observed torque value Te and the constant torque value (shown in the description) and a torque angle [delta]; an SVM control module for synthesizing reference voltages usd and usq into optimal voltage vectors Sa,Sb and Sc; and a three-phase inverter module for outputting a three-phase alternating current according to the input optimal voltage vectors Sa, Sb and Sc to realize the control over the rotational speed of the permanent magnet synchronous machine.

The invention discloses an asynchronous motor direct torque control system and method regulating duty cycle based on rotating speed. The system comprises a motor state observation module, a voltage vector generation module, and a motor control module. The method comprises steps that the motor state observation module collects motor rotating speed, and instantaneous phase voltage and phase currentof a stator winding, and calculates electromagnetic torque, stator flux linkage amplitude and information of a sector in which the stator flux linkage is; the voltage vector generation module calculates offset of the stator flux linkage amplitude and offset of the electromagnetic torque by combining output of a rotating speed regulator and a set stator flux linkage amplitude of the system according to motor state information, generates a control signal through a torque controller and a flux controller, sends the control signal to a voltage vector selection table, selects a voltage vector and determines voltage vector action time; and the motor control module generates a drive signal according to the voltage vector and duty cycle information, so as to drive the motor to run. The asynchronous motor direct torque control system has a simple structure, torque response is fast, torque ripple of the motor is lowered, and running performance of the motor is improved.

The invention belongs to the technical field of motor speed control and relates to a speed sensorless control method for a motor with high precision and speed requirements. The speed sensorless control method comprises the steps of constructing a speed observer model by using an MRAS (Model Reference Adaptive System) principle; in order to utilize an SMC (Sliding Mode Control)-MRAS rotation speedidentification method, selecting a PMSM (Permanent Magnet Synchronous Motor) as a reference model and a stator current model as an adjustable model, and constructing a sliding mode surface S by usingoutput differences of the two models to improve the speed observation precision; meanwhile, replacing the conventional Sgn function with a Sigmoid function as a switching function in sliding mode control to establish a sliding mode observer model so that the system has better dynamic and static stability; then proving that the rotation speed observation method in combination with the MRAS and theSMC has strong robustness and good dynamic and static performance in the PMSM speed sensorless direct torque control system by changing the reference speed value and the load torque through operationsimulation of a Matlab / Simulink.

The invention discloses a direct torque control system and method of a six-phase motor. The direct torque control system is connected with a six-arm inverter and a six-phase double-Y-winding motor, middle points of six arms of the six-arm inverter are connected with six phases of winding terminals of the six-phase double-Y-winding motor correspondingly, each inverter arm of the six-arm inverter isformed by connecting two power switch tubes in series, a connecting point of the two power switch tubes in each inverter arm is the middle point of the corresponding arm, the two ends of the serial-connected power tubes are connected with anode and cathode of a DC power supply respectively, the former three inverter arms in the six-arm inverter form a first inverter, the latter three in the sameform a second inverter, and the direct torque control system obtains switch triggering signals of the first and second inverters to realize direct torque control for the six-phase double-Y-winding motor. According to the control system and method, calculation steps are simplified, the calculation difficulty is reduced, and control of high precision and rapid response is realized.

The invention discloses a direct torque control system and a method for reducing motor torque pulsation. The system comprises a motor situation observation module, a voltage vector generation module and a motor control module, wherein, according to the motor situation observation module, the motor output shaft rotate speed and stator winding transient line voltage and line current are collected during the course of motor operation, so that the motor situation information is figured out: current stator flux amplitude, electromagnetic torque, the sector where the stator flux is located in and the motor output shaft rotate speed. According to the motor situation information, combining with the motor current rotate speed, system setting rotate speed and system setting stator flux amplitude, the motor situation information is figured out through the voltage vector generation module, namely, the basic voltage vector and the time of the basic voltage vector function which is needed to be output through the current motor control module. According to the motor control information, the voltage vector which the motor needs is provided through the motor control module. The direct torque control system and the method for reducing motor torque pulsation has the advantages of significantly reducing motor torque pulsation and accurately and effectively controlling the motor.

The invention provides a direct torque control method for a permanent magnet synchronous generator. The direct torque control method comprises the steps that a nonlinear mathematical model of the permanent magnet synchronous generator in a coordinate system is built; a PI controller of a rotational speed control ring is designed, operation is conducted on a rotational speed instruction value and an actual measurement rotational speed value through the PI controller, and an instruction value of inner ring electromagnetic torque is obtained; a state equation with stator flux linkage amplitude and electromagnetic torque amplitude of the permanent magnet synchronous generator serving as state variables is built; a permanent magnet synchronous generator inverse system expression of a permanent magnet synchronous generator original system is worked out; a new pseudo-linear system is built; an equivalent linear subsystem of the pseudo-linear system is worked out; a sliding mode variable structure control law of the equivalent linear subsystem is designed through a variable exponent reaching law; the sliding mode variable structure control law is substituted into the inverse system expression, and a controlled quantity of the original system is obtained through inverse solution. According to the direct torque control method for the permanent magnet synchronous generator, linear decoupling control over the electromagnetic torque amplitude and the stator flux linkage amplitude in direct torque control of the permanent magnet synchronous generator is realized, and robustness of a whole system is high.

The invention discloses a direct torque control system. An output end of an internal torque giver is connected with an input end of a torque comparator / magnetic flux comparator, rotational speed setup is connected with the internal torque giver through a PID (proportion integration differentiation) adjuster after being compared with actual rotational speed feedback, magnetic flux optimizer and a magnetic flux brake are respectively connected with the internal torque giver, the output end of the internal torque giver and an output end of an adaptive motor model are connected with an input end of the torque comparator / magnetic flux comparator, an output end of the torque comparator / magnetic flux comparator is connected with an input end of an optimized pulse selector, and a main power supply circuit is used for optimizing the whole control system by using a control circuit for controlling and adjusting the torque of a motor. The direct torque control system has the advantages that by means of measurement of torque and magnetic flux, open and closed states of an inversion circuit are adjusted immediately, and then the torque and the magnetic flux are further adjusted so that precise control is achieved.

The invention provides a direct torque control method for a three-phase four-switch permanent magnet synchronous motor (PMSM) speed control system, comprising a step 1 of reconstructing six basic voltage vectors by using four unbalanced voltage vectors generated by a three-phase four-switch inverter; a step 2 of obtaining the position of the PMSM, and calculating the motor speed to obtain a reference torque given value Te; a step 3 of calculating a motor stator flux and a feedback torque, taking the motor torque and the stator flux as control objects to obtain output voltage components usq andusd; a step 4 of obtaining a reference voltage vector us according to the voltage components usq and usd, determining the sector of the voltage vector us, using a reconstructed effective voltage vector and a zero voltage vector in the sector as an alternative voltage vector, selecting an evaluation function, substituting the alternative voltage vector into the evaluation function G, and obtainingan output voltage vector ui by minimizing the evaluation function G. The method can achieve a precise torque control effect.

The invention discloses a direct torque control system and method of a brushless double-fed motor. Electromagnetic torque deviation, flux linkage amplitude deviation and a position where a flux linkage angle is located in a sector are fuzzed and then sent to a fuzzy controller, a duty ratio of an effective voltage vector with in a control period is determined according to an established fuzzy control rule, and the torque and the flux linkage pulse during direct torque control are reduced by respective action of the effective voltage vector and a zero vector for different time. The direct torque control system and method has the advantages that the torque pulse is effectively reduced on the basis of maintaining the advantage of traditional direct torque control, and the performance of the direct torque control is improved. The direct torque control system and method is particularly suitable for variable-frequency speed regulation of the brushless double-fed motor and application of a wind power generation control system.

The invention relates to a rotating speed adjustment method in an asynchronous motor direct torque control system. By modifying the traditional PI speed regulator in the direct torque control system,a new speed adjustment IP control method is obtained, so that the speed response time quickened, overshoot is reduced or even eliminated and the anti-interference property of the system is also enhanced, thus further improving the rapidness, accuracy and robustness of the asynchronous motor direct torque control system in the control of rotating speed.