99 results about "Rotating reference frame" patented technology

The invention discloses a control method of MMC-HVDC (multi media card-high voltage direct current) during power grid malfunction of a receiving end. The control method includes following steps: 1, measuring to acquire a voltage instantaneous value and a current instantaneous value of a transformer outlet; 2, acquiring a positive sequence voltage d axis component, a positive sequence voltage q axis component, a negative sequence voltage d axis component and a negative sequence voltage q component through a 1 / 4 periodic signal delay principle, separating the positive and negative sequence components, and obtaining positive and negative sequence components of a network voltage under a synchronous rotating reference frame through coordinate transformation; and 3, dividing a voltage equation into a positive sequence equation and a negative sequence equation, and indicating the positive sequence components and the negative sequence components of various electrical capacities respectively by superscript P and N. The control method has the advantages of enabling a flexible direct current system to have unsymmetrical fault ride-through ability and the like.

Motion estimation methods using multiple reference frames are provided. In the methods, motion estimation is performed on a current block using a single reference frame selected from the multiple reference frames or using the multiple reference frames in order of probability that each reference frame is an optimal reference frame for the current block. Accordingly, faster motion estimation is performed.

The invention provides a second-order generalized integrator-based control method for a single-phase gird-connected inverter. Two-phase orthogonal fundamental current signals are reconstructed by a second-order generalized integrator; decomposition of a fundamental active component and a fundamental reactive component of a current in a synchronous rotating reference frame, so that decoupling control on the active component and the reactive component of the fundamental current is achieved; observation and control on output current harmonics of the inverter are achieved by the reconstructed fundamental current signals; and power quality of a single-phase grid-connected system is improved. The control method is simple, feasible, and insensive to an input signal, and meets the dynamic and static properties of the system. Compared with a traditional control strategy, the system can still be kept stable and has relatively good engineering practice value under the conditions of an amplitude drop and a frequency change of an input signal.

The invention discloses a rotating speed evaluation method used for speed-sensorless induction motor vector controlling. Based on an induction motor two-phase synchronous rotating reference frame state equation, the method discloses a rotating speed evaluation method with stator resistance identification. On the basis that a field current differential equation and a torque current differential equation are respectively utilized to evaluate the rotating speed, by utilizing the equivalent relationship of the both equations, the on-line identification of the stator resistance is realized. By updating the stator resistance value in real time, the above rotating speed evaluation scheme is improved. According to the invention, synchronous speed evaluation is realized without using rotor or stator linkage and without rotor resistance, and the influence of low velocity region stator resistance also is effectively improved. The method has the advantages of clear theory deduction step, simple model, high precision of rotating speed tracking, strong robustness to motor parameter change. The method is suitable for high precision controlling and has large theory innovation and application value.

The invention provides an excitation control device of a brushless doubly-fed motor independent power generation system and belongs to a power generation control device for a brushless doubly-fed motor. According to the technical scheme of the invention, the defects in the prior art that, an existing scalar control method is poor in dynamic performance and a conventional bisynchronous rotating reference frame is complicated in vector control, high in cost and low in efficiency can be overcome. According to the technical scheme of the invention, the device comprises a PW voltage magnitude controller, a PW voltage frequency controller, a CW current vector controller, an LC filter, a rotating speed calculator, a CW current frequency feed-forward amount calculator, a PW voltage phase-locked loop and a PW current converter. The CW current vector controller of a brushless doubly-fed motor is adopted as an inner ring, while the PW voltage magnitude controller and the PW voltage frequency controller of the brushless doubly-fed motor are adopted as an outer ring. In this way, the PW voltage magnitude and the PW voltage frequency are independently controlled. Meanwhile, a cross feed-forward compensation mechanism is adopted in the CW current vector controller, so that the device is faster in response rate and better in stability precision. The constant-frequency and constant-voltage generating function of the brushless doubly-fed motor independent power generation system in the speed-varying and load-varying condition is realized.

The invention relates to a permanent magnet synchronous motor current increment prediction algorithm which comprises the following steps: (1) a stator d shaft voltage equation and a stator q shaft voltage equation of a permanent magnet synchronous motor in a synchronous rotating reference frame are established; (2) according to the stator q shaft voltage equation in the step (1), discrete voltage equations of the permanent magnet synchronous motor are established in the current period and the previous period respectively; (3) changes in voltage items relevant to rotating speed are ignored, and the discrete voltage equations of the permanent magnet synchronous motor are subtracted to obtain a current increment formula of the permanent magnet synchronous motor; (4) a pulse transfer function between a current predicted value and a current detected value in the current period is obtained according to a transfer function of the permanent magnet synchronous motor and the current increment formula of the permanent magnet synchronous motor; (5) a closed loop pulse transfer function of a q shaft current loop by means of the current increment prediction algorithm is obtained according to the pulse transfer function, a pulse transfer function of a traditional current loop PI regulator, and the transfer function of the permanent magnet synchronous motor. The permanent magnet synchronous motor current increment prediction algorithm can be widely applied to the field of permanent magnet synchronous motor servo control.

A phase-locked loop and method for estimating a phase angle of a three-phase reference signal is disclosed, which includes an adaptive quadrature signal generator configured to calculate an estimated first state and an estimated second state of a model of an unbalanced three-phase system at a fundamental frequency of the reference signal on a basis of the reference signal and an estimated fundamental frequency; a reference frame transformation block configured to calculate a direct component and a quadrature component in a rotating reference frame synchronous with an estimated phase angle on a basis of the fundamental positive sequence component and the estimated phase angle, and configured to determine an estimate of an amplitude of the fundamental positive sequence component on the basis of the direct component; and an estimator configured to determine estimates of the estimated fundamental frequency and the estimated phase angle on the basis of the quadrature component.

The invention discloses a phase-locked loop applicable to power grid voltage unbalance and distortion states, and belongs to the related technical fields of power grid voltage phase signal detection and power grid load harmonic current extraction. The phase-locked loop provided by the invention aims to solve the problem as follows: the conventional synchronous rotating reference frame based three-phase digital phase-locked loop cannot accurately detect the phase value of the three-phase voltage fundamental wave positive-sequence component under power grid voltage unbalance and distortion states; consequently, the precision of a related harmonic current extraction algorithm is lowered, and the compensation effect of a harmonic compensation apparatus is weakened. The phase-locked loop provided by the invention improves the conventional three-phase digital phase-locked loop, and a repetition controller is introduced; the repetition controller is connected with a proportional integral controller in parallel to form a new controller, so that the excellent steady-state performance of the repetition controller is combined with the excellent dynamic performance of the proportional integral controller; and therefore, the phase-locked loop has the advantages of high dynamic response, high detection precision and the like. The phase-locked loop is mainly applied to voltage phase detection under power grid voltage unbalance and distortion states.

Video compression utilizes filterings and / or warpings of the reference frames for motion estimation and motion compensation. The presence of affine, fade, or blur is determined. If present, filters and / or warpings are applied to reference frames and motion is estimated using reference frames plus any filtering / warping reference frames.

The invention relates to a multi-phase induction motor-specific subharmonic current suppression method, which includes the following steps: (A) current reference value processing; (B) current feedback value processing; (C) current regulation; (D) voltage reference value determination. Based on the vector control of a multi-phase induction motor, the method maps the current of the multi-phase motor into a corresponding synchronous rotating reference frame of a fundamental wave and each subharmonic orthogonal to each other by multiple synchronous rotating coordinate transformations, and uses proportional-integral controllers to respectively carry out tracking with zero steady-state error and combine to form an integral current controller. The method has the advantages that trapezoidal integration is adopted to increase integral accuracy, and supplemented by variable structure control, appropriate self-adaptive compensation is introduced to resist control saturation, so that static and dynamic performance is further enhanced; the method can suppress motor loss caused by the harmful subharmonic current of the multi-phase motor and the adverse affection of torque ripple, vibration noise and the like, and can utilize the positive effect of usable subharmonic; the method takes full advantage of the multi-phase motor, and enhances system performance.

The invention discloses a three-dimensional face point cloud nose tip detection method and a data processing device using the same. Super voxels are utilized to perform efficient segmentation on three-dimensional point cloud data, a super voxel neighborhood is utilized to enhance a matching capability between face partial structures, and relative geometric transformation between a face posture and a training sample face posture is estimated and tested in combination with a partial reference frame, thereby correcting a generalized Hoff voting process of a three-dimensional face nose tip position, and improving face nose tip position estimation accuracy and reliability of a system.

The invention discloses a doubly fed wind power generator control structure under asymmetric sudden rise of power grid voltage. In doubly fed wind power generator rotor excitation control, an active damping coefficient R1 is introduced into a rotor negative sequence current inner loop, the product of the active damping coefficient R1 and a negative sequence feedback current of d-q axis of a rotor is added onto output of a rotor negative sequence current d-q axis regulator so as to form an active damping control structure of the rotor side negative sequence current inner loop, an active damping coefficient R2 is introduced into a stator negative sequence current outer loop, and the product of the active damping coefficient R2 and a d-q axis negative sequence feedback current of a stator is added onto output of a stator negative sequence current d-q axis regulator so as to form a rotor converter double synchronous rotating reference frame improvement control strategy based on active damping. The doubly fed wind power generator control structure can effectively suppress oscillation of rotor negative sequence currents and electromagnetic torque, and a transient process of suppressing a stator negative sequence current when the power grid voltage suddenly rises asymmetrically is accelerated, and furthermore ability of system dynamics responses is improved.

The invention discloses a positive- and negative-sequence combined control method for a three-phase PWM current transformer when a power grid is imbalanced. The combined control of positive-sequence and negative-sequence currents is realized in a positive-sequence dq synchronous rotating reference frame, the control system is simplified, and the normal and stable operation of the PWM current transformer is ensured when the voltage of the power grid is imbalanced. To solve the problem of separation of positive-sequence and negative-sequence vectors of the power grid voltage, a novel positive-sequence and negative-sequence vector separation method in the positive-sequence dq synchronous rotating reference frame is provided such that only a primary positive- and negative-sequence voltage extraction module is needed, and a positive- and negative-sequence extraction module is omitted. For the inner-loop control of current, a PI+R type composite controller method is provided, and a resonant frequency of a resonance controller is configured to be 2[omega], so that zero steady-state error control for the negative-sequence component in the dq synchronous rotating reference frame is realized. Besides, in order to increase the response speed of the control system, a voltage feedforward control method is adopted according an output voltage and current vector model of the PWM current transformer, so that the dynamic performance of the control system is improved.

The invention relates to a method for controlling harmonic currents in a synchronous rotating reference frame by several times. Compensated harmonic currents at a certain time are converted to the synchronous rotating reference frame with the same times of rotating speeds and directions, harmonic instruction current information of an SFR is fully utilized, AC disturbance quantity brought by other nonsynchronous current components in the SFR is removed through a simple algorithm, so that the DC quantity corresponding to the compensated currents at the time in the SFR is extracted, and PI static-error-free decoupling control is achieved. The stability margin and the dynamic response speed of a control system can be effectively improved, and the steady state errors of the system are removed.

The invention discloses a decoupling control method for multiple-phase permanent magnet fault tolerant motor. The invention is characterized in that: (a) create the mathematical model of permanent magnet fault tolerant motor under multiple-phase still reference frame and deduce transformation matrix from multiple-phase still reference frame to two-phase rotating reference frame; (b) control d-axis (id=0) of stator current under two-phase rotating reference frame and independently control electromagnetic torque Td control of cross-axis (iq) of stator current to realize decoupling control of the current, the flux linkage, and the torque of multiple-phase permanent magnet fault tolerant motor. The transformation matrix of decoupling of stator flux linkage and rotor position angle theta is determined by Space Vector transform to realize decoupling control of flux linkage for multiple-phase permanent magnet fault tolerant motor. The control method provides permanent magnet fault tolerant motor with small overshoot, high control precision, and high response speed. The electromagnetic torque can get stable in 1S-2S during load fluctuation. The motor can give good dynamic and static performance.

The invention discloses a calculation method for sub-frequency harmonic compensation of an APF under multiple synchronous rotating reference frames. The calculation method comprises the following steps that after two-phase Clarke transformation is carried out on system voltage, positive-sequence Park transformation and negative-sequence Park transformation are carried out respectively, so that DC components VPd and VPq under a positive-sequence coordinate system and DC components VNd and VNq under a negative-sequence coordinate system are obtained, positive-sequence and negative-sequence decoupling filtering processing is carried out on the DC components VPd and VPq under the positive-sequence coordinate system and the DC components VNd and VNq under the negative-sequence coordinate system at a D_Couple module, and therefore the feedforward quantity of reference voltage output by the APF is obtained. Phase-locked loop calculation is used for obtaining the phase of the system voltage, so that the phase of the feedforward quantity of the reference voltage output by the APF is provided. Compared with the prior art, the method has the advantages that the calculation method for sub-frequency harmonic compensation of the APF under the multiple synchronous rotating reference frames prompts that each order of harmonic current is independently processed and quickly responded, and it is guaranteed that compensation for each order of harmonic is independently set.

The invention relates to the field of medicine, in particular to a head surgery navigation method based on three-dimensional scanning. The method includes the following steps: (1) performing preoperative CT scanning on a patient's head; (2) mounting calibration reference frames, reference reference frames and stereo vision equipment; (3) acquiring three-dimensional models of the patient's head, the reference reference frames and all correction reference frames by adopting the three-dimensional scanning equipment, and fitting characteristic points; (4) acquiring spatial coordinates of the reference reference frames and all correction reference frames by adopting stereo vision; (5) correcting the visual space error through an error correction model; (6) performing point cloud registration ona CT model of the patient's head and a head model constructed by the three-dimensional scanning equipment; (7) acquiring coordinate systems of the target reference frames through stereo vision in real time, and displaying the position of the equipment in CT space in real time in navigation software. The method can avoid navigation deviation caused by mark deviation before operation and during operation, so that the accuracy of operation navigation is improved.

A D-Q or rotating reference frame control system for a switched reluctance motor (SRM) provides a negativity removal module and a non-linear model module. As such, the control system utilizes control inputs fq and fd, which are converted into the ABC domain as electrical current functions f′ix with negative values. The negativity removal module is configured to share the torque portion of the negative values of the electrical current functions f′ix for each of the three phases of the SRM motor to remove the negative values. The non-linear module corrects the non-linearity of the SRM to smooth the torque that is output. The control system also utilizes a phase advancing module, which outputs fd for achieving a wide range of operating speeds.

The invention belongs to the field of wind-driven generator control technology and relates to a double-fed wind power generation system side converter back-stepping variable structure control system. The invention discloses a double-fed wind power generation system side converter back-stepping variable structure control system and method and a double-fed wind power generation system based on the system, and the system comprises a mathematical model establishment unit (11), a current instruction value calculation unit (12), a back-stepping variable structure control unit (13) and a space vector pulse width modulation unit (14); the method is based on Liapunov stability theory, back-stepping variable structure control algorithm design is performed under a two-phase synchronous rotating reference frame wind-driven generator mathematical model, and active and reactive power decoupling control of the system is realized; in order to eliminate disturbance influence in system actual operation, a variable structure control step containing an uncertain degree PI prediction scheme is added, so that sub-systems can satisfy Lyapunov asymptotic stability conditions when suffering from the disturbance. The dynamic property of the double-fed wind power generation system is further improved, and the parameter robustness of the system is enhanced.

A method for aligning visual-inertial odometry (VIO) and satellite positioning system (SPS) reference frames includes obtaining a plurality of range-rate measurements of a mobile platform from an SPS. The range-rate measurements are with respect to a global reference frame of the SPS. The method also includes obtaining a plurality of VIO velocity measurements of the mobile platform from a VIO system. The VIO velocity measurements are with respect to a local reference frame of the VIO system. At least one orientation parameter is then determined to align the local reference frame with the global reference frame based on the range-rate measurements and the VIO velocity measurements.

The invention relates to a six-phase alternating current motor harmonic current control strategy. Negative-sequence five-time and positive-sequence seven-time harmonic current detection and loop control are added on a conventional three-phase alternating current motor control method. A locking phase of a first stator not only outputs a magnetic chain angle and a magnetic chain frequency of the first stator and the negative-sequence six-time angle and the positive-sequence six-time angle are added. According to the design phase errors of the two stators, the magnetic chain angle of the second stator and the negative-sequence six-time angle and the positive-sequence six-time angle of the second stator are output; afterwards, according to features of two stator currents on a synchronous rotating reference frame, the negative-sequence five-time current components and the positive-sequence seven-time harmonic current components of stator currents are decomposed. Loop control is carried out on the negative-sequence five-time currents and the positive-sequence seven-time currents. A control result is converted through coordinates and stacked on the synchronous rotating reference frame, and the base wave currents are used for controlling the output base wave control voltage. Afterwards, the control result undergoes inverse transformation of synchronous rotation coordinates, a PWM module outputs pulse-width waves and a corresponding converter power unit composed of power electronic components is controlled.

In one aspect, in general, the invention features a control system configured for use with a three-phase PWM converter. The control system receives an input signal from a three-phase power supply and provides an output signal at a DC link. A voltage-separating module generates on the basis of the input signal a positive sequence voltage component and a negative sequence voltage component in a rotating reference frame. A reference current computation module uses at least the positive sequence voltage component and the negative sequence voltage component to compute a first reference current and a second reference current. A current regulating module uses at least the first reference current and the second reference current to generate a command signal. The command signal is provided to a driving circuit of the three-phase PWM converter for generating a regulated DC bus voltage at the DC link.

The invention discloses a bidirectional motion estimation device for production of an interpolated frame based on a front reference frame and a rear reference frame, which comprises a storage unit, a matching error calculation unit, a comparator tree unit and a data memory. The storage unit is used for caching data in the front reference frame and the rear reference frame; the matching error calculation unit is used for dividing the interpolated frame into a plurality of macro blocks of the same size, setting a search range based on each macro block, and calculating matching errors corresponding to all motion vectors in the search range; the comparator tree unit is used for comparing all the matching errors calculated in the search area to obtain the minimum matching error and outputting the minimum matching error and a corresponding motion vector; and the data memory is used for storing the minimum matching error and the corresponding motion vector. The full-search bidirectional motion estimation method can be implemented flexibly, and the efficiency of implementation is high; the driving capacity of signals can be improved, the delay of the signals can be reduced, and the signal synchronization can be controlled; the highest efficiency and data multiplexing can be realized; and the bidirectional motion estimation device has higher flexibility and practicality.

The invention provides a control algorithm for a single-phase unified power quality regulator, which detects a compensation load terminal voltage and inhibits a power voltage harmonic on the basis of an instantaneous reactive power theory, and has a harmonic current compensation function. The control algorithm constructs a virtual two-phase circuit by a detected single-phase system signal, reconstructs a two-phase orthogonal fundamental wave current signal and achieves decomposition of active and reactive components of a current fundamental wave under a synchronous rotating reference frame; observation and control on the voltage harmonic and the current harmonic are achieved by the harmonic voltage signal and the reconstructed fundamental wave current signal; and the power quality of a single-phase system is improved.

The invention provides a sensorless control method and control system for an internal permanent magnet synchronous motor. The method comprises the following steps: respectively injecting high-frequency voltage signals into shafts of an estimated rotor synchronous rotating reference frame, exciting the motor to generate a current response signal sum as a feedback signal of a current ring; enablingthe sum to obtain high-frequency current signal sum through band-pass filtering; multiplying the sum for modulation, and enabling the modulation result to obtain an estimated positional deviation signal epsilon(delta theta) through low-pass filtering; carrying out PI adjustment on epsilon(delta theta) to obtain estimated rotor angular velocity; carrying out integration to obtain estimated rotor position, setting rotor angular velocity omega ref and carrying out PI adjustment to obtain shaft current set value, wherein the shaft current set value is 0; controlling a difference value with actualrotor position to be converged to be 0 so that the motor operates stably. According to the control method, the influence of factors such as stator resistance and motor fundamental frequency can be reduced, and the accuracy of rotor position detection is improved.

A motion estimation method is provided for generating a motion vector of a to-be-generated frame between two continuous reference frames. The method includes the following steps. A candidate motion vector is obtained according to the position of a to-be-generated block of a to-be-generated frame. Two first reference blocks are obtained from the two reference frames by extending the candidate motion vector from the to-be-generated block to the two reference frames, respectively. Two second reference blocks are obtained from the two reference frames by extending the candidate motion vector from one reference frame to another reference frame. Whether the candidate motion vector is valid is determined according to the positions of the two reference blocks obtained in each obtaining step. The corresponding motion vector of the to-be-generated block is determined according to the valid candidate motion vector.

Presented is a harmonic regulator that regulates a plurality of individual harmonics in a system having periodic torque disturbances to commanded values, including zero. For each harmonic being regulated, a feedback signal having at least one harmonic component due to the harmonic being regulated is transformed from a source reference frame to a harmonic reference frame of the harmonic being regulated to form a qd feedback signal. The qd feedback signal is subtracted from the commanded value to form a qd signal and regulated. The regulated qd signal is transformed to a destination reference frame to form a compensation signal and the compensation signal is added to a control signal to form a qd control signal that drives each harmonic being regulated towards the commanded value.

The invention discloses a decoupled current droop control method of a shunt chopper in a microgrid, and belongs to the field of coordination control of the shunt chopper in the microgrid. Different from traditional droop control, according to the method, there is no need to calculate output power of inverters, a virtual current vector having the same phase position with a voltage vector is generated by conducting rotation transformation on a current vector, and accordingly a droop relationship between the voltage and the virtual current is built under a synchronous rotating reference frame. By designing parameters reasonably, the droop relationship can naturally form control characteristics of virtual impedance to compensate decrease of the current equipartition effect caused by difference of line impedance. Besides, a voltage phase-locked loop based on a proportional regulator is adopted for generating a reference value of a voltage frequency, and compared with a traditional phase-locked loop based on a proportional-integral regulator, the phase-locked loop in the method can ensure that the shunt chopper is operated synchronously with an equal status, and maintain the redundancy. According to the decoupled current droop control method of the shunt chopper in the microgrid, the precise equipartition of a load current among inverters can be achieved.

A single stage DAB control circuit for converting an unbalanced grid voltage into a DC voltage is provided. The control circuit includes a controller having a voltage detection module, a first transformation module, a level shift module, and a second transformation module. The voltage detection module provides voltage component values that are indicative of the voltage in each phase of a three-phase AC power supply. The first transformation module converts the voltage component values from a stationary reference frame into reference voltage signals in a rotating reference frame using a Clarke-Park transform. The level shift module compensates the reference voltage signals to simulate an ideal or balanced three-phase AC voltage. The second transformation module converts the compensated reference voltage signals from the rotating reference frame to the stationary reference frame using an inverse Clarke-Park transform. The controller is then operable to control operation of a single stage DAB converter for providing a DC charging voltage to a battery that is substantially free of fluctuations or ripple.