98 results about "Rotating reference frame" patented technology

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 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.

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.

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 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 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 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.

A method of controlling an inverter to includes determining the components of a phasor representing the output current from the inverter in a fixed reference system; determining the components of the current phasor in a reference system rotating at a velocity equal to the velocity of rotation of the phasor representing the grid voltage; and comparing the components of the current phasor in the rotating reference system with a reference, again expressed in the rotating reference system, to determine an error signal, by means of which the inverter is controlled.

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.