432 results about "Space vector modulation" patented technology

A system and method for efficiently capturing electrical energy from a variable-speed generator are disclosed. The system includes a matrix converter using full-bridge, multilevel switch cells, in which semiconductor devices are clamped to a known constant DC voltage of a capacitor. The multilevel matrix converter is capable of generating multilevel voltage wave waveform of arbitrary magnitude and frequencies. The matrix converter can be controlled by using space vector modulation.

Three-level inverter and rectifier power conversion systems and space vector modulation (SVM) controls having even-order harmonic elimination for neutral voltage balancing with a predefined vector switching sequences for half-wave symmetry in open loop system operation. The vector sequence listings for each SVM diagram segment includes switching state entries individually indicating one of three possible switching state levels positive (P), zero (0), or negative (N) for each of three or more switching groups of the power conversion system, with listings for each pair of first and second diametrically opposite diagram segments include symmetrically opposite switching states, with positive levels in the entries of the listing for the first segment corresponding to negative levels in the entries of the listing for the second segment and vice versa.

The invention discloses an automatic vehicle body color recognition method of an intelligent vehicle monitoring system. The method comprises the following steps: firstly detecting a feature region on the behalf of a vehicle body color according to the position of a plate number and the textural features of the vehicle body; then, carrying out color space conversion and vector space quantization synthesis on pixels of the vehicle body feature region, and extracting normalization features of an obscure histogram Bin from the quantized vector space; carrying feature dimension reduction on the acquired high-dimension features by adopting an LDA (Linear Discriminant Analysis) method; carrying out various subspace analysis on the vehicle body color, then carrying out vehicle body color recognition of the subspaces by utilizing the recognition parameters of an offline training classifier, and adopting a multi-feature template matching or SVM (Space Vector Modulation) method; and finally, correcting color with easy intersection and low reliability according to the initial recognition reliability and color priori knowledge, so as to obtain the final vehicle body recognition result. The automatic vehicle body color recognition method is applicable to conditions of daylight, night and sunshine and is fast in recognition speed and high in recognition accuracy.

The invention discloses a space vector modulation based harmonic current compensation system for a high-speed permanent magnet motor. The system comprises a rotor position and speed observation module, a stator phase current harmonic compensation module, a phase current feedback module, a rotation speed PI adjustment module, a current PI adjustment module and an SVPWM (space vector pulse width modulation) conversion output module. The stator phase current harmonic compensation module comprises a harmonic current extraction module, a proportional controller, a harmonic current adjustment module and a harmonic voltage compensation amount calculation module. The harmonic current extraction module extracts phase current harmonics of a permanent magnet synchronous motor in real time by the aid of an adaptive band-pass filter; the proportional controller adjusts the harmonic current and feeds the harmonic current to a current loop; the harmonic current adjustment module and the harmonic voltage compensation amount calculation module are used for calculating harmonic voltage compensation amount on the basis of a mathematical model of the high-speed permanent magnet motor and feeding back to the voltage loop. By the space vector modulation based harmonic current compensation system for the high-speed permanent magnet motor, voltage compensation amount can be calculated accurately, real-time compensation can be realized, phase current waveforms in operation of the permanent magnet synchronous motor can be improved effectively, torques and rotation speed pulses can be reduced, and accordingly operation efficiency, stability and reliability of the motor can be improved.

The invention relates to a permanent magnet synchronous motor low inverter power consumption direct torque control method and device. The permanent magnet synchronous motor low inverter power consumption direct torque control method adopts predictive control strategies. Compared with the space-vector-modulation-based direct torque control and the common direct torque control, the permanent magnet synchronous motor low inverter power consumption direct torque control method has the advantages of enabling the integral inverter switching frequency to be the lowest, optimally using a power device and reducing the switching loss of the inverter due to the facts that predicted values of the torque and the stator flux linkage are predicated according to an interior model of a controller based on the given reference values of the torque and the stator flux linkage and a most suitable switching position for the inverter is obtained through a minimization objective function which comprises the flux linkage, the torque and the average switching frequency within the forecast time domain and enabling online computing time to be greatly reduced due to the fact that the control law is fed back through an offline computing state, maintaining good dynamic performance and robustness of the common direct torque control and maintaining the flux and the torque to be within a corresponding hysteresis range.

The invention belongs to the field of wind generator power conversion device control, and relates to a constant-frequency direct power control method for a PWM converter under the condition of power grid voltage imbalance. The method comprises the following steps of: determining a sampling frequency; acquiring a three-phase power grid voltage, a three-phase power grid current and a direct-current side voltage, and calculating resultant vectors E and I of the power grid voltage and the power grid current in a three-phase static coordinate system respectively; calculating positive and negative sequence components of the power grid voltage and the power grid current; calculating an instantaneous power and an instantaneous power error; calculating a converter reference voltage, and performing inverse transformation on the converter reference voltage; performing amplitude limit on the converter reference voltage to obtain the resultant vector of the converter reference voltage after the amplitude limit; and modulating the resultant vector of the converter reference voltage after a space vector modulation algorithm is adopted for amplitude limit, and outputting the converter voltage. The method can inhibit the active power fluctuation of the system more effectively and greatly reduce the harmonic wave of the alternating-current side current; and the output converter voltage switch frequency is constant, so the output filter parameter design is simpler.

Current source converter drives and common mode voltage reduction techniques are presented in which a space vector modulation zero vector for current source inverter (or rectifier) control is selected according to the switching state of the current source rectifier (or inverter) and according to the AC input power and the AC output power to control the output common mode voltage.

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.

A power conversion system having a DC power distribution bus includes multiple power converters connected to the DC power distribution bus with modulation frequencies synchronized so that providing phase shifts between the different modulations has the effect of compensating voltage and current ripples, e.g., reducing voltage fluctuations, across the DC bus. Power conversion may be controlled using space vector modulation implemented, for example, by any of a variety of pulse width modulation schemes. Phase shifts in which nulls of the modulation cycles of different converters do not overlap (in the time domain) may be particularly effective for DC bus voltage ripple compensation. The novel method for DC bus voltage ripple compensation may be implemented by programming a digital signal processor to control the power converters.

Control systems, methods and power conversion systems are presented for controlling harmonic distortion, in which multi-sampling space vector modulation (SVM) is employed for controlling power converter switching devices, with a reference vector being sampled two or more times during each SVM period to update the SVM dwell times more than once during each SVM cycle.

A motor driver has a plurality of output circuits each having an upper side switch and a lower side switch connected in series for supplying a current to a motor. The motor driver includes a current detection resistor connected in series with the plurality of output circuits in common for detecting a current supplied to the plurality of output circuits, a position detection circuit for outputting a position signal corresponding to a position of a rotor of the motor, a current command generation circuit for generating a target current command signal based on the position signal and a predetermined phase angle in which a phase angle of the target current command signal is determined by the predetermined phase angle, and a space vector modulation based logic control circuit for commanding a plurality of output circuits that are set in a plurality of switches states for control of an electric motor.

The invention, which belongs to the power converter control field of the driving motor, relates to a method for controlling neutral point voltage balance of a three level converter, wherein the method is based on a voltage space vector pulse width modulation technology and is used for controlling a neutral point clamped three level inverter. The method comprises the following steps that: step one, an action time distribution factor of a redundant small vector is obtained; step two, an area where control on a neutral point potential balance can be realized by a nearest three vector (NTV) method is obtained; step three, an NTV action area in a mixed voltage space vector pulse width modulation method is obtained; step four, a switching condition of the mixed voltage space vector pulse width modulation method is designed; and step five, the mixed voltage space vector pulse width modulation method with a proportion of pm is realized. According to the invention, a redundant small vector distribution factor is employed to design a switching condition of a mixed voltage space vector pulse width modulation strategy; therefore, an essence of a space vector modulation method is embodied; themethod can be used flexibly and used variables are less, so that it is beneficial for analysis and development application.

In a PWM space vector modulation inverter motor drive system, PWM cycles are modified to permit motor phase currents to be reconstructed as observable on the DC bus link. The PWM cycles are modified near sector boundaries so that measurements taken at the DC bus link correspond to actual motor phase currents. With this technique, a single DC bus current measure can be used to reconstruct all motor phase currents, while also providing fault protection.

The invention discloses a permanent magnet synchronous motor predicted current control method and system based on FOSMC; the method comprises the following steps of carrying out comparing on the rotorangular speed and a given rotating speed to obtain a rotating speed difference, and inputting the rotating speed difference into a fractional order sliding mode controller; next, enabling an equivalent current of a dq axis at the current moment to pass through a sliding mode disturbance observer to obtain a voltage compensation quantity and a current estimation value under the parameter change, and enabling the current estimation value and the reference current at the next moment to be input into a non-differential-beat current prediction controller; and finally, carrying out compensating onthe obtained voltage vector and the voltage compensation amount of the dq axis at the current moment, carrying out coordinate transformation, space vector modulation and inversion, and obtaining a three-phase voltage to the permanent magnet synchronous motor, so that the stable operation of the motor is ensured. According to the method and the system disclosed by the invention, fractional order calculus and sliding mode variable structure control are combined, the fractional order calculus has more freedom degree, and the shaking of the system in the sliding mode process can be weakened, so that the control precision of the rotating speed is improved.

The invention discloses an automatic segmentation method of a knee joint cartilage image. The method is characterized by comprising edge positioning based on SVM (Space Vector Modulation) and image segmentation based on a region growing method, wherein the step of edge positioning based on the SVM comprises acquisition and conversion of a knee joint MRI (Magnetic Resonance Imaging) image, adaptive Canny edge detection and cartilage edge classification based on the SVM; and in the step of image segmentation based on the region growing method, cartilage tissues are segmented by mainly adopting the improved region growing method capable of automatically selecting seed points. The method has the beneficial effects that the cartilage segmentation is performed on the knee joint MRI image; the precision positioning is realized by effectively combining the mode recognition with the edge detection; and the positioning complementation is sufficiently implemented in combination of the region growing method, so that the internal similar characteristics and the external difference characteristics of regions to be segmented are combined. Thus, the defects of result over-segmentation or inaccurate segmentation and the like of traditional segmentation method are effectively overcome.

The invention discloses a load disturbance compensation device of a permanent magnet synchronous motor. The load disturbance compensation device comprises a load moment recognition sliding-mode observer and the like. The permanent magnet synchronous motor is connected with a PARK conversion module, a PARK inverse transformation module, a velocity calculation module and a CLARK conversion module respectively. The velocity calculation module is both connected with a first summator and the load moment recognition sliding-mode observer. The first summator and a second summator are both connected with a speed ring PI regulator. The CLARK conversion module is connected with the PARK inverse transformation module. The PARK inverse transformation module is connected with the load moment recognition sliding-mode observer, a fourth summator and a third summator. The load moment recognition sliding-mode observer is connected with a load moment recognition value feed-forward compensation factor unit. The load moment recognition value feed-forward compensation factor unit is connected with the second summator. The second summator is connected with the fourth summator. The fourth summator is connected with an electric current loop PI regulator. The third summator is connected with the electric current loop PI regulator. The electric current loop PI regulator is connected with the PARK conversion module. The PARK conversion module is connected with a space vector modulation module, the space vector modulation module is connected with a rectification/three-phase inverter module, and the rectification/three-phase inverter module controls the permanent magnet synchronous motor to operate.

The invention discloses a quasi-sensorless position servo controlling device for a permanent magnet synchronous motor and a method thereof. The quasi-sensorless position servo controlling device comprises a permanent magnet synchronous motor which is provided with a HALL sensor, etc. The HALL sensor is connected with a quasi-sensorless controlling module. The quasi-sensorless controlling module is connected with a fifth subtractor, a position/speed integrated controller, a third substractor, a fourth substractor, a PI regulator and an IPark conversion module respectively. The fifth substractor is connected with the position/speed integrated controller. The position/speed integrated controller is connected with the third substractor. The PI regulator is connected with the third substractor, the fourth substractor and the IPark conversion module respectively. The IPark conversion module is connected with a space vector modulation module. The space vector modulation module is connected with a three-phase inverter. The three-phase inverter is connected with the permanent magnet synchronous motor.

Three-level inverter and rectifier power conversion systems and space vector modulation (SVM) controls having even-order harmonic elimination for neutral voltage balancing with a predefined vector switching sequences for half-wave symmetry in open loop system operation. The vector sequence listings for each SVM diagram segment includes switching state entries individually indicating one of three possible switching state levels positive (P), zero (0), or negative (N) for each of three or more switching groups of the power conversion system, with listings for each pair of first and second diametrically opposite diagram segments include symmetrically opposite switching states, with positive levels in the entries of the listing for the first segment corresponding to negative levels in the entries of the listing for the second segment and vice versa.

A self-adaption reverse-pushing controlling permanent magnet synchronous motor direct torque control (DTC) system comprises an inverter which is connected with a signal detecting circuit and a permanent magnet synchronous motor, the permanent magnet synchronous motor is connected with the signal detecting circuit and a processor, and the signal detecting circuit is connected with the processor which is connected with the inverter. The inverter outputs three-phase alternating current to the permanent magnet synchronous motor, current signals of the permanent magnet synchronous motor are output to the signal detecting circuit, rotating speed pulse signals of the permanent magnet synchronous motor are output to the processor, the current signals of the signal detecting circuit are output to the processor, and the processor outputs switch signals to the inverter. A control method of the self-adaption reverse-pushing controlling permanent magnet synchronous motor DTC system utilizes the self-adaption reverse-pushing control theory, a speed reverse-pushing controller and a flux linkage torque self-adaption reverse-pushing controller are utilized for being used for producing components of voltage on a rest frame, a space vector modulation method is combined to produce appropriate inverter switch signals, and a permanent magnet synchronous motor is further controlled.

The present invention relates to a time sequence SAR (Synthetic Aperture Radar) image classification method on the basis of distribution difference and incremental learning. The time sequence SAR image classification method comprises the selection of incremental samples and the incremental learning of the incremental samples. The time sequence SAR image classification method comprises the steps of: firstly, carrying out change detection on time sequence SAR images by a method based on the distributional difference, utilizing an Egdeworth approach principle to estimate the statistical distribution of the SAS images of a source domain and a target domain, calculating a cross entropy difference index of image distribution, obtaining a change detection image according to a detection threshold acquired by a CFAR (Constant False Alarm Rate) method, and using unchanged regions as incremental samples; and then initializing an SVM (Space Vector Modulation) classifier by utilizing a known training set of the images of the source domain, and completing the incremental learning of an integral incremental sample set and the parameter update of an SVM classification model by the iterative process. The distributional difference change detection method is combined with the incremental learning of a support vector machine and domain self-adaptation from the source domain to the target domain can be completed, so that high-precision classification of the images of the target domain is realized.

An electric power steering assist system for an automotive vehicle comprises a brushless electric motor and a control module for regulating the motor based upon space vector modulation. In response to a steering command, the control module determines a desired quadrature axis current component to provide torque assist in turning the wheels. Also, the control module determines a desired direct axis current component based upon the motor speed such that the desired direct axis current component is zero when the motor speed is less than or equal to the maximum design motor speed, and is negative when the motor speed exceeds the maximum design motor speed. By utilizing a negative direct axis current component, the control module implements a field weakening effect within the motor that allows the motor speed to be temporarily increased greater than the maximum design motor speed to react to rapid steer commands by the operator, such as encountered in evasive maneuvers and the like.

Multilevel converters and space vector modulation operating methods are presented in which fewer than all possible switching states are employed for space vector modulation of rectifier and inverter circuits to promote common mode voltage contribution cancellation or reduction therebetween and by using subsets of possible space vector modulation switching states associated with minimal positive or negative common mode voltages and in some cases using virtual vectors which have zero common mode voltages to eliminate the 3rd order harmonic components in common mode voltage as well as to reduce common mode voltage affects associated with multilevel inverter stages.

The invention discloses a control system for restraining three-phase output voltage of an uninterruptible power supply (UPS) from disequilibrium and harmonic wave. Imbalance output voltage is decomposed to be a positive-sequence component, a negative-sequence component and a zero-sequence component, which pass three groups of PI controllers; the first group of PI controllers primarily controls the output voltage by a proportional controller P under Clarke coordinate to calculate margin of error; the second group of PI controllers adjusts the positive-sequence component by an integral controller I in a positive rotary coordinate system; and the third group of PI controllers restrains the negative sequence by an integral controller in a contra-rotation coordinate system; if the negative sequence is restrained 5 times and the harmonic wave is restrained 7 times, PI control is respectively carried in a reverse 5 times based wave angular velocity rotary coordinate system and a forward 7 times based wave angular velocity rotary coordinate system. Three-phase balance output voltage can be acquired after summing up the output of the five groups of PI controllers, and carrying out the space vector modulation, thus harmonic distortion is greatly reduced.