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180results about How to "Achieve smooth switching" patented technology

Grid connection presynchronization control method of microgrid inverter based on droop control

The invention relates to a grid connection presynchronization control method of a microgrid inverter based on droop control. When the microgrid operates in island, as a voltage source type inverter which functions as the support in the microgrid works in accordance with droop characteristic, a microgrid voltage has a deviation from a high power grid voltage; and the problem of synchronization between the microgrid voltage and the high power grid voltage during the grid connection is the key to realize smooth switchover. The grid connection presynchronization control method provided by the invention comprises the following steps: obtaining frequency and phase position information of the high power grid voltage through a three phase software phase-locked loop (SPLL); carrying out dq (Direct Quadrate) conversion to an output voltage of the inverter based on a power grid voltage phase obtained from the locked phase; subsequently carrying out PI (Physical Impairment) regulation on a q-axis component; overlapping a synchronization angle frequency output by a PI regulator with an angle frequency generated by the droop control to be used as a reference angle frequency of the output voltage of the inverter; and finally realizing the tracking and synchronization of the output voltage of the microgrid inverter to the high power grid voltage through the closed-loop control. The impact current during the grid connection is avoided effectively.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS +1

Trajectory tracking control method and control device for driverless vehicle

The invention relates to a trajectory tracking control method and a control device for a driverless vehicle. The control method comprises that error of present driving trajectory and a reference trajectory of a vehicle is calculated by a data preprocessor, a target performance indicator function which is corresponding to the present driving model is obtained simultaneously; an upper layer controller predicts driving states of the vehicle over a period of time through a vehicle dynamics model; transition switch is conducted to function parameters according to switching control algorithm, and a performance indicator function at present sampling time is obtained; optimal controlled quantity of present time is calculated by considering performance requirement constraint conditions at the same time according to predicted driving states and the performance indicator function; a lower layer controller calculates throttle opening, braking pedal pressure and steering wheel turning angle according to the optimal controlled quantity; and the control device comprises the data preprocessor, the upper layer controller and the lower layer controller. Compared with the prior art, the trajectory tracking control method and the control device for the driverless vehicle have the advantages of being good in control effect, high in practicability, capable of improving stability and safety of vehicles and the like.
Owner:TONGJI UNIV

Double-port stable control method and circuit and bidirectional DC/DC power converter

The invention relates to a double-port stable control method and circuit and a bidirectional DC / DC power converter, and belongs to the technical field of power converters. A controller of the controlcircuit provides a PWM control signal, a driving circuit is controlled to switch on or switch off a corresponding MOS in a switch tube power circuit, and a DC bus voltage VBus in certain stability andprecision is formed between the two ends of a DC bus side capacitor C via a DC bus side filtering circuit. The controller controls the driving circuit by carrying out under-voltage protection of an energy-storage unit when the voltage in the energy storage side is lower than the lower limit of the working voltage; carrying out overvoltage protection of the energy-storage unit when the voltage inthe energy storage side is higher than the upper limit of the working voltage; and limiting the maximal continuous charging / discharging current of the energy-storage unit via an ACM control algorithmwhen the voltage in the energy storage side is within the upper limit and the lower limit of the working voltage. PWM output control is combined with ACM control to realize double-port stable controlof the bidirectional DC / DC power converter, and the method and circuit are suitable for any type of bidirectional DC / DC power converter.
Owner:ANHUI UNIVERSITY OF TECHNOLOGY

Smooth switching control method for three-phase dual-mode inverter

The invention discloses a smooth switching control method for a three-phase dual-mode inverter. The method comprises off-grid and grid-connected smooth switching control and off-grid smooth switching control. Smooth control comprises soft start of virtual impedance and monocycle current feedback control. When the inverter is switched to the grid-connected mode from the off-grid mode, output current phase lead control and smooth switching control are conducted, temporary impact of output currents and in-network currents of the inverter are restrained, and then backward flowing of energy of the inverter is greatly reduced, and grid-connected smooth switching is achieved. When the inverter is switched to the off-grid mode from the grid-connected mode, only monocycle current feedback control is conducted, the in-network currents are reduced to zero quickly, DC side voltage fluctuation of the inverter caused by temporary unbalance of the currents is avoided, and off-grid smooth switching is achieved. According to the method, the problems that current impact is large when the micro-grid inverter is connected to the grid and DC side voltage fluctuates when the inverter is off-grid are solved, and smooth switching of the operation modes of the micro-grid is achieved.
Owner:ZHANGZHOU KEHUA TECH CO LTD

Wide-input direct current inverter topology and feedforward average current control method thereof

InactiveCN106169868AImprove input dynamic response performanceGood input dynamic response performanceEfficient power electronics conversionDc-dc conversionAverage currentInverter topology
The invention belongs to the technical field of power electronic application, and especially relates to a wide-input direct current inverter topology and a feedforward average current control method thereof. The wide-input direct current inverter topology comprises a two-transistor Buck-Boost inverter and an interleaved two-transistor Buck-Boost inverter. The feedforward average current control method applicable to the wide-input direct current inverter topology is composed of an input voltage feedforward module, a mode switching module, a voltage outer ring and a current inner ring. According to the method, input voltage feedforward is introduced into the current inner ring in average current control, a feedforward function from the input voltage feedforward to the current inner ring is computed, simplification is carried out, thereby obtaining feedforward average current control applicable to practical application, and the input dynamic response performance of the inverters in a whole input voltage range is greatly improved; and moreover, by adoption of an interleaving technology, the conversion capacity is increased, the output current ripple is effectively reduced, and the support is provided for the field with wide range input and high power conversion.
Owner:NORTH CHINA ELECTRIC POWER UNIV (BAODING) +1

Inverse multi-solution selection and time optimal trajectory planning algorithm of mechanical arm

The invention relates to the field of mechanical arms of foot type robots, in particular to an inverse multi-solution selection and time optimal trajectory planning algorithm of a mechanical arm. According to the algorithm, the most appropriate group of solutions can be rapidly selected from multiple inverse solutions according to the current pose of the mechanical arm, so that singular patterns are effectively avoided, smooth switching between different inverse solutions is achieved, and continuity and non-oscillation of control and action of the mechanical arm are guaranteed; and a trajectory with optimal time is planned by using a trajectory planning method combining a heptatic polynomial and conditional proportional control, so that smooth, continuous and derivable joint angles, angular velocities, angular accelerations and angular jerk are ensured; and meanwhile, multi-target and multi-constraint conditions are met, and the specification of an actuator is met; and the constraint condition comprise joint angular velocity maximum value constraint or joint angular acceleration maximum value constraint, and the like. According to the algorithm, the calculation amount of multi-solution selection and trajectory planning is greatly reduced, real-time and efficient time optimal trajectory planning can be realized, and the algorithm can be popularized and applied to a low-calculation-power controller.
Owner:BEIJING JIAOTONG UNIV

Distributed-generation three-phase inverter smooth switch control method

The invention discloses a distributed-generation three-phase inverter smooth switch control method. The method includes smooth switch control over two parts from isolated island operation to grid-connected operation and from the grid-connected operation to the isolated island operation. A smooth switch control link is mainly composed of a phase-locked loop (PLL) and a switch. When an inverter is switched from the isolated island operation to the grid-connected operation, output voltage of the inverter is subjected to presynchronization by operating the switch, so that the output voltage and grid voltage of the inverter are synchronized, current impacting during grid connection is reduced, and smooth grid connection switch is realized; when the inverter is switched from the grid-connected operation to the isolated island operation, reference instruction controlled by current are gradually decreased to zero form current instruction current by operating the switch, off-grid operations have no effect on a system since the grid-connection current is dropped to zero before disconnection of the grid connection switch, the output voltage of the inverter cannot fluctuate, and off-grid smooth switch is realized. With the method, dual-mode smooth switch operation of the distributed generation system is realized.
Owner:HUNAN UNIV

Control method for smooth handoff of micro grid operation mode based on DG ad-hoc network strategy

The invention discloses a control method for smooth handoff of a micro grid operation mode based on a DG ad-hoc network strategy, which comprises the following steps: when the operation mode of the micro grid is changed from a grid-connected mode into an isolated island operation mode, according to the condition that whether a distributed power source DG can perform isolated island operation, the micro grid is split into a plurality of DG local ad-hoc networks capable of performing independent operation, and continue power supply to the important load or the local load is ensured through the DG local ad-hoc networks; after each DG local ad-hoc network is stabilized, outward search is performed and the power supply range is enlarged, so that DG dynamic ad-hoc networks are formed; after all the DG dynamic ad-hoc networks are stabilized, the DG dynamic ad-hoc networks which satisfy interconnection requirements are sequentially subjected to network interconnection for operation by taking the DG dynamic ad-hoc network including a micro grid main power source as the center; after power supply of a public power distribution network recovers, all the DG dynamic ad-hoc networks are grid-connected with the public power distribution network for operation. According to the control method, the DG local ad-hoc networks ensure the continue power supply to the important load of the micro grid; the power supply is recovered to power-losing areas continuously through the DG dynamic ad-hoc networks, favorable conditions are provided for the operation mode, which is changed from the isolated island operation mode into the grid-connection operation mode, of the micro grid, and the smooth hand-off of the micro grid operation mode is ensured.
Owner:CHINA ENERGY ENG GRP GUANGDONG ELECTRIC POWER DESIGN INST CO LTD

Aircraft global finite time neural network control method based on switching mechanism

The present invention relates to an aircraft global finite time neural network control method based on a switching mechanism, belonging to the field of aircraft control. The problem of aircraft globalfinite time neural network control is solved. The method comprises the steps of: decoupling an aircraft vertical model to a height subsystem and a speed subsystem, employing backstepping control forthe height subsystem, and employing PID control for the speed subsystem. For the height subsystem, a switching mechanism is introduced to achieve switching between an effective approaching intra-areaneural network control and approaching outer-area robust control, and based on the tracking errors and the modeling errors, performing updating of the neural network weight so as to improve the learning performance of the neural network, and giving a robust design scheme on this basis, achieving finite time convergence of the tracking errors of the system. The aircraft global finite time neural network control method ensures that the aircraft neural network control is still worked in the effective approaching area to achieve the global stability of the closed-loop system and ensure the performance demand of the practical engineering application.
Owner:NORTHWESTERN POLYTECHNICAL UNIV

Control apparatus and control method for maintaining stable voltage of conflux DC bus in distributed power generation system

The invention provides a control apparatus and control method for maintaining stable voltage of a conflux DC bus in a distributed power generation system. In order to enable the current transformers of multiple power generation devices to realize parallel operation under the condition that there is no interconnection line communication, voltage instruction signals are obtained through calculation according to a preset sagging characteristic by actual output currents, current instruction signals are given according to actual conditions by an MPPT algorithm or a system, two control signals obtained through operation of a voltage control loop and a current control loop are sent to the minimum taking link of CPU control software, and the output of the link is used for PWM to ensure no overvoltage in case of a current control mode and ensure no overcurrent in case of a voltage control mode, such that smooth switching of multiple electric power converting devices between the current control mode and the voltage control mode is realized, and under the condition that there are no interconnection communication lines, multiple converters can realize stable parallel output according to power which can be obtained by themselves.
Owner:HARBIN ENG UNIV

Off-grid and grid-connected smooth switching method of virtual synchronous generator

The invention provides an off-grid and grid-connected smooth switching method of a virtual synchronous generator. The smooth switching method is characterized by comprising grid-connected/off-grid and off-grid/grid-connected smooth switching. As for off-grid/grid-connected switching, the switching strategy is added in the off-grid and grid-connected switching process without modifying the control strategy of the virtual synchronous generator, and the reference voltage of the virtual synchronous generator is changed into the command reference voltage from the grid voltage and the correction angular velocity of pre-synchronous control is enabled to be zero directly so as to realize grid-connected/off-grid smooth switching. Popularization of the virtual synchronous generator technology is further facilitated in the field of new energy power generation, and friendly accessing of distributed energy resources can be realized so as to enhance the stability of the electric power system. Besides, application of the control strategy and the theoretical analysis method related to the conventional synchronous generator to VSG is facilitated so as to play an important role in the active power distribution network and the microgrid in the future.
Owner:STATE GRID QINGHAI ELECTRIC POWER +2

Starting method for brushless direct-current excitation synchronous motor

The invention discloses a starting method for a brushless direct-current excitation synchronous motor. The method includes the following steps of: S1, asynchronous starting closed-loop vector control process: three-phase reference voltage Va, Vb and Vc can be obtained according to three-phase stator current Ia, Ib and Ic of the synchronous motor, and the three-phase reference voltage Va, Vb and Vc c are subjected to pulse-width modulation and are outputted to stator windings of the synchronous motor so as to perform excitation; S2: transition closed-loop vector control process: when the rotation speed of the synchronous motor achieves preset rotation speed, excitation provided by the stator windings is gradually switched to excitation provided by a brushless direct-current excitation device; and S3: synchronous closed-loop control process: when all excitation is switched to excitation provided by the brushless direct-current excitation device, the synchronous motor enters a synchronous operation process. The starting method for the brushless direct-current excitation synchronous motor of the invention has the advantages of simple control, low starting current, excellent speed adjusting performance and high starting torque.
Owner:ZHUZHOU NAT ENG RES CENT OF CONVERTERS

Control method and device of permanent magnet synchronous motor sensorless for electromobile EHPS

The invention relates to a sensorless control method and device of a permanent magnet synchronous motor of an electromobile EHPS (electric hydraulic power steering system). The control method dependson a permanent magnet synchronous motor DC/AC controller; for a demand of the electromobile EHPS, the controller realizes real-time estimation on the rotor location and speed of the permanent magnet synchronous motor by utilizing the control method of the multi-algorithm fused sensorless, thereby realizing the reliable control on the permanent magnet synchronous motor full rotating speed range ofthe EHPS; the controller can realize the current voltage detection, the external communication, high-voltage inversion and like functions, and external interfaces with high-low voltage supply, AC output, enabling signal and communication line; the controller is conducive to an assisting motor for the EHPS without installing a sensor, the system cost can be reduced, the system complexity is lowered, and the system reliability is improved. Furthermore, the controller can properly reduce the power-assisted steering when the vehicle speed is high, the road feel is improved, and the driving stability of the vehicle is improved.
Owner:BIT HUACHUANG ELECTRIC VEHICLE TECH

Dual three-phase motor minimum harmonic injection over-modulation strategy and carrier wave realization method thereof

The invention discloses a dual three-phase motor minimum harmonic injection over-modulation strategy and a carrier wave realization method thereof. The specific method comprises the steps of introducing the concept of a middle vector, performing analysis on a harmonic voltage which needs to be injected into an over-modulation region harmonic sub plane based on a space voltage vector algorithm, andproposing a minimum harmonic injection strategy of the dual three-phase motor over-modulation region, so that the harmonic current in the over-modulation region is reduced to the maximum degree; andspecific to the problems of asymmetrical pulse width modulation waveform, relatively high switching loss and the like of the six-phase inverter four-vector space voltage vector algorithm, a linear modulation region algorithm and an over-modulation region algorithm are unified into a carrier wave-based dual zero sequence injection pulse width modulation strategy to be realized, so that smooth switching between the linear modulation region and the over-modulation region can be realized. The problems of blank of the minimum harmonic injection technology and a complex SVPWM-based realization process in the prior art are solved.
Owner:XIAN UNIV OF TECH

Current feed forward-voltage feedback flux weakening control method for electromobile permanent magnet synchronous motor

The invention discloses a current feed forward-voltage feedback flux weakening control method for an electromobile permanent magnet synchronous motor. The current signals of the built-in electromobilepermanent magnet synchronous motor are collected, and the conversion of coordinates is carried out to obtain stator current direct-axis component and stator current quadrature-axis component; voltagesignals are collected to obtain voltage source inverter direct current bus voltage; rotary transformer signals on the built-in permanent magnet synchronous motor are collected, and the rotor positionangle and mechanical rotating speed of the motor are obtained through calculation; and a blurry PI feedback link is added on the basis of a traditional formula computing method. For the purpose thatthe motor is smoothly and stably switched in a constant torque region and a constant power region, a smooth switching method based on a weighting function is proposed. The method disclosed by the invention is simple and practicable, the dynamic performance of the motor in the constant power region can be improved effectively, the method has relatively high parameter robustness, and the method canbe smoothly and stably switched in the constant torque region and the constant power region.
Owner:TIANJIN POLYTECHNIC UNIV
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