This work proposes and experimentally verifies a novel virtual flux (VF) estimation method for the predictive control of back-to-back voltage-source power converters with a space vector modulator (SVM). The novelty of the proposed approach is the development of a time domain initial bias compensation virtual flux (IBC-VF) estimation method and its combination with a predictive control scheme with constant switching frequency. Theoretical analysis and implementation procedures of the proposed method are developed in detail. Compared to two conventional bandpass filter-based VF estimation methods, the proposed IBC-VF method shows a much faster dynamic response. The whole IBC-VF-based predictive control scheme is realized in the $\alpha\beta$ frame and so does not require Park's transformation. The proposed control scheme is implemented on a commercial off-the-shelf field-programmable-gate-array-based platform. By using a single-cycle timed loop (SCTL) technique, the whole computation is finished within 2.6 $\mu\hbox{s} $ , making the compensation of the calculation time obsolete. Both simulation and experimental results emphasize the effectiveness of the proposed scheme.

Predictive Control With Novel Virtual-Flux Estimation for Back-to-Back Power Converters

Three-Phase Voltage Source Converters (VSCs) are finding widespread applications in grid integrated power conversion systems. The control systems of such VSCs are in an increasing number of these a ...

Control of Grid Integrated Voltage Source Converters under Unbalanced Conditions : Development of an On-line Frequency-adaptive Virtual Flux-based Approach

MODELING AND CONTROL OF A DOUBLY-FED INDUCTION GENERATOR FOR WIND TURBINE-GENERATOR SYSTEMS Xin Jing, M.S.E.E Marquette University, 2012 Wind energy plays an increasingly important role in the world because it is friendly to the environment. During the last decades, the concept of a variable-speed wind turbine (WT) has been receiving increasing attention due to the fact that it is more controllable and efficient, and has good power quality. As the demand of controllability of variable speed WTs increases, it is therefore important and necessary to investigate the modeling for wind turbine-generator systems (WTGS) that are capable of accurately simulating the behavior of each component in the WTGS. Therefore, this thesis will provide detailed models of a grid-connected wind turbine system equipped with a doubly-fed induction generator (DFIG), which includes the aerodynamic models of the wind turbine, the models of the mechanical transmission system, the DFIG models and the three-phase two-level PWM voltage source converter models. In order to obtain satisfying output power from the WTGS, control strategies are also necessary to be developed based on the previously obtained WTGS models. These control schemes include the grid-side converter control, the generator-side converter control, the maximum power point tracking control and the pitch angle control. The grid-side converter controller is used to keep the DC-link voltage constant and yield a unity power factor looking into the WTGS from the grid-side. The generator-side converter controller has the ability of regulating the torque, active power and reactive power. The maximum power point tracking control is used to provide the reference values for the active power at the stator terminals. The pitch angle control scheme is used to regulate the pitch angle and thus keep the output power at rated value even when the wind speed experiences gusts. Various studies in the literature have reported that two-level converters have several disadvantages compared with three-level converters. Among the disadvantages are high switching losses, high dv/dt, and high total harmonic distortion (THD). Hence, the models and field oriented control schemes for three-level neutral-point-clamped (NPC) converters are also investigated and applied to a WTGS. Besides, an advanced modulation technology, namely, space vector PWM (SVPWM), is also investigated and compared to traditional sinusoidal PWM in a WTGS.

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Modeling and control of a doubly-fed induction generator for wind turbine-generator systems

The invention discloses a fault handling platform system and a fault handling method. The fault handling platform system comprises: a fault collection module which is connected with at least one intelligent terminal and is used for collecting the fault information reported by the at least one intelligent terminal, a fault analysis module which is connected with the fault collection module and is used for analyzing the first fault information reported by a first intelligent terminal in the at least one intelligent terminal and determining a first fault handling solution corresponding to the first fault information, and a fault data access module which is connected with the fault analysis module and is used for sending the first fault handling solution to at least one set of electronic equipment. Through the solution, the technical problem that an error can be made easily when a fault occurring in the intelligent terminal is handled by a manual service in the prior art is solved.

Fault handling platform system and fault handling method

The invention discloses an energy-saving device for an escalator. The energy-saving device comprises an ascending escalator transmission chain and a descending escalator transmission chain and further comprises an energy recycling transmission chain. One end of the energy recycling transmission chain is connected with the descending escalator transmission chain while the other end of the energy recycling transmission chain is connected with the ascending escalator transmission chain. A heavy block hydraulic energy storage device is located in the middle part of the device. The energy recycling transmission chain converts gravitational potential energy of a crowd on a descending escalator body into hydraulic energy and stores the hydraulic energy in the hydraulic energy storage device. The hydraulic energy storage device then releases the hydraulic energy and the hydraulic energy is converted into kinetic energy through a hydraulic motor connected with the hydraulic energy storage device. In this way, an ascending escalator body is driven to do the continuous motion. Namely, the gravitational potential energy of the crowd on the descending escalator body is recycled. In addition, energy consumption can be effectively reduced and effective work load of the descending escalator body is increased and drive load carrying capacity of the ascending escalator body is improved. The energy-saving device is high in gravitational potential energy recycling capability and efficient in output.

Energy-saving device for escalator

This paper presents a novel decoupling control strategy for three-level NPC PWM rectifier without line voltage sensors, combining virtual flux oriented control (VOFC) with traditional direct current control based on the decoupled d-q frame. A virtual flux linkage vector can be constructed similarly to the observation of AC motor flux linkage, which may serve as the oriented vector in the vector control of the PWM rectifier instead of the line voltage vector. As a result, the AC voltage sensors and phase locked circuit will be eliminated and the costs of PWM rectifier can be reduced. According to the design principle of AC motor flux observer, a modified virtual grid flux observer and the grid voltage estimation method are proposed, which solves the DC drift problem caused by a wrong initial value selecting of integer in virtual flux oriented vector control for PWM rectifier. Finally based on Matlab/Simulink, this paper constructs virtual flux oriented current decoupling control simulation model of three-level PWM rectifier without grid voltage sensor. The reliability of the observer has been proved. The good dynamic and static performances of the control scheme have been showed by simulation.

Study of the Control System of Three-Level PWM Rectifier Based on Virtual Flux Oriented

The invention relates to an intelligent drive control system of an escalator, which is characterized by comprising a group control main computer, a main control computer, a sensor and a plurality of actuators. The main control computer is respectively connected with the actuators and the sensor, the actuators comprise a drive host, a brake, an electromagnetic clutch and are respectively connected with the main control computer, and the main control computer is also connected with the group control main computer. The intelligent drive control system also comprises an LED (light-emitting diode) display, and the LED display is connected with the main control computer. By adopting the system, the number of the used drive hosts can be adjusted according to the load on the escalator, and the energy-saving purpose can be fully realized.

Intelligent drive control system of escalator

A large-height escalator energy-saving main unit comprises a motor (6), an electromagnetic brake (7) and a speed reducer (8). The motor (6) and the speed reducer (8) are connected by a brake disk with a coupler inside, and the brake disk is braked by the electromagnetic brake (7). The large-height escalator energy-saving main unit is characterized by further comprising an electromagnetic clutch (1), reflective photoelectric sensors (4), an auxiliary support (2) with a mandrel, and a sprocket (3) arranged on a driven disk of the electromagnetic clutch (1), the auxiliary support (2) with the mandrel is used for supporting a driving disk and the driven disk of the electromagnetic clutch (1), all of the motor (6), the speed reducer (8), the reflective photoelectric sensors (4), the electromagnetic clutch (1) and the auxiliary support (2) with the mandrel are mounted on an escalator, commands of a control system are executed by a cable, and the reflective photoelectric sensors (4) are respectively arranged at detection positions of the driving disk and the driven disk of the electromagnetic clutch (1). The sensors are adopted to monitor the operating state of the electromagnetic clutch (1), reliable joint of the electromagnetic clutch (1) is ensured when the system is operated, and the escalator is more stable and reliable in running.

Large-height escalator energy-saving main unit

The invention relates to an energy-saving host of a high escalator, which comprises a motor (6), an electromagnetic brake (7) and a speed reducer (8). The motor (6) and the speed reducer (8) are connected through a brake disc with an internal coupling and are used for stopping the brake disc through the electromagnetic brake (7). The energy-saving host of the high escalator is characterized by also comprising an electromagnetic clutch (1), a reflective photoelectric sensor (4), an auxiliary support (2) with a core shaft and a sprocket wheel (3), the sprocket wheel (3) is arranged on the driven disc of the electromagnetic clutch (1), the auxiliary support (2) with the core shaft is used for supporting the drive disc and the driven disc of the electromagnetic clutch (1), the motor (6), the speed reducer (8), the reflective photoelectric sensor (4), the electromagnetic clutch (1) and the auxiliary support (2) with the core shaft are all arranged on the escalator, commands of a control system are implemented through cables, and the reflective photoelectric sensor (4) is respectively arranged in the detection positions of the drive disc and the driven disc of the electromagnetic clutch (1). Since the working status of the electromagnetic clutch (1) can be monitored through the sensor, reliable connection of the electromagnetic clutch (1) can be ensured during operation of the system, and the escalator can work more stably and reliably.

Energy-saving host of high escalator

The utility model relates to an intelligent driving control system for an escalator The intelligent driving control system for the escalator is characterized in that a group control host computer, a main control computer, sensors and an actuating mechanism are included, wherein the main control computer is connected with the actuating mechanism and the sensors respectively; the actuating mechanism comprises driving hosts, brakes and an electromagnetic clutch which are connected with the main control computer respectively; and the main control computer is also connected with the group control host computer The intelligent driving control system for the escalator also comprises an LED display screen, and the LED display screen is connected with the main control computer The system has the advantage that the number of the driving hosts can be adjusted according to the load of the escalator, so as to fully realize the purpose of energy conservation

Chonghui Song

Papers

Study of the Control System of Three-Level PWM Rectifier Based on Virtual Flux Oriented

Intelligent drive control system of escalator

Large-height escalator energy-saving main unit

Energy-saving host of high escalator

Intelligent driving control system for escalator