Measurement, Control, and Automation

A Single-Stage Neutral Point Clamp Inverter with Reduced Voltage Stresses on Power Elements

2021-07-15T08:40:09+00:00

In this paper, a topology incorporating the DC-link type quasi-switch boost network with the traditional three-level neutral point clamped inverter is presented. The third harmonic injection method is proposed to provide some benefits such as: enhancing the modulation index or improving the voltage gain. Moreover, the stress voltage on power devices like capacitors, diodes, and switches is decreased significantly. The mathematic analysis is detailed to produce the equations output voltage for the proposed converter. The comparison between the proposed topology to conventional quasi-switch boost neutral point clamped inverter topology is carried out. Simulation and experimental results are conducted to verify the accuracy of inverter operating theory.

Simple balancing method for unbalanced dual-bridge converters based on fundamental harmonics approximation and trigonometric calculation

2022-03-07T04:45:31+00:00

Three-phase Dual-Active-Bridge converters use a three-phase transformer for isolation and voltage leveling. Due to fabrication, the inductance in the transmission path of each phase may be different from each other. If the difference is large enough, the current may be unevenly distributed among phases that lead to the unbalance in loss and heat distribution of power switches and transformers. This paper proposes a simple current balancing method among phases for three-phase Dual-Active-Bridge converters due to inductance mismatch in the transmission path. The method is based on first harmonic approximation and trigonometric calculation of the phase shift for each phase. Simulation and experimental results show that the proposed method can help balance the phase current effectively.

T-type based Grid-Side Converter Control Design of Double Fed Induction Generator – A practical approach

2022-02-18T08:37:56+00:00

In this paper, the control design for the grid-connected converter used as a part of the wind turbine generator is discussed. First, the three-phase T-type multilevel converter, which exhibits several advantages such as low total harmonic distortion, reduced voltage stress, and switching loss, is employed for the power stage. Second, finite control set model predictive control (FCS-MPC) is adopted to achieve a multi-objective optimization solution for the inner grid-connected current control loop. This approach not only allows the current to quickly track its desired value but also minimizes the capacitor voltage balance and the switching loss. Finally, a practical approach is proposed to design the Fuzzy-based PI controller for the DC bus voltage regulation. The design procedure is straightforward, and only requires several known information getting from the converter. Specifically, the proposed controller allows users to exactly restrict the inrush current, as well as minimize the overshoot of the DC bus voltage during startup. The effectiveness of the proposed control strategy is verified by numerical simulations. In which all controlled algorithms are implemented by standard C language such that the consistency between simulations and future practical implementations is guaranteed.

Modeling of Axial Flux Permanent Magnet Motors by a Finite Element Ap-proach-Application to In-wheel Motorcycles

2022-01-12T04:07:52+00:00

Axial flux permanent magnet motors have been applied for many electric vehicles due to the high torque and power densities, compact sizes, and multipolar disc-type structure. In this paper, the axial flux permanent magnet motor with the concentrated winding, and axial flux-segmental rotor is presented and compared with a conventional BLDC motor. The proposed topology consists of permanent magnet segments and a slotted stator. The comparison with the existing BLDC motors, the proposed machine contains the reduced amount of permanent magnets and being easy to scale up power and torque. This approach makes the assembly easier and reduce the cost compared to conventional motors. Moreover, the multi sector-proposed topologies have the higher torque density and torque-to-weight ratio compared to reported the axial flux switch reluctance motors. The detailed design and operation of the proposed machine are presented, and the performance is also evaluated for an in-wheel traction application. Especially, for a multipolar disc-type structure, the axial flux permanent magnet motors is easy to scale up power for the next models.

Phát triển công thức từ thế véc tơ bằng kỹ thuật liên kết một chiều các bài toán con - Ứng dụng cho bài toán từ động với cấu trúc vỏ mỏng

2022-01-31T10:07:47+00:00

Modeling of magnetodynamic problems always exists and plays an important role in the fields of electrical systems in general and electrical equipments in particular. It can be considered as a spine problems decided to the working process of the electrical systems and devices. Hence, the analysis, computation and simulation of physic phenomena, electromagnetic processes of the magnetodynamic problems is really an important topic concerning for researchers in Viet Nam and in the world as well. In this study, a magnetic vector potential formulation is developed by one way-coupling subproblem technique to calculate field quantities (magnetic field density, eddy current density, joule power loss) existing and occuring in the thin shell structures neglecting edge and corner effects. The development of the method will be verified to be applied to the real problem “TEAM problem 21, model B).

Studying the influence of steel arrangements on magnetic flux density distributions in core blocks of the shunt reactors via a finite element method

2021-07-29T09:38:12+00:00

The shunt reactor is used to absorb excess reactive powers generated by capacitive powers on the lines for no-load or low-load operations, balance of reactive powers in electrical systems, avoiding the overvoltage at the line end and maintaining the voltage stability at the
specified level. The shunt reactor is designed with air gaps in the iron core to increase reluctances, to reduce the magnetic flux and to avoid the saturation of the magnetic circuit. However, the fringing flux always appears and exist arround air gaps. This component
orients from this core block to another that is suitable to the direction of laminations with different angles, making influence to the shunt reactor parameters, where appearing the fringing flux around the iron core blocks, leading to uneven distribution of the mangetic flux in the iron cores. In this paper, a finite element method is applied to investigate different types of lamination matching, cutting the bevel around the iron cores to avoid saturation of the magnetic circuit existing in the edge corner of the steel sheets. Through the obtained
results, the paper proposes a suitable coupling type for the core blocks of shunt reactors applied in high and supper-high voltage systems in Vietnam.

Mô Hình Hóa Ổ Từ Dọc Trục Hình C Cấu Tạo Nguyên Khối

2022-02-11T03:54:31+00:00

Dòng điện xoáy được tạo ra trong cơ cấu chấp hành ổ đỡ từ dọc trục cấu tạo nguyên khối bởi từ trường thay đổi theo thời gian. Do đó ảnh hưởng lớn đến động lực học và thiết kế điều khiển hệ thống ổ từ cấu tạo nguyên khối. Trong bài báo này công thức gần đúng của từ trở hiệu dụng phần tử không khí được đưa ra sát với công thức ban đầu, từ đó đưa ra mô hình toán học chính xác hơn. Đặc biệt tác giả đã đưa ra được mô hình động lực học phi tuyến trên miền thời gian của ổ từ cấu tạo nguyên khối.

Optimization of robotic arm trajectory using genetic algorithm in cosideration of robot controller

2022-03-10T06:43:43+00:00

One of the main problems in robotic is optimized trajectory planning. The planned trajectory must be optimized in moving time while satisfies motor torque and velocity and position constraints. This paper presents the design of optimized trajectory using genetic algorithm. Diffrent from other researché that calculate controlled torques from inverese dynamics of the robot, this paper calculates the controller torques from controller outputs. This proposed calcuation guarantees the similarity between design and implemetation processes. Simulations have been done to verify the effectveness of the proposed approach.

Improving the YOLO v4 algorithm applied to the powdery mildew and downy mildew monitor system on cucumber plants

2021-09-01T02:05:50+00:00

The technology of artificial intelligence, robotics, and IoT is developing very strongly. The application of these technologies to serve in agricultural production is very necessary to reduce labor and increase crop productivity. Monitoring and warning crop diseases promptly will help to treat diseases faster, save financial resources and increase crop yields. By combining artificial intelligence algorithm with automatic data acquisition and information transmission system, we have designed a robot to monitor and warn against powdery mildew and downy mildew on the cucumber plants. Our improved YOLO v4-tiny algorithm gave an accuracy of 83.26% which is 0.22% higher than the original YOLO v4-tiny version; the system initially tested with Raspberry PI and Camera PI 5MB hardware gave good results. The system will continue to study to upgrade the hardware, as well as add the dataset so that it can be put into cucumber production in the net house.

Design of Backstepping-Sliding mode control for two–mass systems

2021-11-08T06:58:36+00:00

The paper presents the results of backstepping - sliding mode control based on control design for speed actual value of load motor match speed reference for two-mass systems. This controller is combined with an extended state observer (ESO) for estimating the system variables (torque and speed at motor and load sides) of two-mass systems. The effectiveness of the control systems is compared with the PI controller. The results of analysis and evaluation between the speed control methods for the two-mass system were performed by Matlab simulation software.