No. 3 (2022)

Article

• Research on assessment of power loss and performance of SiC MOSFET three-phase diode-clamped inverter

  PHẠM THỊ MỘNG TUYỀN, NGUYỄN PHƯỚC LỘC, TRẦN NGỌC THOA, PHẠM THỊ KIM THỂ (Author)

  Abstract | PDF (Vietnamese) | Views: 4 Downloads: 10

  This paper presents the power loss and performance analysis of a three-level inverter (3L-NPC). Calculation of power loss on SiC 3L-NPC semiconductor devices using carrier modulation (PD_PWM) technique. The above structure is modeled on PLECS simulation software to determine the total loss and performance of the SiC 3L-NPC inverter. The simulation results are analyzed, evaluated, and compared with the Si IGBT 3L-NPC structure using traditional IGBT semiconductors. Furthermore, SiC MOSFETs are used to achieve system performance at high switching frequencies. The results will verify the features of the SiC 3L-NPC inverter, the respective modulation techniques used, and their effect on reducing and improving the power loss in the inverter using SiC technology semiconductor.

• Design of rooftop solar power monitoring system

  LÊ NHỰT KÝ, NGUYỄN PHÚC KHẢI, NGUYỄN NGỌC TUẤN (Author)

  Abstract | PDF (Vietnamese) | Views: 2 Downloads: 5

  This paper presents an independent remote monitoring and data acquisition system independent of the inverter to monitor a solar power (PV) system. The monitoring system is built on the SCADA architecture of the Internet of Things (IoT). The system uses the Modbus RTU industrial transmission network to transmit the collected data from the sensor to the Raspberry Pi embedded computer and process the data using the Node-RED programming tool. Collected data will be stored on a local MySQL server created by Raspberry Pi and managed by web phpMyAdmin. The values of current, voltage, capacity, frequency, power factor, etc. will be displayed on the monitoring interface of Node-Red Dashboards. Experimental results show that this study can be applied in practice and has the ability to scale up to monitor multiple solar power systems at the same time. 

   

• The construction of motion equation of the guide wheel according to the caster angle

  TRẦN HOÀNG XUÂN THẮNG, NGUYỄN THÁI VÂN, NGUYỄN ĐỖ HOÀI PHONG, CHÂU TRUNG TÍNH (Author)

  Abstract | PDF (Vietnamese) | Views: 4 Downloads: 11

  The angles of wheel placement greatly affect the motion stability and dynamics of the car. This paper presents a method to determine the differential equation describing the motion of the guide wheel with its tilt angle of vertical cylinder in longitudinal plane (the caster angle). The research objective is to establish the differential equation system of the guide wheel motion to serve the investigation of dynamic factors, as a premise for the investigation to find the optimal tilt angle value (optimal caster angle), to propose solutions to design a suspension system with a caster angle that adapts to the car's load and speed when operating in order to ensure the car's motion dynamics and stability. 

• Field oriented control for the permanent magnet synchronous motor using NPC 3-level inverter

  LÊ TRUNG HIẾU, BÙI THANH HIẾU, NGUYỄN VĂN NHỜ (Author)

  Abstract | PDF (Vietnamese) | Views: 2 Downloads: 12

  This paper presents the field oriented control (FOC) technique for the permanent magnet synchronous motor (PMSM) using NPC 3-level inverter: (1) Application of the technique of field oriented control into PMSM motor control delivers good control quality, quick response; (2) Using NPC 3-level diode-clamped inverter as a source of culture offers significant advantages such as higher performance, higher voltage usage, and minimal switching frequency. Permanent magnet synchronous motor math model, field oriented control technique, NPC 3-level inverter are specifically presented in the article. Simulation and survey results are performed using Matlab/Simulink software. 

   

• A survey on the oscillation of Tesla Model 3 electric cars by 3D oscillation dynamics model

  NGUYỄN THÀNH TRƯỜNG GIANG, CAO HÙNG PHI, KHẨU TẤN PHÁT (Author)

  Abstract | PDF (Vietnamese) | Views: 3 Downloads: 9

  This paper presents the survey results of the oscillation of Tesla Model 3 electric cars when traveling on the ISO 8608:2016 standard C road with different speeds. The main method used is the Newton Euler structure separation method to establish the system of car dynamics equations by the 3D oscillation model. The setup equations are simulated using MATLAB-Simulink software to investigate the oscillation of Tesla Model 3 electric cars. The survey results show that with a speed range from 60 to 80 km/h, the car moves within the limits of human working capacity with the C pavement type according to ISO 8608:2016 standard. 

   

• Research on optimization of the extraction Procedure of secondary metabolites from blue pea flower (clitoria ternatea l.) using the response Surface methodology - central composite design

  TRƯƠNG VĂN XẠ, NGUYỄN THỊ HUỲNH NHƯ, BÙI XUÂN TIẾN, TRẦN KIM THOA (Author)

  Abstract | PDF (Vietnamese) | Views: 4 Downloads: 4

  Blue pea flower (Clitoria ternatea L.) is a medicinal plant containing many secondary metabolites that help prevent and treat diseases. This study aims at identifying the optimal values of different factors directly influencing the polyphenols, flavonoids, and alkaloids: ethanol concentration, liquid/solid ratio, extraction duration. These three factors were subsequently optimized using the response surface methodology - central composite design. Results showed that total polyphenol, total flavonoid have the most optimal 60% ethanol, 1:1 liquid/solid ratio and the extraction time of 96 hours and 48 hours, respectively. Total alkaloids have the most optimal 60% ethanol, 2:1 liquid/solid ratio and the extraction time of 96 hours. In optimized, total polyphenols 270,308 μg GAE/ml extract, total flavonoids 331,410 μg QE /ml extract and total alkaloids 39,118 μg AE/ml extract. Blue pea flower can be used as a material source in extracting secondary metabolites which contain antioxidant activity..

• Optimizing the placement of reactive power compensation devices on the power grid using the marine predators algorithm (MPA)

  NGUYỄN MINH ĐẠT, NGUYỄN PHÚC KHẢI (Author)

  Abstract | PDF (Vietnamese) | Views: 5 Downloads: 7

  his article presents a meta-heuristic method for optimizing the placement of reactive power compensation devices in the power grid using the Marine Predators Algorithm (MPA). The article makes a simulation to optimize the installation location of reactive power compensation devices on the power grids up to 57 buses using the Matlab software. The objective function of the problem is a multi-objective function with the technical objectives such as minimizing power loss, minimizing voltage deviation, and the economic objectives such as minimizing the investment cost of compensating equipment. The problem lso considers common operating conditions on the existing power grid, such as voltage limitations at load buses and transmission capacity limitations of the grid. The Marine Predators Algorithm is used to solve the problem for the standard IEEE 30-bus and 57- bus systems, and compare the optimal calculation results with published methods in the literature. With a medium-sized grid, such as the IEEE 30-bus and 57-bus systems, the results of the MPA algorithm in both grids are more efficient, have a smaller average value of the optimal function, and the faster convergence process compared to the improved Moth- flame Optimization and Moth-flame Optimization methods. The load voltage is always guaranteed to be within the allowable limit and closer to the set value. The calculation results show that the MPA method can resolve problems for large-scale power grids. 

   

• Difficulties faced by students in speaking English at Vinh Long University of Technology Education

  LÊ VĂN ĐIỆP, PHẠM MINH TRUNG (Author)

  Abstract | PDF (Vietnamese) | Views: 5 Downloads: 12

  English is becoming an important or, in other words, indispensable tool in international communication today as this language is extensively used in various aspects of life ranging from education, health care, business, engineering and so on. In this context, English speaking skill is emphasized and prioritized in both teaching and learning at most universities, and Vinh Long University of Technology Education (VLUTE) is not an exception. As a matter of fact, university students in general and VLUTE students in particular have to deal with a certain number of obstacles in learning English speaking skill and many of them have started to fear speaking classes. This article identifies the difficulties faced by VLUTE students in learning English speaking skill and proposes suggestions to assist them in overcoming those difficulties. The findings were achieved with the use of an adapted questionnaire to collect VLUTE students' opinions on their difficulties in English speaking sessions and several suggestions were also made on the basis of these findings. 

   

• Effects of organic fertilizers from coconut coir and bagasse on the growth and yield of red amaranth and heartleaf in the greenhouse

  NGUYỄN THỊ NGỌC ÁNH, NGUYỄN THỊ MINH ANH (Author)

  Abstract | PDF (Vietnamese) | Views: 4 Downloads: 7

  This study was carried out to find the method for composting to produce organic fertilizer and evaluate the effects of organic fertilizer from coconut coir and bagasse on the growth and yield response of red amaranth and heartleaf. Coconut coir and bagasse are treated before mixing with EM (effective microorganism) to create organic fertilizer. The experiment was arranged in a completely randomized design with four treatments and three repetitions: Treatment 1: no fertilizer, Treatment 2: inorganic fertilizer as recommended (50N-24P2O5-6K20/ha), Treatment 3: soil and organic fertilizers (1:1) + inorganic fertilizer (10N-4P2O5-2K20 kg/ha); Treatment 4: soil and organic fertilizers (3:7) + inorganic fertilizer (10N-4P2O5-2K20 kg/ha). The results have successfully built a simple composting process from coconut coir and bagasse. Besides, the yield results of red amaranth and heartleaf in the treatment using organic  fertilizer (1:1 and 3:7) gave the highest results and were statistically different from the rest of the treatments and helped reduce the use of chemical fertilizers up to 50% and increase crop yield. 

   

• Overcoming the short-term voltage drop in 15-bus distribution network using D-STATCOM

  NGUYỄN THẾ HOÀNG, NGUYỄN VIỆT TRUNG, NGUYỄN VĂN MINH (Author)

  Abstract | PDF (Vietnamese) | Views: 4 Downloads: 11

  This paper presents mathematical model and system simulation using D-Statcom device to overcome the short-term voltage drop of the power system. Specifically, the parameters on the distribution network and the load are referred to at branch 371 of Kien Giang province. The branch has a total of 15 bus including the loads of companies and enterprises. The system is built and simulated in MATLAB/Simulink software. In case of three-phase short circuit for 1-1. 2s at bus 01. The simulation results show that the voltage at the buses is significantly improved when the system uses D-Statcom devices. Specifically, the voltage at the buses at the beginning, middle and end of the line have an amplitude of over 0.9 pa. 

   

• Orthogonal diagonalization of matrices with integer eigenvalues

  Nguyễn Thanh Toàn, Lưu Thị Kiều Hưởng, Trương Thị Thúy Vân, Trần Hoài Ngọc Nhân (Author)

  Abstract | PDF (Vietnamese) | Views: 3 Downloads: 6

  This paper continues the topic of matrix with integer eigenvalues. We present a process to find matrices in which integer coefficients are orthogonally diagonalizable and the received diagonal matrix also has integer coefficients. In other words, we give a process to find symmetric matrices (orthogonal diagonalization) with integer coefficients whose eigenvalues are also integers.

• A method of error compensation of ultrasonic sensors on walking aided device for the blinds

  TRẦN THANH TÂN, NGUYỄN CHÍ NGÔN (Author)

  Abstract | PDF (Vietnamese) | Views: 4 Downloads: 9

  This paper presents a method of error compensation of ultrasonic sensors on a wearable device that has funtions of detecting obstacles ahead, left and right by ultrasonic waves, and create alerts in Vietnamese for the blinds. The operation system of microcontroller is integrated with the sensor error compensation function identified from experimental data, using the Levenberg-Marquardt least square algorithm. Experiments on the blinds indicate that error compensation algorithm can opererate effeciently in real conditions, and the ability on development of a low-cost device is absolutly feasible.

• Sliding mode power control for doubly fed induction generator

  NGUYỄN VĂN HẢI, TRẦN THANH HÙNG (Author)

  Abstract | PDF (Vietnamese) | Views: 4 Downloads: 16

  An active and reactive power sliding mode control for a doubly fed induction generator (DFIG) is proposed in this paper. The DFIG is an asynchronous three-phase electrical machine with open rotor windings which can be fed by external voltages and widely used in high power fields. The sliding mode control is designed to ensure that the actual power of the DFIG follows the desired power in a finite time and reduces the chattering phenomenon around the sliding surface. The stability of the system is proven by Lyapunov's theory. Simulation results in MATLAB/Simulink show the effectiveness of the proposed controller without the overshoot is 0(%), the rising time of the active and reactive power achieves 0.0085(s) and 0.0051(s) respectively, the settling time is 0.0108(s) and 0.0126(s), and the setting error converges to 0. 

   

• Research on reducing total harmonic distortion for a five-level capacitor clamped single-phase inverter by carrier modulation technique

  HUỲNH THỊ TRÚC, NGUYỄN VĂN NHỜ (Author)

  Abstract | PDF (Vietnamese) | Views: 2 Downloads: 12

  This paper presents the survey results on the total harmonic distortion on a five-level capacitor clamped single-phase inverter (FLC-5L) with a load using R-L. The article studies the PWM control methods and compares unwanted harmonic distortion in the FLC-5L capacitor clamped single-phase voltage inverter. Carrier modulation (PWM) technique is used in this study because it is simple and easy to implement. Control techniques are simulated and compared on Matlab/Simulink software version 2021. The research results show that at modulation index m = 1 and carrier frequency fc = 5kHz, the proposed PS control technique achieves THD_I = 1.68% lower than that of PD, POD and APOD.

• Influence of road quality and suspension stiffness on passenger vehicle oscillation in Vietnam

  PHẠM THÀNH LUÂN, LƯƠNG VĂN VẠN (Author)

  Abstract | PDF (Vietnamese) | Views: 4 Downloads: 5

  In Vietnam, passenger vehicles are used a lot in the transportation of passengers, suitable for circulation on small roads or rural roads. Meanwhile, these roads in our country have not been completed, and in many places, the road surface is not flat with high roughness. Therefore, when the vehicle is running on the road, it will vibrate, reduce the motion smoothness, generate dynamic loads, damaging some parts the road surface. The article presents the results of research on the influence of road surface quality on the vibration of passenger vehicles by building a dynamic model of the vehicle. The research results are to suggest the optimal stiffness of the passenger vehicles suspension system to minimize the vibration from the rough road surface to the vehicle's body, bringing comfort to the driver and passengers.