Search

This paper proposes a control and monitor of single-stage single-phase T-type grid-connected inverter based on IoT. The MPPT (maximum power point tracking) algorithm, modulation method of single-phase T-type, the PR (proportional-resonant) current controller, and SOGI PLL algorithm are presented in this paper. With H-bridge, the level of inverter voltage is 3, the low level is the cause of the appearance of harmonic components and power loss in the grid- connected solar application. To overcome this problem, this paper adopts a T-type single-phase with 5 voltage levels. The presented inverter has a half-bridge switching leg and a T-type switching leg. Besides, the grid-connected energy can be easily supervised during DSP processing via the ESP32 wi-fi module by the UART interface. A prototype and mobile app are built for performance verification, which can test single-phase T-type topology. Simulation and experimental results are presented to verify the effectiveness of the proposed strategy.

This paper concerned with the development and implementation of smart street lighting control system based using Led lamp and Lora Wireless communication. Currently, a traditional street lights are automatically turn on or off based on timer or day/night sensor. Recently, the conventional light sources are replaced by Led, which have so many advantages such as: energy savings, long lifetime, high reliability, pure light color, fast response, and friendliness to the environment. Furthermore, the intensity of the LED can be controlled easily. In this paper, the smart lighting system is designed to control and monitor devices via wireless transmission frequencies below 1 GHz. The smart lighting system has been built at Hochiminh City University of Technology to meet the standards for data transmission.

Predictive current control is the use of predictive model for controlling load current tracking reference value, which forecasts future current values based on the selection one of the 27 voltage vectors of T-type NPC inverter. The cost function will minimize tolerance between control and reference current and 2 capacitor voltage values. These distortions depend on system load parameter elements. However, they are not the constant in the real event, which vary with operational conditions causing the distortion in control. In this paper, the new inductance estimation method is applied to predict future inductance values on-line, future current values as well as voltage values of 2 capacitors in order to improve the current quality. The proposed method is introduced and compared with the conventional algorithm to express the advantage of new technique. Simulation results are obtained by PSIM software and experimental results verify the feasibility and effectiveness of the algorithm.

This paper proposes the modified SVPWM control algorithm for the three-phase voltage source inverter, which consists of traditional six switches voltage source inverter and three bidirectional switches for creating the ac decoupling circuit. This topology has the advantages such as the ability to reduce the overall power losses in inverter system and beside that, to decrease the leakage ground current from PV panel (in case of photovoltaic systems) which is based on the principle of decoupling when the zero space vectors occur. For avoiding shoot-through states between six traditional switches and three bidirectional switches, a delay time has been inserted into switching time. The delay time has been controlled more complex to guarantee THD of output voltage, it's called three-step switching algorithm. In oder to demonstrate the feasibility of this algorithm, the operation of the inverter and the modified SVPWM method is simulated by using Matlab/Simulink software and implemented in the experimental prototype by using FPGA Virtex 5 (Xilinx).

Single-state PWM technique (SS PWM) presents an optimised switching losses PWM scheme to be applied for multilevel inverter for possible reducing number of switchings in a sampling period. Nonlinear control characteristics and harmonic distortion factor can be significantly improved if the number of levels is high. To implement a single-state PWM control with minimised voltage error on condition of unbalance dc sources, a compensating technique is required. The paper will propose a possible solution for implementing the SS PWM with minimised voltage error, using carrier based approach. This again demonstrates the utilisation of carrier based and space vector PWM relationship in solving various optimised PWM problems in multilevel inverters.

Nowadays, an intensive development of multilevel inverters has been seen in hybrid and fuel cell electric vehicles. For this, a high voltage cascade inverter with step pulse PWM strategy is an applicable topology as it can reduce electromagnetic interference as well as switching losses on power devices. The converter is usually controlled with a look-up table of commutation angles, which are computed off-line base on an assumption of equal dc voltage sources. However, in reality, the inequality of these dc voltage sources can occur due to different charging/discharging processes and this reduces the quality of output voltages such as the existence of low order harmonics and an error in fundamental voltage. To overcome this problem, PWM angles in the look-up table can be changed according to different cases of dc source variation. However, this solution may require a large memory for the look-up table. Thus, off-line PWM stratergy in case of dc voltage source variation may not be a suitable approach to control the converter. In this paper, an on-line step pulse PWM method will be proposed to control fundamental voltage and reduce the amplitudes of low-order harmonics to possibly low values. Similar to the original on-line method, the control principle between two defined trajectories will be appropriately modified for solving the problem. The principle is mathematically formulated, and demonstrated by simulation results.