Analysis of extended Constant Power Speed Range of the Permanent Magnet Synchronous Machine driven by Dual Mode Inverter Control

The scope of this work is the Permanent Magnet Synchronous Machine (PMSM) operating at Constant Power Speed Range (CPSR). The proposed technique to drive the PMSM at CPSR is the Dual Mode Inverter Control (DMIC) The mam idea behind DMIC is to change the three-phase operation of the PMSM below base speed to hybrid, single-phase and three-phase, operation above the base speed This technique allows driving the PMSM in a wide CPSR The DMIC uses three facts to achieve wide CPSR First, it introduces the idea of the advance angle, which allows driving current into the machine while the back-emf is smaller than the DC link voltage Second, the blanking angle is used to maximize the electrical to mechanical power conversion by increasing the on time of the transistors of the Voltage-Fed Inverter (VFI) and therefore slowing down the decreasing voltage m the outgoing phase Finally, this technique avoids regeneration through the bypass diodes by introducing an ac-voltage controller interfacing the VFI and the PMSM. The analysis of DMIC/PMSM drive system shows that it uses the same principle of Vector Control with Field Weakening (VCFW) i e., the armature current is controlled to have a field component that weakens the air gap field, and therefore opposes the back emf However, the armature current vector must satisfy the voltage and current constraints, which are the maximum current and armature voltage. In VCFW, the voltage limit circle shrinks fast as speed increases because the maximum armature voltage is the maximum output voltage of the VFI, which is limited by the DC link voltage In DMIC, on the other hand, the voltage limit circle shrinks slower, since after the commutation period the machine is operating in single-phase mode The total armature voltage is the contribution of the DC link voltage, the back emf, and the induced voltage provided by the derivative of the on-phase currents In fact, this operation eliminates the voltage constraint, and the machine can operate at any speed, and then the only constraint is the current limit Therefore, it is shown in this work that theoretically there is no speed limit for DMIC driving PMSM over constant power operation rang

Type-III resolver-to-digital converter using synchronous demodulation / Tipo-III conversor resolver-para-digital utilizando a desmodulação síncrona

Resolver is an angular position sensor widely used in applications such as electric/hybrid vehicles, CNCs, antennas and robotics. However, the estimation of the angular position from resolver outputs is more difficult than the analysis of encoder signals, and it is still an open question. Most algorithms proposed in literature are based on type-I or type-II angle tracking ob- servers. Some type-III observers were proposed, but they require a high sampling frequency. This paper explores the use of synchronous demodulation of the resolver outputs to simplify the implementation of a type-III angle tracking observer. The resolver outputs are sampled at the peaks and valleys of the excitation resolver signal, being easy to get sine and cosine of the angular position. The proposed approach reduces the computational cost and the required sampling frequency to implement the type-III observer. Simulation and experimental results prove the accuracy of the proposed approach.

Energía, espacio, territorio y desarrollo local: el uso del gas natural en las cerámicas de Mato Grosso del Sur

El presente artículo busca enfocar la correlación entre el uso de la energía, el espacio, el territorio y el desarrollo local, teniendo en cuenta la utilización del gas natural en las cerámicas de Mato Grosso del Sur/Brasil. La importancia de los hechos geográficos es pautada por muchos parámetros, como el paso del tiempo, los nuevos descubrimientos tecnológicos, las necesidades de materias primas, los objetivos nacionales e internacionales y la ética de las relaciones internacionales. El gas natural no es utilizado aún como fuente alternativa de energía en gran escala en el Estado. Puede ser considerado como uno de los resultados de la valorización de la política socio económica, de la cultura local y del medio ambiente preservado como parte de la identidad local del ser humano al mejorar su calidad de vida.The article in handseeks to focus on the correlation between the use of energy, space, territory and local development, bearing in mind the utilization of natural gas in the production of ceramics in Mato Grosso do Sul, Brazil. Natural gas is still not utilized as an alternative source of energy on a large scale in the State. It can be considered as one of the results of the valorization of socio-economic policy, the preservation of local culture and the environment as part of the local identity of the human being in improving their quality of life

Implementation and Performance Evaluation of a Community-Scale Adobe Evaporative Cooling Chamber for Vegetable Preservation

The construction of evaporative coolers in remote areas can increase the longevity of vegetables, improving food security and the local economy of small farmers in remote, impoverished communities without access to electricity. This work presents a 1:1 scale prototype of an 8 m3 (2.1 × 2.1 × 2.3 m) stabilized adobe evaporative cooler, with a design based on the appropriate technology framework, and it was built as a chamber using double adobe walls, filled with wet sand, to induce evaporative cooling. Furthermore, the paper presents the prototype’s performance evaluation. The tests were carried out in the dry and wet states, with different volumes of water. The results show good performance compared with other prototypes, although the optimum watering volume could not be determined because of the high climate variance (outside temperature and humidity) that prevented the repetition of the experiments in identical operating conditions. Stabilized adobe proved to be a good choice for use in the cooler, even when subject to moisture accumulation, indicating an estimated long lifetime for the cooler. The data obtained about the efficiency of evaporative cooling show that the cooler, as expected, has its best performance on the hottest and driest days, reducing the internal temperature (up to 13.24 °C) and managing to keep the internal humidity. The cost, efficiency, durability, and replicability make the proposed evaporative cooler a feasible solution for food preservation

Metodologia para rastreamento com modificação dos zeros e rejeição de distúrbio aplicada a sistemas incertos

Propõe-se uma metodologia para rastreamento de sinais e rejeição a distúrbio aplicada a sistemas incertos, com incerteza do tipo politópica. Realiza-se o processo de atenuação do efeito do sinal de distúrbio na saída do sistema através da realimentação dinâmica da saída utilizando-se um controlador Kp(s) que minimiza a norma H2 de custo garantido de w(t) para z(t), sendo w(t) o sinal de distúrbio e z(t) a saída do sistema. Então, para o rastreamento de sinais utiliza-se a modificação ótima dos zeros a fim de minimizar a norma H¥ de custo garantido da função de transferência entre o sinal de referência e o sinal de erro de rastreamento, sendo o erro de rastreamento a diferença entre o sinal de referência r(t) e o sinal de saída z(t). O projeto de rastreamento de sinais e rejeição do efeito do ruído presente na planta é descrito na forma de LMIs que, quando factíveis, pode-se obter a solução ótima para o problema. Exemplos ilustram a viabilidade da metodologia proposta.The methodology for tracking system and disturbance rejection considering polytopic uncertainties in the plant is proposed in this work. The process of disturbance rejection is make though of the dynamic feedback of the system using a controller Kp(s) that minimize the H2-norm guaranteed cost from w(t) para z(t), where w(t) is the disturbance signal and z(t) is the output of the system. and so, one use the optimal zeros modification with purpose of to design the tracking system. In this way, the modification of the zeros is used to minimize the H¥-norm guaranteed cost from the reference input signal to the tracking error signal, where the tracking error signal was diference between the reference input signal and output signal of the system. The design is formulated in Linear Matrix Inequality (LMI) framework, when it presents a solution, the optimal solution of the stated control problem is obtained. Two practical examples illustrate the effectiveness of the proposed method.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Controle ótimo H∞ de sistemas não-lineares com modelos fuzzy takagi-sugeno

Neste trabalho é proposta uma metodologia de rastreamento de sinais e rejeição de distúrbios aplicada a sistemas não-lineares. Para o projeto do sistema de rastreamento, projeta-se os controladores fuzzy M(a) e N(a) que minimizam o limitante superior da norma H∞ entre o sinal de referência r(t) e o sinal de erro de rastreamento e(t), sendo e(t) a diferença entre a entrada de referência e a saída do sistema z(t). No método de rejeição de distúrbio utiliza-se a realimentação dinâmica da saída através de um controlador fuzzy Kc(a) que minimiza o limitante superior da norma H∞ entre o sinal de entrada exógena w(t) e o sinal de saída z(t). O procedimento de projeto proposto considera as não-linearidades da planta através dos modelos fuzzy Takagi-Sugeno. Os métodos são equacionados utilizando-se inequações matriciais lineares (LMIs), que quando factíveis, podem ser facilmente solucionados por algoritmos de convergência polinomial. Por fim, um exemplo ilustra a viabilidade da metodologia proposta.A design method for tracking system with disturbance rejection applied to nonlinear systems using fuzzy control is proposed in this paper. Fuzzy feedforward controllers M(a) and N(a) are designed in order to obtain the tracking system. These controllers minimize the H∞-norm from the reference input signal r(t) to the tracking error signal e(t), where the tracking error signal is the difference between the reference input signal r(t) and the output signal z(t). A dynamic feedback fuzzy controller Kc(a) is designed in order to minimize the H∞-norm from the disturbance input w(t) to the output z(t). The designs are formulated in Linear Matrix Inequality (LMI) framework, such that the optimal solutions of the stated control problems are obtained. Simulation of a practical problem illustrates the effectiveness of the proposed method

A school-based intervention for a better future: study protocol of Sintra Grows Healthy

Background: Preventing childhood obesity is a public health challenge of the twenty-first century and it must be a priority. Governments play a major role in creating and supporting a healthy school environment and should prioritize actions to improve children's health. Sintra Grows Healthy aims to promote healthy lifestyles to prevent childhood obesity and improve children's health-related quality of life and social and emotional skills, through the development of a school evidence-based and sustainable model. Methods: This protocol describes a quasi-experimental design and community-based participatory research. The participants included in the study are the school community of Portuguese public primary schools from the municipality of Sintra. Data will be collected on demographic and socio-economic characterization, nutritional status, eating habits and behaviors, physical activity, sedentary behaviors and sleep, health-related quality of life, and social and emotional skills. Discussion: There is evidence to support interventions in school settings as strategies for obesity prevention. Up-to-date homogeneous and community-based interventions for preventing childhood obesity are lacking, therefore Sintra Grows Healthy intends to fill this gap. Furthermore, Sintra Grows Healthy aims to contribute with relevant scientific findings that will allow the development of better strategies for policymakers and society to manage this major public health problem.info:eu-repo/semantics/publishedVersio