A self-bearing motor (SBM) is an electric motor with a magnetically integrated bearing function, that is, it can provide levitation and rotation simultaneously as a single actuator. This paper presents the design, operating principle and control system for the slotless self-bearing motor (SSBM). In this design, the stator has no iron core but includes six-phase coils. The rotor consists of a permanent magnet and an enclosed iron yoke. Magnetic forces generated by the interaction between stator currents and the magnetic field of the permanent magnet are used to control the rotational speed and radial position of the rotor. In this paper, the torque and radial bearing forces are analyzed theoretically with the aim to develop an improved control system. In order to confirm the proposed control method, an experimental system was constructed and tested. Simulation and measurement results show that the SSBM can work stably in modes such as start, reverse, rotation load and external radial pulse forces.

The authors acknowledge and thank the Ministry of Science and Technology of the Republic of China for their partial financial support of this study under Contract Number MOST 109-2622-E-992-008 -CC3.

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The disturbance and uncertainty of the motor drive systems are very complicated terms. There is no exception for the slotless-self bearing motor (SSBM), where the perturbations of the bearing motor are mainly came from the outside as the wind affect, from inside as the thermal changing of the coils, and incorrect modeling of the winding processes. First, to delete these inversed terms, this paper proposes a new super-twisting disturbance observer (STDOB) to obtain the desired goal of the robust control design. The proposed disturbance observer was based on the information of measured and estimated states with the aim of softening the cost of the measurement. Second, to estimate the velocities and accelerations of the movements on x  and y  axes, the stability concept of homogeneous function-based was used to design the fixed-time state observers (FTSOBs) for these axes. The state of the rotational operation on   axis was estimated with a fixed-time state observer. Third, to control the positions and rotational speed, a variable boundary layer thickness (VBLT) fixed-time sliding mode control (FTSMC) was designed to force these positions and speed states converge to the desired goals. Finally, the stability of the proposed control algorithm was theoretically verified by using Lyapunov condition and simulation of MATLAB software. The obtained states were acceptably stable with small overshoots, small settling-times, and stable steadystates.INDEX TERMS Slotless-self bearing motor, super-twisting disturbance observer, variable boundary layer thickness, fixed-time sliding mode control.

Nowadays, small- and medium-sized enterprises play crucial roles in both developed and developing countries. They create new employment, fulfill the market gap, contribute to Gross Domestic Product and boost the whole economy. However, small- and medium-sized enterprises face more financial constraints than large enterprises, which prevent them from growing and expanding their activities. This paper aims to investigate how the innovation of small- and medium-sized enterprises impacts on credit accessibility in Vietnam from 2005 to 2015, through five aspects of innovation: new products, new technology, improved existing products, research and development investment, and machine innovation. The data set consists of more than 4500 observations of small- and medium-sized enterprises in Vietnam. This data set is taken from a survey conducted within the framework of cooperation among UNU-WIDER, the University of Copenhagen and Vietnamese government agencies. Using panel regression model, we found out that three out of five innovation factors significantly impact on credit accessibility. More specifically, research and development investment and new product have negative impact on credit accessibility; whereas new technology has positive impact on credit accessibility. These findings are useful for firm managers, banks and policy makers to help small- and medium-sized enterprises overcome financial constraints through innovation aspects.

A significant solution to achieve energy efficiencies and stability of the electrical network is upgrading auto-consumption in a single PV system. In this paper, we presented a methodology to implement low-cost sensors and actuators to have better monitoring and control for a feasibility solution. This approach has been conducted through a case study on Greenhouse’s PV system in Grenoble, France. We proposed a minimal set of sensors to reduce system complexity while giving us enough information to make decisions. Some technical issues were analyzed as accuracy, sampling rate, response-ability of our system. The influences of inverter operation mode to system losses were considered. After that, we figured out energy problematics in our system based on available design data and simulation data from PVSyst. A PV production prediction model was investigated with input as forecast cloudiness data collected from web service, updated every 3 hours. This model, combined with real-time monitoring data and setting mode on an off-grid inverter, was used to identify control strategies with objectives of avoiding oversize storage capacity and maximizing the autonomous duration of the PV system.

This paper proposes a new disturbance observer concept based on the information of the estimated and measured signals for a micro-electro-mechanical system. First, the sliding-mode observer based on the linear matrix inequality was designed to estimate the states of a micro-electro-mechanical system gyroscope. Second, a new disturbance observer was proposed for estimating perturbations of the T-S fuzzy micro-electro-mechanical system gyroscope. Third, the double phase’s fixed-time sliding-mode control was designed to control the positions and velocities of the MEMS system. The proposed disturbance observer input signals were taken into account from the measured and estimated signals. Two cases of high magnitudes and high frequencies disturbances were used to test the power of the proposed disturbance observer. Fourth, the Lyapunov condition was used to verify the corrections of the proposed controller and observer. Finally, the simulation by using MATLAB software was used to show the power of the proposed methods. The achievements of the small reaching-time, small tracking error, and stable steady-states under the vibration form outside of the system.