This article presents the mathematical formulations of two Overmodulation Strategies (OSs) for two-level inverters. The OSs aim to minimize the Equivalent Total Harmonic Distortion (THDe) or the Equivalent Weighted THD (WTHDe) of the αβ reference modulation indexes accomplishing the desired fundamental frequency magnitude. Straightforward analytical forms using just the first π/6 radians were built to approximate the solutions given by numerical optimization. The proposed OSs were compared to the state-of-the-art OSs, verifying their optimal performance in the whole overmodulation range. Experiments with an RL load allow observing the inverter commutation’s effect when implementing the proposed OSs for different switching frequencies.

This paper proposed a modulation strategy for a hybrid converter, composed by a n-cell Flying Capacitor Converter (FCC) and a classical two-level inverter. The balancing of the inner capacitors is done with logical circuits, while current control is performed with the Optimal Switching Sequence MPC. The simulation results show a good dynamic performance and an improvement of the harmonic spectrum is presented, compared to the classic two-level inverter.

In the last past years, some countries are enforcing stringent grid codes to regulate the connection of Wind Energy Conversion Systems (WECSs) to the electrical network, mainly because of the high penetration of electric power from this renewable source. Additionally, the trend of wind turbines has shown an ongoing power rating growth, reaching sizes up to 10 MW. Multilevel converters have appeared as a solution for large WECSs, due to its high reliability, controllability and the capability to reach high power ratings. This paper presents a control strategy for the application of the Modular Multilevel Matrix Converter in Multimegawatts Wind Turbines. Extensive computer simulations and a downscaled laboratory prototype, with twenty-seven power cells, are presented to validate the effectiveness of the proposed control system.

Drives based on modular multilevel topologies are the next generation of high-power/voltage converters. In this paper, the Modular Multilevel Converter model is extended to the Back to Back scheme, allowing its control as an unique system, instead two separated converters. Additionally, the proposed control strategy is able to regulate the ac ports and to perform the voltage balancing in both converters by using circulating currents and common mode voltage, providing independence between the converters and the ac ports. Extensive computer simulation and a laboratory prototype of a Modular Multilevel Converter with eighteen power cells feeding an induction machine validate the effectiveness of the presented control algorithm.

In this paper a new methodology to compensate double-frequency power oscillations in unbalanced 4-leg distribution networks is presented. The zero sequence components in the voltages and currents are used to provide an extra degree of freedom to compensate reactive and active power pulsations. A novel closed-loop algorithm for the compensation of fluctuations in the converter side, instead of the grid side is presented in this work. Simulation results are discussed, validating the proposed control system.

The teleoperation of mobile social robots requires operators to understand facial gestures and other nonverbal communication from a person interacting with the robot. It is also critical for the operator to comprehend the surrounding environment in order to facilitate both navigation and human-robot interaction. Allowing the operator to control the robot's gaze direction can help the operator observe a person's nonverbal communication; however, manually actuating a gaze increases the operator's workload and conflicts with the use of the robot's camera for navigation. To address these problems, the authors developed a teleoperation system that combines automatic control of the robot's gaze and a 3-D graphical representation of the surrounding environment, such as location of items and configuration of a shop. A study where a robot plays the role of a shopkeeper was conducted to validate the effectiveness of the proposed gaze-control technique and control interface. It was demonstrated that the combination of automatic gaze control and representations of spatial relationships improved the quality of the robot's interaction with the customer.

A critical problem in planning sampling paths for autonomous underwater vehicles is balancing obtaining an accurate scalar field estimation against efficiently utilizing the stored energy capacity of the sampling vehicle. Adaptive sampling approaches can only provide solutions when real-time and a priori environmental data is available. Through utilizing a cost-evaluation function to experimentally evaluate various sampling path strategies for a wide range of scalar fields and sampling densities, it is found that a systematic spiral sampling path strategy is optimal for high-variance scalar fields for all sampling densities and low-variance scalar fields when sampling is sparse. The random spiral sampling path strategy is found to be optimal for low-variance scalar fields when sampling is dense.