Control of a three-phase wound-rotor induction motor drive for automation applications

The use of rotary assembly platforms, such as the automated box-fill system rotary table, is widespread in automation applications. One of the problems that the designers have to face is how to transfer the power to the auxiliary actuators mounted on the rotating platform. In this paper, this problem is solved by adopting a direct drive three-phase wound-rotor induction machine that can independently control the rotor torque and the power flow delivered to the rotor loads. To achieve this result, a high-frequency component is added to the air-gap magnetic field to generate an adjustable electromotive force in the rotor windings. Some experimental results are shown to confirm the feasibility of the control scheme

Overmodulation Strategies for an Open-End Winding Induction Motor Drive with a Floating Capacitor Bridge

This paper considers a 3-phase induction motor with open-end windings fed by a primary bridge connected to the main power source and a floating bridge. The floating bridge supplies the motor with the required reactive power, while the primary inverter only exchanges active power with the main power source. This greatly extends the speed range over which the drive can operate at rated power. To further utilize the input power source, the primary inverter can work in the overmodulation region, and the floating bridge, acting as a harmonic compensator, improves the quality of the current flowing through the motor phases. Also, the paper includes some considerations on the sizing of the floating capacitor. Three different overmodulation techniques are evaluated and compared in terms of peak torque/power and efficiency. The highest performance is obtained when the main inverter generates a six-step voltage waveform, which increases motor power by almost 20% and ensures a broader speed range at maximum efficiency

Control System for Open-End Winding Surface PM Synchronous Machines with a Floating Capacitor Bridge

A speed control scheme is presented for a 3-phase permanent magnet synchronous machine with an open-end stator winding fed by a dual inverter system with a floating bridge. The floating bridge inverter is used to compensate the reactive power of the main inverter and, hence, to maximize the active power delivered to the motor in compliance with the constraints of a limited current and voltage. The DC-link voltage of the floating bridge varies depending on the operating condition of the motor in order to reduce the switching losses and ensure the controllability of the system. The experimental results show that a significant improvement in the width of the speed range at constant power is achievable in the flux weakening region. © 2018 IEEE

Comparison of Three Voltage Saturation Algorithms in Shunt Active Power Filters with Selective Harmonic Control

An array of proportional-resonant regulators is often used in shunt active power filters to control the grid currents and reduce the harmonic distortion caused by a distorting load. The voltage that is necessary to compensate for the current harmonics must be consistent with the available dc-link voltage. In this article, three adaptive algorithms for the exploitation of the dc-link voltage are developed and compared. These algorithms adaptively change the voltage saturation of each regulator to preserve the control capability of the fundamental component of the current when the available voltage is not enough to control the filter current. Simultaneously, they try to improve the quality of the grid current because the dc-link voltage of the active power filter is allocated to the regulators to compensate only the most significant harmonics. Some experimental results are shown to demonstrate the feasibility of the three algorithms

Robust control of an open-ended induction motor drive with a floating capacitor bridge over a wide speed range

An electric drive for high-speed applications is analyzed in this paper. The drive consists of a dual two-level inverter with a floating bridge, fed by a single voltage source, and a 3-phase induction motor with open-ended stator windings. The floating bridge compensates the reactive power of the motor, so that the main inverter operates at unity power factor and fully exploits its current capability. The constant power speed range of the motor can be significantly extended depending on the DC-link voltage of the floating inverter. The details of the control system are examined and the feasibility of an electric drive is experimentally assessed

B. Snell, Noi e gli antichi Greci. Nove giorni di latino

Edizione italiana, con introduzioni, traduzione, note di commento e indici di due saggi di B. Snell, uno dei massimi filologi classici del Novecento. Progettata da Marilena Amerise e Hartmut Erbse, entrambi scomparsi, l'impresa è stata portata a compimento da G. Alvoni, V. Garulli e C. Neri. G. Ravasi ha scritto una toccante introduzione sulla figura scientifica e umana di Marilena Amerise, prematuramente morta a 33 anni il 27 febbraio 2009