L. Vaccaro

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A new cascaded multilevel converter structure is proposed, which allows a remarkable reduction of the DC-link voltage ripples, owing to the implementation of a new devised control strategy. The new topology uses only an additional controllable switch-diode couple for each basic H-bridge cell, with a small increment in cost and complexity of the converter(More)
A new PWM technique, capable of achieving a correct dc-link capacitor voltages balance in Diode- Clamped Multilevel inverters, within the limits defined by the theory, is presented. This result is obtained while decreasing the switching power losses when compared to techniques based on the use of redundant switching vectors. The combined use of such a(More)
In this paper an analytical study on the Modular Multilevel Converter architecture applied to HVDC is presented. The influence of the circulating injected currents on the converter performance is the main object of this analysis. In particular, the influence of the second and fourth harmonics circulating injected current on the capacitor voltage ripple in a(More)
A new PWM technique, capable of achieving a correct dc-link capacitor voltages balance in Diode-Clamped Multilevel inverters with Active Front End (AFE), beyond the limits defined by the theory for converters without AFE, is presented. A detailed explanation of the new devised PWM technique and the main results are reported with analytical computations.
In this paper, a new algorithm for position and speed estimation in permanent magnet synchronous motors is presented, which is based on the high frequency permanent motor model and on high frequency signal injection, uses an algebraic approach and is aimed to low speed range applications. High frequency injection allows, by means of simple mathematical(More)
An analysis of the efficiency of AC/DC/AC diode-clamped multilevel converters is presented, where commanded and suitable variations of the DC-link voltages are proposed in order to decrease the energy losses. The study is carried out also aiming at the correct DC-link capacitor voltage balance, obtained with additional chopper stages together with a new PWM(More)
A new algorithm for position and speed estimation in permanent magnet synchronous motors is presented, which is based on the high frequency signal injection and uses an algebraic approach. Motor inductances are estimated by simple mathematical relationships and motor position and speed are tracked using a phase locked loop technique. The estimated machine(More)
The reduction of the stator flux in an electrical machine moving at constant speed causes the reduction of the voltage at the machine terminals. In the field of electrical drives this phenomenon leads to the common convincement that the reduction of the reference stator flux, while leaving the speed unchanged, always avoids the saturation of the voltage(More)
In high power ac motor drives, power semiconductor devices are allowed to switch at a quite low frequency, which is generally limited to a few hundreds hertz. Therefore, high torque harmonic components in the 0-1000 Hz frequency range often arise, which may compromise the processes accuracy and the products quality. The asynchronous pulse width modulation(More)
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