G. Maragliano

A Novel approach for DC-link voltage ripple reduction in cascaded multilevel converters

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 system. Several results are presented, which confirm the validity of the proposed approach

FPGA implementation of a sensorless PMSM drive control algorithm based on algebraic method

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, using an algebraic approach and aimed to low speed range applications. High frequency injection allows, by means of simple mathematical relationships, the estimation of motor characteristic inductances. The machine inductances are characterized by a certain degree of position dependent magnetic saliency, as a function of the shaft position, in particular the mutual inductance value, which is proportional to the error between the true angle and an estimated angle value. The angle error is utilized as error signal, in a phase locked loop technique, in order to track the motor position and speed. The proposed solution has been implemented in a low cost FPGA platform.

A new generalized fault tolerant space vector modulator for cascaded multilevel converters

A new generalized fault tolerant space vector modulator for cascaded multilevel converters is presented. Exploiting the redundancy properties inherent in multilevel modulation schemes, a generalized space vector modulation algorithm is devised, also aimed to the extension of the normal, full rated operation, to a limited rate, fault tolerant mode. Based on the exploitation of switching vectors redundancy properties and discontinuous modulation technique, solutions have been devised for the equalization of semiconductor components switching frequency, in either no-fault and fault operating conditions, in order to reach an equal distribution of converter dissipated power. The new fault tolerant space vector modulation technique is validated through a case study.

Optimal operation mode for Modular Multilevel Converter based HVDC

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 general working point are object of investigation. The main four working points, inverter, rectifier, inductive and capacitive, are studied in detail.

A sensorless PMSM drive with inductance estimation based on FPGA

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 inductances values are utilized, in real time mode, as parameters, in the field oriented control of the permanent magnet synchronous motor for an improved robustness. A sensorless drive, based on the algorithm presented, has been tested on a low cost field programmable gate array (FPGA) platform. A simple communication protocol, between host PC and FPGA board, has been designed and implemented, for algorithm parameters real time update and state observation.

Effects of the 2 nd order harmonic leg current in a MMC converter

In this paper an exhaustive analysis of the utilization of the second harmonic component of the circulating currents in a modular multilevel converter for HVDC application is presented, with the aim of highlighting the effects on the maximum arm energy ripple, i.e. capacitors voltage ripple, and on semiconductor losses. Simulation results are presented and design remarks are indicated.

A new N-level space vector modulator for cascaded multilevel converters

A new generalized space vector modulator for cascaded multilevel converters is presented, featuring centralized control, fault tolerant and common mode voltage reduction capabilities. The SVPWM technique is based on the redundancy properties inherent in multilevel modulation schemes and is validated through a case study. Simulation and experimental results are presented.

A novel Direct Torque Control strategy for high power induction motor drives

A new induction motor control scheme is presented, by which, starting from the stator flux orientation concept and from the theory of Direct Torque Control, the modulation is made always synchronous. In particular, it becomes possible to reduce the torque harmonic components in the range 0–100 Hz, which can be an important achievement in high power applications.