F. Farina

Improved current control strategy for power conditioners using sinusoidal signal integrators in synchronous reference frame

In this paper, an improved current control scheme for shunt type power conditioners is proposed, with the aim of simplifying current harmonic compensation for industrial implementations where strict limitations on the harmonic distortion of the mains currents are required. To compensate current harmonics, the proposed scheme is based on proportional-integral regulators using sinusoidal signal integrators, implemented to operate both on positive and negative sequence signals. One regulator, for the fundamental current component, is implemented in the stationary reference frame. The other regulators, for the current harmonics, are implemented in a synchronous reference frame rotating at the fundamental frequency. This allows to compensate simultaneously two current harmonics with just one regulator. The whole control algorithm has been implemented on a 16-bit, Fixed-point digital signal processor (DSP) platform controlling a 20 kVA prototype. Experimental results are presented to show the validity of the proposed solutions.

Direct torque control for dual-three phase induction motor drives

A direct torque control (DTC) strategy for dual-three phase induction motor drives is discussed in this paper. The induction machine has two sets of stator three-phase windings spatially shifted by 30 electrical degrees. The DTC strategy is based on a predictive algorithm and it is implemented in a synchronous reference frame aligned with the machine stator flux vector. The advantages of the discussed control strategy are: constant inverter switching frequency, good transient and steady-state performance and low distortion of machine phase currents respect to direct self control (DSC) and other DTC schemes with variable switching frequency. Experimental results are presented for a 10 kW DTC dual three-phase induction motor drive prototype.

Analysis of the asymmetrical operation of dual three-phase induction machines

The paper deals with the problem of the unbalanced current and power sharing in the dual three-phase induction machine supplied by a sinusoidal voltage source. In particular, the case discussed has two three-phase sets of full-pitch windings, spatially shifted by 30 electrical degrees with isolated neutrals. The unbalanced current sharing between the two winding sets is due to the not eliminable small system asymmetries. First, the machine model to compute the unbalances is presented; second, the analysis of the system asymmetries and their effects on the machine operation is discussed. Simulated and experimentally tested sinusoidal supply conditions are presented for a 10 kW dual-three phase induction machine prototype.

Dual-Source Fed Multi-phase Induction Motor Drive for Fuel Cell Vehicles: Topology and Control

The paper introduces a new multi-source fed drive topology based on a multi-phase induction machine. The reference application is the hybrid fuel cell (FC) traction system (fuel cell and battery). The FC power and the battery power are directly added at the machine level, without any additional DC-DC converters. The proposed drive topology uses two three-phase inverters having different DC link voltages provided by the FC and the battery, respectively. The two inverters, controlled by an unique control system, supply a dual three-phase induction motor having two sets of stator three-phase windings spatially shifted by 30 electrical degrees. In this drive topology, the machine can operate asymmetrically and the control system must be able to cope with different power levels in the two sections of the drive. A rotor field oriented control strategy has been implemented using a stationary frame current control scheme. Experimental results are presented for a 10 kW dual three-phase induction motor drive

Stationary frame digital current regulation for dual-three phase induction motor drives

A digital current regulation scheme in stationary reference frame for dual-three phase induction motor drives is discussed in the paper. The induction machine has two sets of three-phase stator windings spatially shifted by 30 electrical degrees. The stator windings are fed by a current controlled PWM (CRPWM) six-phase IGBT voltage source inverter (VSI). The basic issues are the current regulation scheme to cope with the inherent asymmetries of the drive and the digital implementation to have zero steady-state current error for the whole frequency range of the drive. Experimental tests are presented for a direct rotor field oriented control (DRFOC) of a 10 kW dual three-phase induction motor drive prototype; the results confirm the validity of the control scheme.