Maria Carmela Di Piazza

Evaluation of Common Mode Disturbance Mitigation Devices in AC Motor Drives through HF Modelling

In this paper a method for verifying the performance of both passive filters and active compensation devices for common mode disturbance mitigation in PWM induction motor drive is presented. The method is based on the use of a lumped parameters HF circuit model of the whole drive simple to be implemented and studied through a standard circuit simulation software such as PSpice. Two solutions to reduce the common mode current flowing through the earth connection of the motor have been set up, these solutions are based respectively on a passive common mode choke and on an active common mode canceller. The comparison between simulated data and experimental tests allows to assess the suitability of the proposed model to accurately predict the impact of the different mitigation devices on common mode HF currents propagating within the drive

Induction-Machines-Based Wind Generators With Neural Maximum Power Point Tracking and Minimum Losses Techniques

This paper presents an induction machine (IM)-based wind generation unit with integrated maximum power point tracking (MPPT), electric losses minimization technique (ELMT), and discontinuous pulsewidth modulation (D-PWM) features. The target is the development of a highly efficient wind generation unit with high dynamic performance, which is able not only to rapidly track the maximum generable power according to any wind speed variation but also to minimize, at the same time, the converters and the machines losses. The proposed wind generator (WG) is based on a back-to-back power converter topology with two voltage source inverters and contains previously developed neural-based MPPT, as well as an original version of an ELMT. The proposed wind generation unit has been experimentally tested on a suitably developed test set-up. Results clearly show that the integration of ELMT+D-PWM into the MPPT-based WG control permits the active power injected into the power grid to be increased up to 37.5% at high wind speeds and up to 240% at low wind speeds.

EMI Analysis in Electrical Drives Under Lightning Surge Conditions

In this paper, a complete model of a power drive system including the earth electrodes is proposed to evaluate electromagnetic conducted interference due to lightning pulses. Circuit model of a power drive system is joined with a full-wave approach for the simulation of the time behavior of the grounding system. The proposed model enables to predict the electromagnetic conducted interference generated in the power drive system when lightning conditions involve the earth electrodes.

EMI Reduction in DC-Fed Electric Drives by Active Common-Mode Compensator

A novel common-mode (CM) EMI active filter for dc-fed motor drives is proposed. The active filter performs both the compensation of the CM voltage at the motor input and the mitigation of the leakage high-frequency CM currents, thus increasing the drive reliability and the vehicle electromagnetic compatibility (EMC). The filter scheme is based on a voltage feedback action and also includes a feed-forward action by exploiting a suitably estimated CM current. An optimized design of the CM voltage detection/injection systems is implemented. Moreover, the active filter is supplied by a smaller voltage than the dc link value; this permits a more performing amplifier to be used. The active filter behavior is analyzed theoretically and its performance is assessed by experiments. The realized prototype shows a good efficiency and compactness.

Benchmarking of PWM techniques effects on efficiency, power quality and EMI in DC-supplied induction motor drives

In this paper several Pulse Width Modulation (PWM) techniques are implemented and experimentally compared to benchmark their impact on efficiency, Power Quality and EMI of Voltage Source Inverters (VSIs) for DC supplied induction motor drives used in building and land or sea vehicular applications. In particular, both continuous and discontinuous PWM methods have been addressed and experimentally tested.

Parameter Identification for Photovoltaic Source Models

Several methods for PV model parameter extraction are addressed in this chapter with reference to static models. The considered identification methods are mainly based on analytical or numerical solutions and use either the rated data given by the manufacturer or the experimental data directly measured at the PV source. A simplified method based on the experimental measurement of the remarkable points is also proposed. The possibility to simplify the parameter identification by using linear regression methods is explored and some hints on the PV characteristic determination by mapping techniques are given. The PV models, suitably identified, are finally implemented in Matlab/Simulink® environment and simulation results are shown.

Translation of the Single-Diode PV Model Parameters Identified by Using Explicit Formulas

Recent literature proposes some approaches that employ explicit equations for identifying the five parameters of the single-diode model describing a photovoltaic (PV) panel. These methods avoid the iterative solution of a nonlinear system of equations, whose convergence is very sensitive to the guess solution. Therefore, they are particularly suitable to perform parameter identification in real time and to be implemented on low-cost, low-performance processing platforms. In this paper, the applicability of some explicit methods, previously validated under standard test conditions, is analyzed for a large class of panels under operating conditions that are different from the standard ones. The study considers both a consolidated method for translating the PV model parameters as well as a novel approach. The analysis allows assessing the most suitable parameter translation equations for each considered explicit identification method, highlighting the effectiveness of such explicit approaches under different operating conditions. An in-depth validation based on experimental data concerning two commercial PV panels corroborates the analysis.

A growing neural gas network based MPPT technique for multi-string PV plants

This paper presents a maximum power point tracking (MPPT) method founded on the integration of a model-based technique given by a growing neural gas (GNG) network and a perturb and observe (P&O) algorithm. The neural network is trained off line to estimate the solar irradiance and the maximum power point starting from a measurement of voltage and current on the photovoltaic source. A variable step size perturb & observe method is then utilized to track the true maximum power point. The method is set up for a DC/DC boost converter used in a multi-string PV architecture. The voltage control of the DC/DC converter is performed by a fuzzified PI, assuring the best dynamic performance and stability of the system in all working conditions.

Electrical Loss Minimization Technique for Wind Generators Based on a Comprehensive Dynamic Modeling of Induction Machines

This paper proposes a novel model-based electrical loss minimization technique (ELMT), whose main original contribution lies in the overall power loss function which has been derived from a comprehensive dynamic space-vector model of the induction machine (IM) including the iron losses, expressed in the rotor flux-oriented reference frame. Such a loss formulation, obtained from the IM input–output power balance, is more general and accurate than the others in the literature; consequently, the expression of the optimal efficiency reference flux to be given to the field-oriented system is more general and accurate too. The proposed ELMT has been integrated into an IM-based wind generation system including a previously developed maximum power point tracking based on a growing neural gas artificial neural network. The obtained results show that the new formulation of the overall power losses of the IM leads to an increase of the IM efficiency with respect to the classic loss equation proposed in the scientific literature. The integration of the proposed ELMT in a real wind generation system leads to an increase of the active power injected into the grid ranging from 33% at high wind speeds up to 200% at low wind speeds.

Input EMI filter re-design in AC motor drives with active compensation of motor CM voltage

This paper deals with the design of the input EMI filter in an AC motor drive when the compensation of common mode emissions towards the motor is performed by an active filter. Both the drive and the active filter have been analyzed through an high frequency circuit model in order to identify the main propagation loops for CM disturbance. In particular the EMI emissions towards the grid are evaluated also in comparison with those generated in a configuration without the active filter. The accuracy of the model has been assessed by experimental measurements. Results show a reduction of CM EMI towards the grid in the lower frequency range of conducted emissions when the active filter is installed. This demonstrates that EMC requirements compliance of the drive can be achieved with a reduction in the size of the input EMI filter.