A. Ragusa

Analytical Versus Neural Real-Time Simulation of a Photovoltaic Generator Based on a DC–DC Converter

This paper presents a simulator of a PV (photovoltaic) field where the current-voltage characteristic is obtained either with a fully analytical model or with a numerical model based on a Growing Neural Gas (GNG) Network. The power stage is obtained with a DC-DC buck converter driven by the current-voltage-irradiance-temperature relation of the PV array. The improvements introduced here, respect to previous works, are the following: 1) the mathematical model is given as a continuous surface in the irradiance domain, 2) a relation between temperature and irradiance is obtained by a LSR (Leasr Square Regression) method, 3) the thermal constant of the PV field is introduced, 4) a lower number of neurons is used, 5) a better learning of the data is achieved, 6) an experimental prototype of higher rating has been devised and constructed. For both the approaches a more performing control technique of the converter has been used. Finally a PV simulator prototype is experimentally tested.

An Optimized Feedback Common Mode Active Filter for Vehicular Induction Motor Drives

This paper proposes a common mode (CM) electromagnetic interference active filter devised for application in automotive induction motor drives. The active filter is based on a feedback scheme and it is realized using linear amplifiers. It performs the compensation of the CM voltage at the motor input, allowing an increase of the drive reliability and a reduction of the harmonic content of leakage high-frequency CM currents that affect the vehicle electromagnetic compatibility. A size-optimized layout is proposed and the influence of the power linear amplifier performance on the CM voltage compensation is discussed. General guidelines for the active filter design are given and its experimental implementation is presented. Finally, the filter performance is assessed by simulations and experimental tests.

Power-Loss Evaluation in CM Active EMI Filters for Bearing Current Suppression

This paper is focused on the analysis of the power losses in a common-mode (CM) active electromagnetic-interference filter for induction-motor drives. The studied filter works according to a feedforward voltage-sensing-voltage-compensating scheme; it performs the compensation of the CM voltage at the motor terminals. In this way, the shaft voltage is dramatically reduced and the resulting bearing currents are practically eliminated. The contributions to the total power losses associated to the active filter are assessed with reference to medium-power induction-motor drives with different rated powers and switching frequencies. The single terms of power losses due to each part of the active filter are accounted for, and their dependence on the motor-drive size is addressed. Furthermore, the influence of the active-filter losses on the drive efficiency is evaluated.

Design of Grid-Side Electromagnetic Interference Filters in AC Motor Drives With Motor-Side Common Mode Active Compensation

The aim of this paper is to analyze how the introduction of a motor-side common mode (CM) active filter, in a power drive system, influences the CM disturbance propagation. A circuit model of the whole drive, including the active filter, is used as an investigation tool. The accuracy of all simulated results is validated by experimental measurements. Both the electromagnetic interference (EMI) toward the grid and the internal CM disturbance propagation are analyzed. These phenomena are compared when the power drive system is operated both with and without the active filter at the inverter output. An additional effect of the motor-side CM active filter is a slight reduction of EMI toward the grid at lower frequencies. This condition allows a reduction in the size of the power grid CM EMI filter necessary to achieve electromagnetic compatibility requirements compliance for the drive.

Effects of Common-Mode Active Filtering in Induction Motor Drives for Electric Vehicles

This paper deals with the active common-mode (CM) voltage compensation in an induction motor drive where the inverter is supplied by a dc source, which is typical of vehicle applications. The CM voltage at motor terminals, creating a shaft voltage through the motor air gap with possible rise in bearing current, can endanger motor reliability and reduce its lifetime. Therefore, CM voltage filtering is desirable. On the other hand, the operation of an active filter has an impact on drive efficiency due to its specific losses and can affect the electromagnetic interference (EMI) emissions that are generated by the drive. Such effects are investigated in this paper. A detailed description of a CM active filter (CMAF) is presented. An analysis of the CM voltage and current on the motor ground connection before and after the introduction of the CMAF is performed. The power losses due to the CMAF operation are analyzed and experimentally evaluated. Furthermore, the EMI toward the vehicle dc power supply line is investigated. All phenomena are studied by simulation and experimentally. The simulated results “are obtained developing” a high-frequency circuit model of the drive system, including the CMAF, which is implemented using the PSpice software. To accurately perform the experimental tests, a new dedicated high voltage dual dc line impedance stabilization network (LISN) is designed and set up on purpose. The CMAF is found to be an effective solution for the increase in motor reliability and drive electromagnetic compatibility, and its operation does not significantly reduce drive efficiency. Moreover, the CMAF does not worsen the EMI toward the dc supply line. Therefore, its presence does not imply the need for additional filters with respect to the case where no CMAF is used. Simulated results are in good agreement with the experimental ones, confirming the validity of the proposed modeling of the drive system.

Fuzzified PI voltage control for boost converters in multi-string PV plants

This paper is concerned with the problem of the voltage control in a photovoltaic multi-string technology-based DC/DC boost converter. A new fuzzified PI regulator is proposed in order to adapt the voltage control to the non linear and time variant characteristics of the PV source. In particular the fuzzified PI controller parameters can be modified according to the variation of the system transfer function which is dependent on the actual PV source working point. The proposed solution allows to satisfy the control requirements of the boost converter in terms of stability of the closed loop control with the best dynamics in all possible operating conditions.

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.

A grid-connected system based on a real time PV emulator: Design and experimental set-up

This paper presents a grid-connected PV system where the PV source is replaced by a real time emulator. The PV emulator is based on a DC/DC converter controlled by the pole placement technique according to PV current-voltage characteristics. These characteristics are obtained by an analytical model whose parameters are identified on the basis of an actual PV installation. In the proposed plant the power conditioning system is given by a boost converter whose control is based on a fuzzified PI regulator. The DC bus is connected to the grid by a three phase voltage oriented controlled (VOC) active rectifier. The use of the emulator allows to accurately investigate the whole PV system behavior, in every potential working condition, without the use of a real outdoor installation, thus reducing the time and the cost of the experiments. The design and the experimental set-up of the proposed PV system is described in details. Finally experimental test results are given.

Common mode EMI propagation in high voltage DC supplied induction motor drives for electric vehicles application

This paper presents a method for evaluating and predicting the common mode (CM) EMI propagation in high voltage DC-supplied induction motor drives. This configuration represents a typical example of propulsion drive for electric vehicle (EV) applications. In such a drive system the CM currents could have very long transmission routes, leading to radiated EMI noise with potential interference with on board electronic devices. In order to perform an accurate experimental investigations, a new dedicated high voltage (HV) dual DC LISN is disegned and set-up. The CM EMI analysis is performed both in simulation and experimentally. The simulated results are obtained by implementing a high frequency (HF) model of the drive system under study, including the LISN, in a PSpice simulator. The CM currents flowing within the drive system are determined and the CM EMI emissions towards the DC power mains are assessed. Simulated results agree with experimental ones confirming the validity of the proposed modeling of the drive system.

Analytical versus neural real-time simulation of a photovoltaic generator based on a DC-DC converter

This paper presents a simulator of a PV (photovoltaic) field where the current-voltage characteristic is obtained either with a fully analytical model or with a numerical model based on a Growing Neural Gas (GNG) Network. The power stage is obtained with a DC-DC buck converter driven by the current-voltage-irradiance-temperature relation of the PV array. The improvements introduced here, respect to previous works, are the following: 1) the mathematical model is given as a continuous surface in the irradiance domain, 2) a relation between temperature and irradiance is obtained by a LSR (Leasr Square Regression) method, 3) the thermal constant of the PV field is introduced, 4) a lower number of neurons is used, 5) a better learning of the data is achieved, 6) an experimental prototype of higher rating has been devised and constructed. For both the approaches a more performing control technique of the converter has been used. Finally a PV simulator prototype is experimentally tested.