Umberto Abronzini

Steady-State Dead-Time Compensation in VSI

The performance of Voltage Source Inverter (VSI) is affected by power semiconductor nonlinearities, dead time, and control delay. The compensation of these nonlinear effects is necessary to meet requirements in terms of current quality and high efficiency, especially for grid-connected power conversion systems. In this paper, the effects of nonlinearities are widely analyzed and a new compensation technique for a steady-state current-controlled VSI is proposed. It is based on a step-by-step voltage compensation on the basis of the current error evaluated within each control interval. As a result, a complete compensation is achieved within a whole period of the fundamental. To cope with the zero-current clamping effect, the proposed compensation technique is implemented in a recursive way. For slow-dynamic applications, such as photovoltaic systems, this method allows achieving high performance with very low computational requirements.

Dead time and non-linearities compensation for CHB multi-level converters with integrated ESS feeding EV's ultra-fast charging stations

This paper deals with a compensation technique for non-linear behaviour of single phase modular multi-level power converter, feeding electric vehicle fast charging station with split integrated energy storage system. The proposed method calculates the voltage compensation on the basis of the error between the reference and the real currents. It allows highly improving the harmonic content of the grid current in steady-state conditions within a single period of fundamental.

Multi-source power converter system for EV charging station with integrated ESS

This paper deals with the optimal sizing and power flow control for grid-connected multi-source power converter system for EV charging infrastructure with integrated energy storage system. The sizing of the power conversion system is based on cost-benefit analysis which takes into account several factors to define the e-mobility scenario and different topologies of power conversion units. The proposed solution allows minimizing the impact of EV charging processes on the electric grid as well as their cost by means of suitable use of a renewable source and an energy storage system.

Optimal energy control for smart charging infrastructures with ESS and REG

The adoption of the smart and sustainable charging infrastructures for electric vehicles (EVs) represents a key-point to accelerate the electro-mobility uptake. This paper presents an optimal power flow management for a smart charging micro-grid that minimizes the cost and reduces the impact on the grid of EVs requests. This goal is achieved by means of an optimal integration and control of renewable energy, stationary energy storage system, and V2G into the charging infrastructure. In particular, the optimal power flow management solves a stochastic multilayer optimization problem based on the definition of different priority levels representing the coordination of the ESS with the other sources. The output of the algorithm is the day-ahead prediction of the energy generation and, thus, the optimization of energy flow during the entire day. Possible variation of energy sources during the operation are also taken into account by means of a real time control adaptation.

Dead time and nonlinearities compensation for VSI feeding AC drives

This paper presents a recursive nonideality compensation method for Voltage Source Inverter (VSI) controlled by Predictive Current Control (PCC) in the field of electrical drives. An accurate mathematical model of the effects of VSI nonlinearities, such as dead time and control delay, is here reported including the magnitude loss and the ripple distortion. For every sampling interval, the exact voltage error and ripple time-shift is calculated using only reference and real phase currents. As soon as a steady-state operation is detected, the voltage error of the entire fundamental period is stored in an array and then used to accurately compensate the VSI output voltage in the next fundamental period. The error array is renewed after every transient and a look-up-table is step-by-step built including the motor operating conditions and related voltage error. Experimental and numerical results validate the effectiveness of the proposed algorithm in reducing the VSI voltage and current distortions and their influence on the motor torque and efficiency.