This paper presents a new predictive control algorithm for grid-connected current-controlled inverters. The control combines a two-sample deadbeat control law with a Luenberger observer to estimate the future value of the grid currents. The resulting control offers robustness against the computational delay inherent in the digital implementation and considerably enhances the gain and phase margins of the previous predictive controls while maintaining the high-speed response typical of the deadbeat controllers.

A Robust Predictive Current Control for Three-Phase Grid-Connected Inverters

This paper proposes an analytical procedure for computation of all pairs of valid switching angles used in pattern generation in five-level H-bridge cascaded inverters. The proposed procedure eliminates harmonic components from inverter output voltage and, for each harmonic, returns the exact boundaries of all valid modulation index intervals. Due to its simple mathematical formulation, it can be easily implemented in real time using a digital signal processor or a field-programmable gate array. In this paper, after a detailed description of the method, simulation and experimental results demonstrate the high quality of achievable results.

Analytical Method for Pattern Generation in Five-Level Cascaded H-Bridge Inverter Using Selective Harmonic Elimination

This paper proposes a modified stationary reference frame-based predictive current controller with zero steady-state error for LCL coupled inverter-based distribution generation systems. Analytical expressions for the predictive current control error sources are investigated. The stability margin for the predictive current gain is derived. Online adaptive control for the grid voltage is embedded in the control system to eliminate steady-state real and reactive power errors. The grid voltage estimation expressions for sensorless operation are employed to enhance system robustness and performance. Finally, simulated and practical results verify the derived expressions and the proposed control system performance.

A Modified Stationary Reference Frame-Based Predictive Current Control With Zero Steady-State Error for LCL Coupled Inverter-Based Distributed Generation Systems

Carrier modulation is the most common method for inverter control of ac drive systems Operation at switching frequencies of several kilohertz is customary to restrain the harmonic distortion of the motor currents Lower switching frequency is preferred for medium-voltage drives, owing to the higher switching losses of the semiconductor devices This calls for optimizing the performance of the pulsewidth modulator Improvements are achieved by abolishing carrier modulation with its equidistant time spacing of the voltage pulses Optimal pulse patterns can be precalculated for every steady-state operating point of the drive The patterns are stored in a memory of the drive system, from which they are retrieved and used for inverter control Control at transient operation is achieved by adapting the optimal steady-state pulse patterns to the respective situation Specific trajectories of the motor current space vector are then created by online optimization An alternative method of online optimization relies on predicting the space vector trajectories for the next possible inverter switching states The switching state that leads to minimum switching frequency is then selected Optimal pulsewidth modulation reduces harmonic distortion It permits operation at very low switching frequency and reduces the switching losses This increases the current-carrying capability of the semiconductor devices to the extent that the power rating of an inverter approximately doubles

Optimal Control of Medium-Voltage Drives—An Overview

Many different types of electric vehicle (EV) charging technologies are described in literature and implemented in practical applications. This paper presents an overview of the existing and proposed EV charging technologies in terms of converter topologies, power levels, power flow directions and charging control strategies. An overview of the main charging methods is presented as well, particularly the goal is to highlight an effective and fast charging technique for lithium ions batteries concerning prolonging cell cycle life and retaining high charging efficiency. Once presented the main important aspects of charging technologies and strategies, in the last part of this paper, through the use of genetic algorithm, the optimal size of the charging systems is estimated and, on the base of a sensitive analysis, the possible future trends in this field are finally valued.

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Electric Vehicles Charging Technology Review and Optimal Size Estimation

In view of the GA-BP neural network model for estimating the state of charge (SOC) of batteries be greatly influenced by the voltage sampling accuracy. Here, a SOC estimation model based on fuzzy weighting algorithm is proposed which is modified by combining GA-BP neural network with ampere integration method. In addition, the block diagram of the fuzzy weighted SOC estimation model and the specific design process of the model and the determination of input and output and the formulation of fuzzy rules are given here. Through comparing the simulation of SOC model based on GA-BP neural network with the simulation of SOC fuzzy weighting algorithm model based on GA-BP neural network and ampere integral method, it is concluded that the SOC fuzzy weighting algorithm studied here is superior to the SOC algorithm based on GA-BP neural network.

Research on SOC fuzzy weighted algorithm based on GA-BP neural network and ampere integral method

A predictive current control for three-phase PWM rectifiers is proposed to simplify the design of the current loop with less memory and interrupt resource occupation in a digital signal processor. Together with the decomposition-matrix method, the total algorithm can be completed with only one timer and its underflow interrupt subroutine. The predictive current controller helps to design the voltage regulator and make the input currents track the input voltages so well that high power factor is achieved. Finally, the experimental results are given to verify the proposed predictive current control.

Design and Analysis of Three-Phase Reversible High-Power-Factor Correction Based on Predictive Current Controller

A novel single-stage three phase high power factor converter based on three-level zero-voltage soft-switching circuit is proposed, which can much better cancel off the limitation of high voltage rated switches needed in the conventional three phase power factor corrector with single switch if high power factor is wanted. In addition, double-current rectifier is employed in three-level zero-voltage soft-switching circuits so that zero voltage switching in a wide of load range is much more easily achieved compared to conventional circuit. And no duty-cycle-ratio loss and no voltage spike at DC side in this proposed topology. In this paper, The operation principle of this circuit is analyzed and relational curves between high power factor and parameters are provided, and the transfer gain of output voltage to input peak voltage, computation formula of input boost inductances and output filter inductors are deduced. Finally, simulation and experimental results are given in this paper.

Zero-Voltage-Switching Three-Level Three-Phase-High-Power-Factor Rectifier

It will be one of the most important content to take the electric vehicle batteries as distributed energy storage units which can accept the power dispatching, and now bidirectional charger is the key power electronic device that has been used to connect power grid to the electric vehicle battery. In this paper, a two-stage bidirectional power converter made up of T-type neutral point clamped (NPC) three-phase three-level (TL) AC/DC and dual active bridge (DAB) DC/DC is studied, And the direct power control strategy is adopted to accept power dispatching from power grid. With high reliability, efficiency and high power quality as the goal, a novel space vector modulation (SVPWM) is proposed to avoid the terminal voltage distortion of bridge legs, and the series-parallel-connection DAB converter is presented to further improve efficiency. Finally, experimental results verify the feasibility of circuit topology and control strategy.

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Study on bidirectional-charger for electric vehicle applied to power dispatching in smart grid

A novel algorithm for space vector pulse width modulation in three phase power factor correction applications is proposed. The durations for the active vectors that formed the sector containing the desired reference voltage vector are calculated directly by matrix pre-decomposing, without looking up sinusoidal and tangential tables, based on TMS320F240. Therefore running speed and control precise of the program can be improved greatly. As a result the switching frequency and power density of the rectifier is increased considerably. A new method for detecting sector is given as well. Simulated and experimental results are provided to verify the proposed algorithm in the end of the paper.

Yu Fang

Papers

Research on SOC fuzzy weighted algorithm based on GA-BP neural network and ampere integral method

Design and Analysis of Three-Phase Reversible High-Power-Factor Correction Based on Predictive Current Controller

Zero-Voltage-Switching Three-Level Three-Phase-High-Power-Factor Rectifier

Study on bidirectional-charger for electric vehicle applied to power dispatching in smart grid

A fast algorithm for SVPWM in three phase power factor correction application