A Low-Computational High-Performance Model Predictive Control of Single Phase Battery Assisted Quasi Z-Source PV Inverters

Impedance network inverters are a good alternative for voltage-source and current-source inverters. The shoot-through solution and the boosting capability of such converters make them an excellent solution for photovoltaic (PV) application. Furthermore, energy storage integration in these inverters does not require any additional components in the converter; indeed, a battery can be directly connected in parallel with one of the capacitors of the Z- or quasi Z-network. However, for an optimal control of these converters, complex control and modulation strategies are required. Model Predictive Control (MPC) provides high control performance at the expense of the computational effort. In this paper, a low computational control method where both MPC and proportional resonant (PR) controller are combined, is proposed. This makes the proposed controller perform two iterations only instead of iterating for all the available switching states. As shown in the obtained results, the proposed controller conserves the high performance of the conventional MPC with 50% less computational burden

A predictive control with flying capacitor balancing of a multicell active power filter

Unlike traditional inverters, multicell inverters have the following advantages: lower switching frequency, high number of output levels, and less voltage constraints on the insulated-gate bipolar transistors. Significant performances are provided with this structure which is constituted with flying capacitors. This paper deals with a predictive and direct control applied to the multicell inverter for an original application of this converter: a three-phase active filter. To take advantage of the capabilities of the multicell converter in terms of redundant control states, a voltage control method of flying capacitor is added, based on the use of a switching table. Flying capacitor voltages are kept on a fixed interval, and precise voltage sensors are not necessary. The association of predictive control and voltage balancing increases considerably the bandwidth of the active filter

The Essential Role and the Continuous Evolution of Modulation Techniques for Voltage-Source Inverters in the Past, Present, and Future Power Electronics

The cost reduction of power-electronic devices, the increase in their reliability, efficiency, and power capability, and lower development times, together with more demanding application requirements, has driven the development of several new inverter topologies recently introduced in the industry, particularly medium-voltage converters. New more complex inverter topologies and new application fields come along with additional control challenges, such as voltage imbalances, power-quality issues, higher efficiency needs, and fault-tolerant operation, which necessarily requires the parallel development of modulation schemes. Therefore, recently, there have been significant advances in the field of modulation of dc/ac converters, which conceptually has been dominated during the last several decades almost exclusively by classic pulse-width modulation (PWM) methods. This paper aims to concentrate and discuss the latest developments on this exciting technology, to provide insight on where the state-of-the-art stands today, and analyze the trends and challenges driving its future

A Novel Reduced Components Model Predictive Controlled Multilevel Inverter for Grid-Tied Applications

This paper presents an improved single-phase Multilevel Inverter (MLI) which is conceptualized to reduce power switches along with separate DC voltage sources. Compared with recent modular topologies, the proposed MLI employs a reduced number of components. The proposed inverter consists of a combination of two circuits, i.e., the level generation and polarity generation parts. The level generation part is used to synthesize different output voltage levels, while the polarity inversion is performed by a~conventional H-bridge circuit. The performance of the proposed topology has been studied using s single-phase seven-level inverter, which utilizes seven power switches and three independent DC voltage sources. Model Predictive Control (MPC) is applied to inject a sinusoidal current into the utility grid which exhibits low Total Harmonic Distortion (THD). Tests, including a~change in grid current amplitude as well as operation under variation in Power Factor (PF), have been performed to validate the good performance obtained using MPC. The effectiveness of the proposed seven-level inverter has been verified theoretically using MATLAB Simulink. In addition, Real-Time (RT) validation using the dSPACE-CP1103 has been performed to confirm the system performance and system operation using digital platforms. Simulation and RT results show improved THD at 1.23% of injected current

Predictive current control of asynchronous machines by optimizing the switching moments

In this paper a model-based predictive control (MBPC) scheme for the current control of induction machines is presented. The controller directly selects the optimal switch state of the inverter. The proposed scheme uses a longer prediction horizon and a limited amount of optimal switching instants to reduce the average switching frequency. The next iteration of the MBPC-scheme is performed at the established optimal switching instant, as such suppressing the receding horizon property for short time spans. The proposed method is compared to a more conventional MBPC-scheme with a very short prediction horizon. Both simulations and experiments clearly show a significant reduction in average switching frequency. However, with a reduction in switching frequency the torque ripple is increased. To correctly asses the properties of the different schemes, a key performance indicator is proposed that offers a fair and unbiased comparison in terms of switching frequency and torque ripple

Guidelines for Weighting Factors Adjustment in Finite State Model Predictive Control of Power Converters and Drives

INTERNATIONAL CONFERENCE ON INDUSTRIAL TECHNOLOGY () (.2009.VICTORIA, AUSTRALIA)Model Predictive Control with a finite control set has emerged as a promising control tool for power converters and drives. One of the major advantages is the possibility to control several system variables with a single control law, by including them with appropriate weighting factors. However, at the present state of the art, these coefficients are determined empirically. There is no analytical or numerical method proposed yet to obtain an optimal solution. In addition, the empirical method is not always straightforward, and no procedures have been reported. This paper presents a first approach to a set of guidelines that reduce the uncertainty of this process. First a classification of different types of cost functions and weighting factors is presented. Then the different steps of the empirical process are explained. Finally, results for several power converters and drives applications are analyzed, which show the effectiveness of the proposed guidelines to reach appropriate weighting factors and control performance

Imposed Switching Frequency Direct Torque Control of Induction Machine Using Five Level Flying Capacitors Inverter

The paper proposes a new control structure for sensorless induction motor drive based on a five-level voltage source inverter (VSI). The output voltages of the five-level VSI can be represented by nine groups. Then, the amplitude and the rotating velocity of the flux vector can be controlled freely. Both fast torque and optimal switching logic can be obtained. The selection is based on the value of the stator flux and the torque. This paper investigates a new control structure focused on controlling switching frequency and torque harmonics contents. These strategies, called ISFDTC, indeed combines harmoniously both these factors, without compromising the excellence of the dynamical performances typically conferred to standard DTC strategies. The validity of the proposed control technique is verified by Matlab/Simulink. Simulation results presented in this paper confirm the validity and feasibility of the proposed control approach and can be tested on experimental setup.Peer reviewe

Impact of PWM strategies on RMS current of the DC-link Voltage Capacitor of a dual-three phase drive

The major drawback of usual dual three-phase AC machines, when supplied by a Voltage Source Inverter (VSI), is the occurrence of extra harmonic currents which circulate in the stator windings causing additional losses and constraints on the power component. This paper compares dedicated Pulse Width Modulation (PWM) strategies used for controlling a dual three phase Permanent Magnet Synchronous machine supplied by a six-leg VSI. Since the application is intended for low-voltage (48V) mild-hybrid automotive traction, an additional major constraint arises: the compactness of the drive related to the size of the DC-bus capacitor. Thus, the PWM strategy must be chosen by taking into consideration its impact on both, the motor and the RMS value of DC-bus current