Indirect predictive control techniques for a matrix converter operating at fixed switching frequency

The following paper presents a novel indirect model predictive control strategy for a direct matrix converter (DMC). The direct matrix converter has a large number of available switching states and therefore the implementation of predictive control techniques require high computational resources. In addition, the simultaneous selection of weighting factors for the control of input and output variables of the converter complicates the system tuning. In this paper, two indirect model predictive control strategies are proposed in order to reduce the computational cost and by doing so avoid the use of weighting factors. The proposal is enhanced with a fixed switching frequency strategy in order to improve the performance of the full system. Results confirm the feasibility of the proposal by demonstrating that it is an alternative to classical predictive control strategies for the direct matrix converter.CONACYT – Consejo Nacional de Ciencia y Tecnologí

An Overview of Microgrids Challenges in the Mining Industry

Indexación: Scopus.The transition from fossil fuels to renewable energies as power sources in the heavy industries is one of the main climate change mitigation strategies. The carbon footprint in mining is related to its inherent extraction process, its high demand of electric power and water, and the use of diesel. However, considering its particular power requirements, the integration of microgrids throughout the whole control hierarchy of mining industry is an emergent topic. This paper provides an overview of the opportunities and challenges derived from the synergy between microgrids and the mining industry. Bidirectional and optimal power flow, as well as the integration of power quality have been identified as microgrid features that could potentially enhance mining processes. Recommendations pertaining to the technological transition and the improvement of energy issues in mining environments are also highlighted in this work.https://ieeexplore.ieee.org/document/9229426

Preselection algorithm based on predictive control for direct matrix converter

This paper presents an enhanced predictive control strategy to reduce the calculation effort for direct matrix converters. The main idea is to preselect the switching states to decrease the calculation effort during each sample period. The proposed preselection algorithm enables a predefined cost function to consider only the preselected switching states to perform the expected control. On the basis of the preselection of switching states at each sample period, the proposed method can effectively reduce the calculation effort as well as show a good performance. The proposed predictive control scheme using only preselected switching states needed to generate the desired source/load current waveforms and control the input power factor. The feasibility of the proposed method is experimentally verified and results are presented in the paper

4MW Class High Power Density Generator for Future Hybrid-Electric Aircraft

This paper describes the underpinning research, development, construction and testing of a 4MW multi-three phase generator designed for a hybrid-electric aircraft propulsion system demonstrator. The aim of the work is to demonstrate gravimetric power densities around 20 kW/kg, as required for multi-MW aircraft propulsion systems. The key design choices, development procedures and trade-offs, together with the experimental testing of this electrical machine connected to an active rectifier are presented. A time-efficient analytical approach to the down-selection of various machine configurations, geometrical variables, different active and passive materials and different thermal management options is first presented. A detailed design approach based on 3D Finite Element Analysis (FEA) is then presented for the final design. Reduced power tests are carried out on a full scale 4 MW machine prototype, validating the proposed design. The experimental results are in good agreement with simulation and show significant progress in the field of high power density electrical machines at the targeted power rating

Predictive Control for An Active Magnetic Bearing System with Sensorless Position Control

Active Magnetic Bearing (AMB) technology is becoming attractive for several reasons such as friction-free suspension and high-speed operation, high reliability, and vibrations exemption. These desirable features come at the cost of an increased complexity of the system, which includes position sensors, a power electronic converter and a control system dedicated to the AMBs. This paper focus on the control system design of an AMB featuring a Wheatstone bridge winding configuration. To achieve a high-bandwidth current control able to generate the desired forces, a Finite Control Set Model Predictive Control (FCS-MPC) has been proposed in this paper. The proposed FCS-MPC includes an estimation of the AMB coils inductance, which can be used to improve the control system performance and, at the same time, provide a rotor position estimation without the need of additional sensing coils and possibly without the use of conventional position sensors. The AMB is modelled considering finite element simulation results in order to evaluate the relation between coil inductance variation and rotor position. A standard PI position control is also included in the system. Finally, the control system is validated through simulation

Moving discretised control set - Model predictive control for dual-active-bridge

In many DC/DC converters applications, classical proportional-integral control is often considered. However, when complex converters structures, such as Dual Active Bridge converters, are considered, several challenges may be faced in the control design. In fact, achieving an accurate Dual Active Bridge model may be complex, considering that the small signal model of the circuit varies according with its operating mode. Moreover, Dual Active Bridge converters usually requires a robust control design, due to their high input/output voltage ratio and power level. In order to address these issues, a Moving Discretized Control Set - Model Predictive Control is introduced. The proposed control can achieve faster dynamics and stable operation throughout the power and terminal voltage ranges, considering global control parameters. It also presents a fixed switching frequency with low computational burden, due to the use of only two prediction horizons. Experiments on a 20kHz 1kW Dual-Active-Bridge converter are carried out to verify the effectiveness of the proposed control technique. © 2020 IEEE

Three-port energy router for universal and flexible power management in future smart distribution grids

Nowadays the interest in active networks is significantly growing as a result of the larger diffusion of renewable energy sources and distributed generation systems connected to the grid. The possibility of installing in key points of these modern smart networks devices capable of intelligent energy routing and power flow control, is highly desirable in this scenario. Multilevel power converters and, in particular, Cascaded H-Bridge converters allow the required flexibility, availability and reliability to be considered as a building block for active nodes for the future electrical grid. This paper proposes a 3-port multilevel power converter capable of behaving as a network active node and demonstrates all its capabilities of energy routing and control under different operative conditions

Model Predictive Control for Isolated DC/DC Power Converters with Transformer Peak Current Shaving

In this paper a Model Predictive Control, suitable for isolated DC/DC power converters and featuring optimization on converter operations, is proposed. The control is designed based on a specific a current-fed DC/DC converter topology, named Active-Bridge-Active-Clamp converter. This topology is particularly suitable for batteries interface, utilizing its interleaved structure in order to achieve an effective current ripple cancellation at the low voltage terminals. However, the increased complexity of the ABAC converter requires a specific modulation implementation and a detailed converter modeling. For such reasons, the operating principle of the ABAC converter is firstly introduced and mathematical models of the ABAC are developed in this paper. Subsequently, a Model Predictive Control is proposed and implemented aiming to achieve terminal current regulation, improve dynamic performance and reduce current stress in a wide DC voltage operating range, whilst maintaining a fixed switching frequency and a reduced prediction horizon. Simulation results for a 10kW ABAC converter are provided to validate the theoretical claims. © 2018 IEEE

Predictive control of an indirect matrix converter operating at fixed switching frequency and without weighting factors

In this paper a predictive control technique for an indirect matrix converter is proposed. The control strategy allows the output current control and the instantaneous reactive input power minimization of the converter without any weighting factor in the controller and, at the same time, the operation at fixed switching frequency. Simulation results validate the proposal under both steady and transient states. © 2015 IEEE

Finite Set Model Predictive Control with a novel online grid inductance estimation technique

This paper presents a novel finite control set Model Predictive Control (MPC) approach, for grid connected converters. The advantage of using MPC for this application lies in the fact that it does not require cascaded control loops, PWM modulators or PLLs. However, the supply impedance is generally unknown causing remarkable errors in the MPC control action, in the case its value is not negligible compared to the converter inductance. This paper presents a novel idea for estimating the supply inductance, based on the difference between the grid voltage magnitudes at two consecutive sampling instants. The grid voltage magnitudes are calculated on the basis of the supply current and converter voltage directly within the MPC algorithm, in order to achieve a fast estimation and integration between the controller and estimator. The proposed method is verified via simulation tests on a three-phase two level active front-end