Search

In this paper, we present a predictive control algorithm that uses a state-space model. Based on classical control theory, an exact discrete-time model of an induction machine with time-varying components is developed improving the accuracy of state prediction. A torque and stator flux magnitude control algorithm evaluates a cost function for each switching state available in a two-level inverter. The voltage vector with the lowest torque and stator flux magnitude errors is selected to be applied in the next sampling interval. A high degree of flexibility is obtained with the proposed control technique due to the online optimization algorithm, where system nonlinearities and restrictions can be included. Experimental results for a 4-kW induction machine are presented to validate the proposed state-space model and control algorithm. Index Terms--Induction motor drives, predictive control, state-space methods.

The use of an inverter with an output LC filter allows for generation of output sinusoidal voltages with low harmonic distortion, suitable for uninterruptible power supply systems. However, the controller design becomes more difficult. This paper presents a new and simple control scheme using predictive control for a two-level converter. The controller uses the model of the system to predict, on each sampling interval, the behavior of the output voltage for each possible switching state. Then, a cost function is used as a criterion for selecting the switching state that will be applied during the next sampling interval. In addition, an observer is used for load-current estimation, enhancing the behavior of the proposed controller without increasing the number of current sensors. Experimental results under linear and nonlinear load conditions, with a 5.5-kW prototype, are presented, verifying the feasibility and good performance of the proposed control scheme. Index Terms--Power conversion, predictive control, uninterruptible power systems.

This paper presents a detailed description of Finite Control Set Model Predictive Control (FCS-MPC) applied to power converters. Several key aspects related to this methodology are, in depth, presented and compared with traditional power converter control techniques, such as linear controllers with pulsewidth-modulation-based methods. The basic concepts, operating principles, control diagrams, and results are used to provide a comparison between the different control strategies. The analysis is performed on a traditional three-phase voltage source inverter, used as a simple and comprehensive reference frame. However, additional topologies and power systems are addressed to highlight differences, potentialities, and challenges of FCS-MPC. Among the conclusions are the feasibility and great potential of FCS-MPC due to present-day signal-processing capabilities, particularly for power systems with a reduced number of switching states and more complex operating principles, such as matrix converters. In addition, the possibility to address different or additional control objectives easily in a single cost function enables a simple, flexible, and improved performance controller for power-conversion systems. Index Terms--Adjustable-speed drives, current control, model predictive control (MPC), power converters, pulse-width modulation (PWM).

Predictive control algorithms have been proposed for power electronic converters, featuring a high performance in terms of dynamic behavior. This is true due mainly to the accurate modeling and the finite set of inputs or possible switching combinations. However, when it is used in multilevel converters, the dynamic performance is degraded, because the optimization algorithm needs to evaluate and search over a large number of possible switching combinations. In this paper, a predictive control algorithm, which exhibits high dynamic performance for multilevel converters, is proposed. The algorithm reduces the complexity of calculations and the number of possible combinations, allowing the use of predictive control with a large number of switching states. Experimental results on a 27-level asymmetric multicell converter, which validate the proposed algorithm, are presented. Index Terms--Asymmetric multicell inverters, multilevel converters, predictive control.

Predictive control is a very wide class of controllers that have found rather recent application in the control of power converters. Research on this topic has been increased in the last years due to the possibilities of today's microprocessors used for the control. This paper presents the application of different predictive control methods to power electronics and drives. A simple classification of the most important types of predictive control is introduced, and each one of them is explained including some application examples. Predictive control presents several advantages that make it suitable for the control of power converters and drives. The different control schemes and applications presented in this paper illustrate the effectiveness and flexibility of predictive control. Index Terms--Drives, power electronics, predictive control.

This paper presents a new control scheme for an active front-end rectifier using model-based predictive control. The control strategy minimizes a cost function, which represents the desired behavior of the converter. Future values of currents and power are predicted using a discrete-time model. The active and reactive powers are directly controlled by selecting the optimal switching state. The main advantages of this method are that there is no need of linear current controllers, coordinates transformations or modulators. The rectifier operates with sinusoidal input currents and unity power factor. Simulation and experimental results are presented to verify the performance of the proposed power control scheme. Index Terms--AC-DC power conversion, power control, predictive control.

This paper presents a modified predictive current control strategy which allows one to have control over the spectrum of the load current. The proposed method uses a model of the system to predict the behavior of the current for each possible voltage vector generated by the inverter. For that purpose, at each sampling interval, signal predictions are evaluated using a cost function that quantifies the desired system behavior. The cost function used in this work evaluates the filtered error of the load currents. The inclusion of a filter for the load error allows one to manipulate current spectra. Thus, by designing this filter appropriately, the load spectrum can be shaped. The performance of the proposed control strategy is verified by simulation and experimental results. Index Terms--Current control, frequency control, frequency domain analysis, inverters, predictive control.

A new predictive strategy for current control of a three-phase neutral-point-clamped inverter is presented. The algorithm is based on a model of the system. From that model, the behavior of the system is predicted for each possible switching state of the inverter. The state that minimizes a given quality function 9 is selected to be applied during the next sampling interval. Several compositions of 9 are proposed, including terms dedicated to achieve reference tracking, balance in the dc link, and reduction of the switching frequency. In comparison to an established control method, the strategy presents a remarkable performance. The proposed method achieves comparable reference tracking with lower switching frequency per semiconductor and similar transient behavior. The main advantage of the method is that it does not require any kind of linear controller or modulation technique, achieving a different approach to control a power converter. Index Terms--Current control, DC-AC power conversion, inverters, predictive control, switching frequency, voltage control.

This paper presents a predictive current control method and its application to a voltage source inverter. The method uses a discrete-time model of the system to predict the future value of the load current for all possible voltage vectors generated by the inverter. The voltage vector which minimizes a quality function is selected. The quality function used in this work evaluates the current error at the next sampling time. The performance of the proposed predictive control method is compared with hysteresis and pulsewidth modulation control. The results show that the predictive method controls very effectively the load current and performs very well compared with the classical solutions. Index Terms--Current control, digital control, inverters, predictive control.

This paper presents the application of high-power three-level active-front-end rectifiers to regenerate energy in a downhill conveyor system. The selective harmonic elimination method is used to eliminate harmonics 11 and 13, working with very low switching frequency, where six-pulse harmonic orders 6k [+ or -] 1 are eliminated by the delta-wye connection of the transformer. In this way, the input current at the mains is highly sinusoidal with small harmonics starting at frequencies of order 23 and 25. Resonances have been detected, originated mainly by the capacitances of feeding cables and noneliminated harmonics, which produce high-voltage distortion. Theoretical and field measurements present the problem and the solution by using a specially designed high-pass power filter. Index Terms--Active rectifiers, conveyors, pulsewidth modulation (PWM), selective harmonic elimination (SHE).

This paper proposes a new modulation strategy for multilevel inverters, which selects voltage vectors that generate zero common-mode voltage in the load, working at low switching frequency. Experimental results confirm that the method is highly effective and simple to implement in a modern microprocessor. The voltage distortion (total harmonic distortion), the number of commutations, and the linearity are also studied. Finally, it is concluded that the proposed strategy is highly suited for inverters with a high number of levels. Index Terms--Common-mode voltage, multilevel converter, multilevel inverter, space vector.

Electric mining haul trucks are one of the most challenging applications of power electronics in automotive systems. This paper presents some advances in very-high-power trucks used in copper mines. The special operational and environmental requirements for this application are highlighted. It is established that the use of inverter-fed three-phase induction motors with vector control is the preferred solution to reach the required high starting torque and good dynamic performance required by these vehicles. Packaging is a key issue and special attention is dedicated to the forced-air cooling system, because the air has a high dust level including conductive and corrosive materials. The truck's high-performance electric retarding system is described along with a novel use of trolley lines in a diesel boost mode as a way to increase the power and speed of the truck and reduce fuel consumption. Advanced features like remote monitoring, the use of global positioning systems and Internet diagnostics and troubleshooting are also discussed. The paper clearly shows that modern electric haul trucks are highly sophisticated systems that make full use of advances in modern technologies to increase safety and productivity levels. Index Terms--AC motor drives, automotive electronic systems, electronic packaging, global positioning, power electronics, traction motor drives.