Switching Frequency Reduction Using Model Predictive Direct Current Control for High-Power Voltage Source Inverters
TL;DR: A novel current control approach called model predictive direct current control (MPDCC) is presented, which takes into account the discrete states of the voltage source inverter (VSI), and the current errors are predicted for each sampling period.
Abstract: In this paper, a novel current control approach called model predictive direct current control (MPDCC) is presented. The controller takes into account the discrete states of the voltage source inverter (VSI), and the current errors are predicted for each sampling period. Voltage vectors are selected by a graph algorithm, whereby the most appropriate vector is chosen based on an optimization criterion. However, this depends on whether the state of the system is transient or steady. In the first case, the current error should be minimized as fast as possible in order to obtain fast dynamics. In the latter one, the VSI switching behavior is optimized since the switching losses account for a large amount of the total converter losses in high-power drive systems. MPDCC has been developed for a general neutral-point isolated resistive-inductive load with an internal voltage source. For demonstration, the presented control strategy has been implemented on a small-scale permanent-magnet synchronous machine drive system with a two-level VSI. This new approach has several advantages. The most important one is that the switching frequency is reduced up to 70% compared to linear control combined with pulsewidth modulation. Second, MPDCC obtains fast dynamic responses, which are already known from, e.g., direct torque control.
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TL;DR: The paper shows how the use of FCS-MPC provides a simple and efficient computational realization for different control objectives in Power Electronics.
Abstract: This paper addresses to some of the latest contributions on the application of Finite Control Set Model Predictive Control (FCS-MPC) in Power Electronics. In FCS-MPC , the switching states are directly applied to the power converter, without the need of an additional modulation stage. The paper shows how the use of FCS-MPC provides a simple and efficient computational realization for different control objectives in Power Electronics. Some applications of this technology in drives, active filters, power conditioning, distributed generation and renewable energy are covered. Finally, attention is paid to the discussion of new trends in this technology and to the identification of open questions and future research topics.
1,331 citations
Cites background from "Switching Frequency Reduction Using..."
...In recent years, a considerable effort has been made towards the validation of predictive-based control schemes in power electronics and drives by comparing their performance with that of industry-standard controllers....
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...Other recent applications of MPC in drives aim not only for current or torque control but also other simultaneous objectives such as reducing the switching losses [35], balancing the neutral point potential in NPC inverters [48], [51] and mitigating filter of the nominal load. resonances [52]....
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TL;DR: In this paper, a model predictive direct speed control (MP-DSC) is proposed, which overcomes limitations of cascaded linear controllers and selects plant inputs based on the predicted speed error.
Abstract: Servo drives and drives for position control require a high dynamic on speed control. In this paper, model predictive direct speed control (MP-DSC) is proposed, which overcomes limitations of cascaded linear controllers. The novel concept predicts the future current and speed states in discrete steps and it selects plant inputs which depends mainly on the predicted speed error. Secondary control objectives, such as maximum torque per ampere tracking are included. MP-DSC uses the finite control set approach which makes it suitable for online predictions with a prediction horizon of a few sample periods. The concept has been developed by simulation and evaluated on an experimental test bench. The overall control behavior is evaluated applying reference and disturbance steps to the system, where MP-DSC shows promising results. A solution for disturbance (e.g., load toque) rejection is proposed, and the effectiveness to avoid control offsets is shown. Furthermore, the dynamic performance and the steady-state behavior of MP-DSC is evaluated and discussed.
462 citations
Cites background or result from "Switching Frequency Reduction Using..."
...1) Input Preselection: The possible inputs ue(k) ∈ Ue which can be applied after a given input ue(k − 1) are additionally limited by a switch state graph similar to [15] (see Fig....
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...Moreover, a switching state graph, which is known from model predictive direct current control (MPDCC) [15], [16], has been introduced for keeping the switching frequency of MP-DSC low....
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TL;DR: Experimental results verify that PTC can achieve results similar to FOC, possibly even improving performance in transient conditions, and achieve the fairest possible comparison at steady state.
Abstract: This paper presents a comparative study between field-oriented control (FOC) and Predictive Torque Control (PTC) applied to induction machines. Both strategies are implemented on the same experimental bench and similar tests are performed. Furthermore, they were previously adjusted to get an equivalent switching frequency at a specific operation point, achieving the fairest possible comparison at steady state. Experimental results verify that PTC can achieve results similar to FOC, possibly even improving performance in transient conditions.
430 citations
TL;DR: A composite control method combining the DPCC part and current prediction and feedforward compensation part based on SCDO, called DPCC + SCDO method, is developed and a novel sliding-mode exponential reaching law is proposed to further improve the performance of the proposed current control approach.
Abstract: In order to optimize the current-control performance of the permanent-magnet synchronous motor (PMSM) system with model parameter mismatch and one-step control delay, an improved deadbeat predictive current control (DPCC) algorithm for the PMSM drive systems is proposed in this paper. First, the performance of the conventional predictive current control, when parameter mismatch exist, is analyzed, and then a stator current and disturbance observer (SCDO) based on sliding-mode exponential reaching law, which is able to simultaneously predict future value of stator current and track system disturbance caused by parameter mismatch in real time, is proposed. Based on this SCDO, prediction currents are used for replacing the sampled current in DPCC to compensate one-step delay, and estimated parameter disturbances are considered as the feedforward value to compensate the voltage reference calculated by deadbeat predictive current controller. Thus, a composite control method combining the DPCC part and current prediction and feedforward compensation part based on SCDO, called DPCC + SCDO method, is developed. Moreover, based on conventional exponential reaching law, a novel sliding-mode exponential reaching law is proposed to further improve the performance of the DPCC + SCDO method. Simulation and experimental results both show the validity of the proposed current control approach.
380 citations
Cites background from "Switching Frequency Reduction Using..."
...Predictive current control basically can be categorized into two groups: model predictive control [16], [17] and deadbeat predictive control [4]–[6], [7]....
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TL;DR: A predictive torque and flux control of an induction machine drive fed by a three-phase two-level voltage source inverter is developed and the proposed strategy replaces the single cost function with a multiobjective optimization based on a ranking approach.
Abstract: Finite control set model predictive control is an emerging alternative in the control of power converters and drives. The method allows flexible control schemes with fast dynamics. However, the standard formulation of this type of controllers is based on a minimization of a single cost function. This optimization method requires weighting factors that depend on the system parameters and operating point. The calculation of these factors is achieved through a nontrivial process. In this paper, a predictive torque and flux control of an induction machine drive fed by a three-phase two-level voltage source inverter is developed. The proposed strategy replaces the single cost function with a multiobjective optimization based on a ranking approach. This approach makes the tuning of weighting factors unnecessary for a correct operation. Simulation and experimental results on steady state and dynamic operation are presented to illustrate the good behavior of the drive.
358 citations
Cites background from "Switching Frequency Reduction Using..."
...The use of a single cost function to solve the optimization problem at each sampling time is not the only possible alternative [24], [25]....
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References
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Book•
01 Dec 2001
TL;DR: A standard formulation of Predictive Control is presented, with examples of step response and transfer function formulations, and a case study of robust predictive control in the context of MATLAB.
Abstract: 1. Introduction to Predictive Control. 2. A Standard Formulation of Predictive Control. 3. Solving Predictive Control Problems. 4. Step Response and Transfer Function Formulations. 5. Tuning. 6. Stability. 7. Robust Predictive Control. 8. Perspectives. 9. Case Studies. 10. The Model Predictive Control Toolbox. References Appendices A. Some Commercial MPC Products B. MATLAB Program basicmpc C. The MPC Toolbox D. Solutions to Problems
5,468 citations
"Switching Frequency Reduction Using..." refers background in this paper
...The cost function (also known as quality or decision function) [6] provides the criterion for choosing the appropriate control action....
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...The number of subsequent prediction steps is called the prediction horizon N [6] and is usually limited to a few sampling periods due to the small timescales in power electronic devices....
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TL;DR: In this article, the authors proposed a limit cycle control of both flux and torque using optimum PWM output voltage; a switching table is employed for selecting the optimum inverter output voltage vectors so as to attain as fast a torque response, as low an inverter switching frequency, and as low harmonic losses as possible.
Abstract: New quick-response and high-efficiency control of an induction motor, which is quite different from that of the field-oriented control is proposed. The most obvious differences between the two are as follows. 1) The proposed scheme is based on limit cycle control of both flux and torque using optimum PWM output voltage; a switching table is employed for selecting the optimum inverter output voltage vectors so as to attain as fast a torque response, as low an inverter switching frequency, and as low harmonic losses as possible. 2) The efficiency optimization in the steady-state operation is also considered; it can be achieved by controlling the amplitude of the flux in accordance with the torque command. To verify the feasibility of this scheme, experimentation, simulation, and comparison with field-oriented control are carried out. The results prove the excellent characteristics for torque response and efficiency, which confirm the validity of this control scheme.
3,316 citations
TL;DR: Current control techniques for three-phase voltage-source pulsewidth modulated converters, including bang-bang (hysteresis, delta modulation) controllers and predictive controllers with on-line optimization are reviewed.
Abstract: The aim of this paper is to present a review of current control techniques for three-phase voltage-source pulsewidth modulated converters. Various techniques, different in concept, have been described in two main groups: linear and nonlinear. The first includes proportional integral (stationary and synchronous) and state feedback controllers, and predictive techniques with constant switching frequency. The second comprises bang-bang (hysteresis, delta modulation) controllers and predictive controllers with on-line optimization. New trends in current control-neural networks and fuzzy-logic-based controllers-are discussed, as well. Selected oscillograms accompany the presentation in order to illustrate properties of the described controller groups.
2,086 citations
"Switching Frequency Reduction Using..." refers methods in this paper
...In the presented work, the novel model predictive direct current (dc) control (MPDCC) concept for high-power converters is suggested as an alternative to low-frequency linear current control combined with a modulation scheme (normally, a proportional–integral (PI) controller combined with PWM)....
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...10 are obtained with the cascade PI control with the PWM module....
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...Moreover, if applied to power converters, MPC can either be combined with a modulation scheme (usually pulsewidth modulation (PWM) [9]) or can directly take into account the discrete nature of power electronic devices [10], [11]....
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...The designed control strategy has been tested and compared to PI+PWM control experimentally on a three-pole-pair PMSM....
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...Main emphasis was put on the reduction of the average 0278-0046/$26.00 © 2010 IEEE switching frequency [17] as compared to the PI+PWM concept, whereby a similar current ripple for both models must be achieved....
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TL;DR: 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 are found.
Abstract: 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
1,554 citations
TL;DR: A simple classification of the most important types of predictive control is introduced, and each one of them is explained including some application examples.
Abstract: 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.
1,389 citations