Dead Beat Research Articles

Analysis and Design of PI Plus Repetitive Control for Grid-Side Converters of Direct-Drive Wind Power Systems Considering the Effect of Hardware Sampling Circuits

In inverters based on a single proportional-integral (PI) or deadbeat (DB) controller, an inherent resonance peak may emerge near their current loop cut-off frequency, which results in harmonic amplification or even resonance. Additionally, inappropriate filter circuits implemented in sampling circuits may result in the expansion of the resonance peak. Thus, this paper further investigates the influence of the sampling circuits on a PI- or DB-based control loop. Then, the RC filter in the sampling circuit is designed to reduce the inherent resonance peak. Moreover, a compound control strategy based on an improved repetitive controller (IRC) plus a PI controller is adopted for the grid-side converter of a direct-drive wind system. This strategy enhances the harmonic and reactive compensation performance by reconstructing the internal model of the classic repetitive controller (CRC) and limiting the bandwidth of the PI-based loop to a low level. The parameters of the presented IRC-plus-PI control are designed for the purpose of resonance peak elimination and system stability. Furthermore, the non-integer delay problem is solved with an inserted fraction compensator (FC), which plays the role of a low-pass filter in the IRC. Finally, the feasibility and effectiveness of the presented control method is verified by the experimental results.

A Simple High-Performance Current Control Strategy for V2G Three-Phase Four-Leg Inverter With LCL Filter

Electric vehicles (EVs) can behave as distributed energy storage devices for providing on-demand smart grid support service, that is, an emerging vehicle-to-grid (V2G) technology. A high-performance and easy-implementation current control strategy for V2G three-phase four-leg inverter with LCL filter is proposed. It consists of a deadbeat (DB) controller and a paralleled repetitive controller (RC). The DB controller is based on the weighted average inductor current (WAIC) scheme, which simplifies the third-order LCL filter to be an equivalent first-order $L$ filter. The stability of the DB-controlled inverter with the unmodeled system time delay is analyzed. The DB controller is of very fast response and easy implementation but is not immune to system time delay and various uncertainties. To overcome the disadvantages, a plug-in RC is added to reinforce the DB controller to remove harmonic distortion from the feed-in current in the presence of parameter uncertainties. A lab prototype of 10-kW grid-connected three-phase four-leg inverter has been built up to validate the proposed current control strategy. The simulations and experiments are provided to demonstrate the validity of the proposed control strategy.

Experimental verification of a hybrid control scheme with chaotic whale optimization algorithm for nonlinear gantry crane: A comparative study

This paper proposes an experimental verification of a hybrid partial feedback linearization (PFL) and deadbeat (DB) control scheme as in Hamdy et al. (2018) with chaotic whale optimization algorithm (CWOA) for a nonlinear gantry crane (GC) system. The PFL linearizes the nonlinear model to end up with a linear closed-loop system. The DB controller is utilized for the desirable accelerated response without any oscillation or undesirable effects on the internal dynamics stability. The CWOA is used to tune the controller parameters. A sliding-mode observer (SMO) is utilized to estimate the unmeasured states. Using this hybrid scheme, a better payload sway elimination can be obtained. Finally, the experimental results are presented to illustrate the efficiency and the effectiveness of the proposed scheme with a comparative study.

A Hardware-in-the-Loop Realization of a Robust Discrete-Time Current Control of PMa-SynRM for Aerospace Vehicle Applications

The hardware-in-the-loop (HIL) realization platform significantly supports the advance of control techniques in secure, precise, and low-cost design. Innovative control techniques are anticipated to ensure aerospace vehicle drive controllability. This paper presents a novel robust discrete-time (RDT) predictive current control (PCC) strategy of a permanent-magnet-assisted synchronous reluctance motor (PMa-SynRM) implemented using the HIL tool and the experimental setup. The proposed RDT controller has a discrete-time integral term added to the conventional deadbeat (DB) current predictive control to improve the robustness and stability of the current control. The PMa-SynRM mathematical model with parameter uncertainties is theoretically derived. Conventional PCC techniques are constructed utilizing the DB framework. Although this controller has a good dynamic response, it still suffers from unmodeled transient changes as well as parametric motor uncertainties. A 6-kW PMa-SynRM machine drive system is built and tested using DS1104 R&D Controller Board. Typhoon HIL is used to emulate the PMa-SynRM and the inverter connected to a dSPACE MicroLabBox. The performance of the proposed RDT technique is assessed and compared with traditional DB using the HIL and experimental results under different speed commands, electrical and mechanical motor parameters variations, and rated speed reversal conditions.

Efficient Direct-Model Predictive Control With Discrete-Time Integral Action for PMSGs

This paper presents an efficient direct-model predictive control (EDMPC) technique for surface-mounted permanent-magnet synchronous generators (PMSGs) in variable-speed wind energy conversion systems. The proposed control technique is based on directly computing the reference voltage vector (VV) from the demanded currents using a deadbeat (DB) function. Then, a discrete-time integral action (DTIA) is added to this DB function to enhance the robustness of the proposed EDMPC scheme against variations of the machine parameters and to achieve a good steady-state response. The proposed DTIA is simple and easy to implement. Finally, according to the location of this reference VV, two evaluations of the quality function are only required. Accordingly, the proposed EDMPC technique with DTIA overcomes the following drawbacks of the conventional direct-model predictive control (DMPC): high calculation burden, sensitivity to parameters mismatches, and non-zero steady-state error. The performance of the proposed EDMPC technique with DTIA has been experimentally investigated and compared with that of the EDMPC with time delay control approach and with the performance of the convention DMPC using a $\text{14.5}\,\text{kW}$ PMSG.

Small Signal Model of Voltage Source Converter using Dead Beat Current Controller

Background/Objectives: This study developed a new complete small signal model of VSC (Voltage Source Converter) using Dead Beat (DB) current controller with purpose of facilitating the small signal stability analysis of power system. Methods/Statistical Analysis: The small signal model development is presented step by step including the derivation of the entire system equations, they established in MATLAB m-file and verified by PSCAD simulations. Findings: As the most powerful tool for small signal stability analysis, the eigen value or transfer function technique is widely employed in modern power system analysis. However, it is only valid for a Linear Time Invariant (LTI) system. Recently the Dead Beat (DB) current control, which is characterized by relatively high bandwidth and excellent performance under unbalanced operating condition, is found as the best-tailored current control method for grid connected VSC application, specifically some severe operating conditions. Application/Improvements: In the simulation studies both of the large signal and small signal models are verified for every individual system components, as well as the entire integrated VSC system. It is demonstrated that the study can provide the foundation for outer loop controller design and small signal stability analysis. Keywords: Dead Beat (DB) Control, Linear Time Invariant, Proportional Integrator (PI) Control, Proportional Resonant (PR) Control, Voltage Source Converter

Analysis of an H∞ Robust Control for a Three-Phase Voltage Source Inverter

Recently, power quality improvement has gained a lot of attention due to the rapidly increasing use of power electronics equipment. Several control strategies for DC/AC Voltage Source Inverters (VSI) have been developed to obtain good quality output with low harmonic distortion. This paper proposes a robust control scheme to improve the power quality of a three-phase DC/AC VSI. The control scheme includes an outer voltage loop and an inner current loop, with both controllers designed by the standard H∞ robust control technique. The system with the proposed controller has a low total harmonic distortion (THD) and improved power quality of output voltage in the presence of linear and non-linear loads. The simulation is carried out in MATLAB/Simulink environment, and the results of the proposed control scheme are compared with the performance of dead-beat (DB) predictive control and conventional proportional integral (PI) control. It is observed from the results that the proposed control scheme outperforms other control schemes in terms of the THD level, having a better steady-state and transient performance.

Current Control Method in Doubly Fed Induction Generator Under Low Switching Frequency

The present current control method in doubly fed induction generator cannot realize the segmented grid-connected current control, it’s hard to effectively control the current in doubly fed induction generator. Therefore, a current control method in doubly fed induction generator under low switching frequency is proposed in this paper. Which means to build a mathematical model of the doubly fed induction generator under low switching frequency to analyze the parameters of doubly fed induction generator filter. Then the parameter values of the filter can be obtained. The current in generator can be predicted by adopting the double-sampling predict method. And the current control in generator can be improved according to dead beat control. Then the on-line identification of current parameters by least square method is needed to finish the current control method in doubly fed induction generator under low switching frequency. The experimental results show that the proposed method realized the segmented grid-connected current control in doubly fed induction generator.

Robust Predictive Control for Direct-Driven Surface-Mounted Permanent-Magnet Synchronous Generators Without Mechanical Sensors

In this paper, an extended Kalman filter (EKF) is employed to estimate stator currents, rotor speed, rotor position, and mechanical torque of a direct-driven surface-mounted permanent-magnet synchronous generator (PMSG) based variable-speed wind turbine systems controlled by a robust predictive deadbeat (DB) algorithm. Therefore, the flux-oriented control of the PMSG is realized without mechanical sensors (i.e., no position encoders or speed transducers). The estimated stator currents are fed back to the prediction model in order to compensate the one-step delay caused by the digital controller and to reduce the total harmonic distortion of the stator currents. Thus, the torque ripples are also reduced. Furthermore, a simple disturbance observer is presented, which estimates the perturbations caused by parameter variations of the PMSG or by any unmodeled dynamics in order to enhance the robustness of the proposed DB algorithm. The proposed scheme is experimentally validated using a 14.5-kW PMSG and a dSPACE DS1007 real-time platform. Its performance is compared with that of the conventional DB control strategy for all operation conditions and under parameter variations of the PMSG.

Deadbeat control for a single‐phase cascaded H‐bridge rectifier with voltage balancing modulation

The model predictive control (MPC) is a promising control method for cascaded H-bridge (CHB) rectifiers. One well-known MPC method is the finite-control-set MPC (FCS-MPC). However, three main issues arise in FCS-MPC: heavy computational burden, low steady-state performance, and time-consuming tuning work of weighting factor. Here, an alternative MPC method, deadbeat (DB) control with a capability of voltage balance, has been proposed for a single-phase CHB rectifier. The proposed method is based on the DB solution to obtain zero current error at the sampling instant and the use of a redundancy-based modulation strategy for voltage balance, leading to the ease of controller design and elimination of tuning work. The proposed method has been evaluated against FCS-MPC method on a single-phase three-cell CHB rectifier. The experimental results show that a reduced computational burden, an improved steady-state performance, and a comparable dynamic response can be achieved in the proposed method in comparison with FCS-MPC method.

Dead‐beat regulation of mechanical juggling systems

AbstractIn this paper, mechanical systems subject to impacts and contacts, that would be not controllable if the impacts were absent (usually called jugglers), are considered. On the basis of an algorithm taken from the literature and of a new procedure to determine a reference trajectory for such a class of systems, a fully algorithmic procedure, able to compute a control input that achieves dead–beat regulation of the “uncontrollable” subsystem just by using impacts, is given. Such a procedure exploits some tools borrowed from algebraic geometry that allow to solve parametric systems of equalities and inequalities. A practical example of application of the given procedure is reported.

Deadbeat Model-Predictive Torque Control With Discrete Space-Vector Modulation for PMSM Drives

This paper proposes an alternative strategy of finite-control-set model-predictive torque control (MPTC) to reduce the computational burden and the torque ripple and decouple the switching frequency from the controller sampling time. An improved discrete space-vector modulation (DSVM) technique is utilized to synthesize a large number of virtual voltage vectors. The deadbeat (DB) technique is used to optimize the voltage vector selection process, avoiding enumerating all the feasible voltage vectors. With this proposed method, only three voltage vectors are tested in each predictive step. Based on the improved DSVM method, the three candidate voltage vectors are calculated by using a novel algebraic way. This new strategy has the benefits of both the MPTC method and the DB method. The effectiveness of the proposed strategy is validated based on a test bench.

Enhanced DBCC for high‐speed permanent magnet synchronous motor drives

High bandwidth and accuracy of the current control loop are fundamental requisites when a fast torque response is required or for facilitating the reduction of torque ripple in high performance drives, especially at high speed. One of the most suitable control methods to achieve these goals is dead beat current control (DBCC). Many types of DBCC have been proposed and implemented in literature. This paper proposes a DBCC incorporating two new functionalities. One is a two steps current prediction to improve prediction accuracy when current measurements are taken place before each sampling period; and particularly to reduce the overshoot during transients when mean value is used as current feedback. The second is a novel compensation method for the rotor movement to eliminate offset errors which occur at high speed. Moreover, the dynamic and steady state performance of the proposed DBCC is assessed in simulations. On the basis of the simulation tests, the control parameters are tuned for experiments and the performance of the proposed functionalities are verified. Finally, the advantage of DBCC, compared with a classical dq PI current regulator, is verified in experiments.

Efficient Implicit Model-Predictive Control of a Three-Phase Inverter With an Output LC Filter

Three-phase inverters with an output LC filter are commonly used to provide sinusoidal voltages with low-harmonic distortion. Constraint on peak filter current is often desirable to protect the components from potential damage. In case of constraints, implicit and explicit model-predictive control (MPC) are some of the feasible controller options. The conventional implicit MPC requires a large number of computations, whereas explicit MPC cannot directly incorporate real-time changes in model parameters, while still being computationally expensive than some of the other control schemes, e.g., hysteresis, dead beat control, etc. In this paper, we propose a new approach to solve the optimization problem in implicit MPC that has a computational complexity approximately five times less than that of explicit MPC. We have been able to achieve lower computational requirements by exploiting the inverter model and the structure of constraints.

A new approach to study the coexistence of some synchronization types between chaotic maps with different dimensions

When synchronizing chaotic systems, an interesting phenomenon that may occur is the coexistence of several synchronization types. Referring to discrete-time chaotic (hyperchaotic) systems, this paper presents a new approach to rigorously study the coexistence of some synchronization types between maps with different dimensions. By exploiting a Lyapunov-based approach, the paper first analyzes the coexistence of full state hybrid projective synchronization and generalized synchronization when the drive system is a three-dimensional map and the response system is a two-dimensional map. Successively, the coexistence of three different synchronization types is illustrated, i.e., inverse projective synchronization, inverse generalized synchronization and Q–S synchronization are proved to coexist between two-dimensional drive systems and three-dimensional response systems. Finally, by exploiting a pole placement technique, the coexistence of antiphase synchronization and dislocated full state hybrid projective synchronization is proved to be achieved between three-dimensional drive system maps and two-dimensional response system maps. Since synchronization is achieved in finite time, this last case represents an example of dead beat coexistence of some synchronization types in maps with different dimensions. Several numerical examples of coexistence of synchronization types are illustrated, with the aim to show the effectiveness of the novel approach developed herein.

Simplified fault tolerant finite control set model predictive control of a five-phase inverter supplying BLDC motor in electric vehicle drive

Multiphase brushless direct current (BLDC) motors can meet the increasing demand for higher reliability in motor drives applicable in electric vehicles by integrating fault diagnosis to a fault-tolerant (FT) control method. To achieve this goal, a modified FT finite control set model predictive control (FCS–MPC) is proposed in this paper. The dead beat control is used to predict the reference voltage applied by the inverter. A sensitivity analysis is done to show the effect of model uncertainty on the controller performance. In addition, a simple, fast and general open switch and short circuit fault detection (FD) method in voltage source inverter (VSI) is presented. The FD method is capable of detecting open switch, open phase, and short circuit faults without any auxiliary variable. Moreover, it is robust to both speed and load transients in a motor drive. To validate the presented theory, experimental results are conducted on a five-phase BLDC motor drive with outer rotor in wheel structure.

Finite-Control-Set Model Predictive Torque Control With a Deadbeat Solution for PMSM Drives

This paper proposes a control strategy of finite-control-set model predictive torque control (FCS-MPTC) with a deadbeat (DB) solution for permanent-magnet synchronous motor drives. By using a DB solution, the process of selection of the best switching vector is optimized. The predicted DB voltage sector consisting of the desired voltage vector (VV) avoids the complete enumeration for testing all feasible VVs, which relieves the big calculation effort of the traditional FCS-MPTC method. The proposed system is experimentally carried out both in the steady state and in the transient state.

Novel optimal control strategy for power fluctuation and current harmonic suppression of a three-phase photovoltaic inverter under unbalanced grid faults

Summary Under unbalanced grid faults, the output currents of a photovoltaic (PV) system injected into the grid lose their sinusoidal and balanced appearance. The interaction between such unbalanced currents and voltages leads to fluctuations in active and reactive powers. This study investigates the instantaneous output power characteristics of a PV inverter and its flexible power control strategy under unbalanced grid faults. A new optimal parameter model of power control is established to generate minimal integrated power fluctuations under the constraint of harmonic distortion in the output current. Finally, the optimal power control of the PV inverter based on dead beat current tracking is realized. The feasibility of the proposed control strategy is verified with the power system transient software PSCAD/EMTDC. Copyright © 2015 John Wiley & Sons, Ltd.

Repetitive Control in the Applications of H-Bridge Active Power Filter

In order to improve the deficiency of the traditional repetitive control, a novel control method combining dead beat control and repetitive control in series is proposed to improve the dynamic performance of the control system. A low-pass filter on the delay link of repetitive control is added to solve the contradiction between repetitive control stability and steady-state accuracy, while the compensation link is designed with the combination of leading phase and the low-pass filter to reduce the control object by relying on accurate mathematical model. The control method, on the basis of steady state accuracy, improves the relative speed and compensation accuracy. The feasibility of the proposed method is verified by the experimental design. DOI: http://dx.doi.org/10.11591/telkomnika.v11i7.2838 Full Text: PDF

분산전원용 계통연계형 PCS의 전류제어기 비교

In this paper, three current controllers for a grid-connected PCS using an LCL filter are compared and analyzed. Current controllers discussed in this paper are linear controllers such as PI (proportional-integral), PR (proportional-resonant), and DB (deadbeat) controller. Both transient and steady state responses of each controller are compared through both simulation and experiment. Although the DB controller has the fastest transient response and the lowest THD in the steady state, the DB controller has two cycles delay of current response in the steady state and has the stability problem which can be occurred due to variation of the system parameters. On the one hand the responses of PR controller are not much different from that of DB controller but the other hand that are not only strong to noise of grid current but also have smaller THD than PI controller. Considering the response time and stability issue of three controllers, the PR controller has the best performance among three controllers and thus can be strongly recommended as a current controller for a grid-connected PCS.