Deadbeat Control Research Articles

Data‐driven, robust output regulation in finite time for LTI systems

SummaryIn this paper, a novel data‐driven approach is proposed to obtain output regulation for linear systems in finite time, requiring only limited information about the plant and the exosystem. The resulting regulator is robust because it does not rely on the knowledge of perturbed or even nominal plant parameters. Finite‐time regulation is achieved, combining the use of the external‐model technique with the deadbeat controller design. The core of the method lies in an error‐feedback reset logic for the state of the external model to compensate for the contribution of the exosystem on the plant output response, then an ancillary control law is introduced to steer the error to zero in a preassigned time interval, trading‐off between convergence rate, and control effort.

Predictive Torque Control of Permanent Magnet Synchronous Motors Using Flux Vector

In this paper, an improved predictive torque control without weighting factor is proposed for a voltage source inverter-permanent magnet synchronous motor drive system, which possesses good control performance of torque and stator flux. By investigating the relationship among torque, the reference stator flux amplitude, and the phase angle of the stator flux, the reference stator flux vector is constructed. Then, the reference voltage vector is calculated by the reference stator flux vector based on the delay compensation and the deadbeat control. The extended control set is designed and two generalized base vectors that require further screening are determined based on the position of the reference voltage vector to improve the calculation efficiency. And the duty ratios used for the generalized base vectors are calculated, according to the geometric relations between the generalized base vectors and the reference voltage vector. Finally, by the duty cycle control between two generalized base vectors and between each generalized base vector and zero vector, the candidate vectors are gained and substituted into the cost function only with the flux vector error term. Experiment tests were carried out and the results validated the effectiveness of the proposed method.

Model Predictive Control of High Power Converters and Industrial Drives [Book News

Conventionally, power electronic converters and drives have been controlled by linear single-nput, single-output control loops. Particularly for high-power converters with multiple coupled dynamics and tight operating constraints, model predictive control (MPC) is expected to evolve into the control method of choice. MPC allows one to increase lower the current distortions, reduce the converter hardware, achieve very fast transient responses, and ensure the reliable operation within safe operating area constraints. The first six chapters of this book offer a three phase power electronics, electrical machines, carrier-based pulsewidth modulation, optimized pulse patterns, state-of-the-art art converter control methods, and the principle of MPC. Chapters 7-14 include an in-depth treatment of MPC methods that fully exploit the performance potential of high-power converters. These control methods combine the fast control responses of deadbeat control with the optimal steady-state performance of optimized pulse patterns by resolving the antagonism between the two. Each chapter is supplemented with an adequate well-selected list of recent references at the end. This is a well-written and richly illustrated text achieving a balance between mathematical rigor and physical insight.

A Universal Multiple-Vector-Based Model Predictive Control of Induction Motor Drives

Conventional finite control set-model predictive control (FCS-MPC) applies single voltage vector within each control period. This leads to relatively high steady-state ripples and requires fast sampling rate. Additionally, enumeration-based optimal vector selection is computationally intensive. Recently, double-vector-based schemes have been proposed to improve the steady-state performance of FCS-MPC. However, they are usually complicated in vector selection and duty ratio calculation. In this paper, a universal multiple-vector-based MPC (UMV-MPC) is proposed, which achieves the same performance as the state-of-the-art double-vector-based MPC, but executes in a much more efficient and universal way. Unlike conventional FCS-MPC, enumerating process and state predictions for candidate voltage vectors are not required in the proposed UMV-MPC to select the best voltage vectors. In UMV-MPC, the optimal vectors and duty ratios are directly constructed from deadbeat control (DBC) based on space vector modulation (SVM), which is easy to follow and quick to use. The proposed UMV-MPC is not only more efficient than prior methods, but also reveals the inherent relationship between double-vector-based MPC and DBC with SVM. A comparative study of UMV-MPC and prior double-vector-based MPC is carried out in this paper. The theoretical analysis as well as simulation and experimental tests on a 2.2-kW induction motor drive are demonstrated to validate the effectiveness of the proposed UMV-MPC.

Deadbeat Control Strategy for Circulating Current Suppression in Multiparalleled Three-Level Inverters

This paper proposes a zero-sequence circulating current (ZSCC) control scheme for the multiparalleled three-level T-type inverters (3LT2Is). Based on the analysis with the proposed generalized model of multiparalleled 3LT2Is, it is seen that the ZSCC is influenced by the circuit parameters, duty cycles, and the circulating currents of the l th and first 3LT2I. To mitigate the circulating currents, a deadbeat control strategy for n-paralleled (n≥3) inverters is proposed, which is realized by adjusting the duty cycle of the small vectors in each PWM sampling period. Compared with the conventional PI control method, the ZSCC spike is mitigated with the proposed scheme, thus improving the quality of the output currents. Also, the reliability of the 3LT2Is system is improved because such a scheme only needs the information about the ZSCC and zero-sequence duty ratio in the l th and the first inverter. The proposed method can also be applied to the neutral-point-clamped converters. Simulation and experimental results verify the effectiveness of the theoretical analysis and the proposed method.

Investigation of a delay compensated deadbeat current controller for inverters by Z-transform

In this paper, the delay problem of a deadbeat current control for a single-phase PWM inverter connected to the grid is investigated by applying z-transform. First, the effect of delay during one sampling period is discussed and then a predictive current observer-based controller is considered. The main objective of the control system is that the current has minimum harmonic distortion, and is in phase with the grid voltage. The control system has fast dynamic response when distortion occurs, and is robust against drift in the system parameters; it also places all the system closed-loop poles at the origin of the z-plane. Hence, it can achieve fast dynamic response with low total harmonic distortion, even under nonlinear loads. The simulation results are performed to verify the feasibility of the proposed control strategy.

A hybrid partial feedback linearization and deadbeat control scheme for a nonlinear gantry crane

This paper presents the design of a hybrid partial feedback linearization and deadbeat control scheme for a nonlinear gantry crane with friction to control its position and sway angle. The partial feedback linearization is used to linearize the nonlinear model and to stabilize its internal dynamics. In many crane applications, it's necessary to accelerate the system response. As a result, this will cause oscillation in the position as well as the sway angle. So, the deadbeat controller is added to get the desirable accelerated response without any oscillation or adverse effects on the internal dynamics stability. By using Lyapunov stability method, the proposed scheme is proved to be globally stable, with converging tracking errors to the desired performance. The simulation results are accomplished to evaluate the effectiveness of the proposed scheme and to demonstrate its reliability to control crane systems with comparative results.

A Double Update PWM Method to Improve Robustness for the Deadbeat Current Controller in Three-Phase Grid-Connected System

In the grid-connected inverter based on the deadbeat current control, the filter inductance variation and single update PWM affect the distortion of the grid current, stability, and dynamic of the system. For this, a double update PWM method for the deadbeat current controller in three-phase grid-connected system is proposed, which not only effectively decreases the grid current distortion and control delay, but also improves the system stability and dynamic response speed due to reducing the characteristic root equation order of the closed-loop transfer function. The influence of the filter inductance deviation coefficient on the system performance is analyzed. As a conclusion, the corresponding filter inductance deviation coefficient in the system critical stability increases with increase in the parasitic resistance of the filter inductance and line equivalent resistance and decreases with increase in the sampling frequency. Considering the system stability and dynamic response, the optimal range of the control parameters is acquired. Simulation and experimental results verify the effectiveness of the proposed method.

Performance evaluation of two-vector-based model predictive current control of PMSM drives

Conventional model predictive current control (MPCC) applies only one vector during one control period, which produces large torque and flux ripples and high current harmonics in permanent magnet synchronous motor (PMSM) drives. Recently MPCC with duty cycle control has been proposed to improve the steady state performance by applying one non-zero vector and one null vector during one control period. However, the prior method requires lots of calculations and predictions to find the optimal voltage vectors and calculate their respective duration. Different from prior enumeration-based MPCC, this paper proposes an efficient two-vector MPCC by applying two arbitrary voltage vectors during one control period. The reference voltage vector is firstly calculated based on the principle of deadbeat current control. Two optimal vectors and their duration are then obtained in a very efficient way, which does not require the calculation of current slopes in prior MPCC methods. The proposed method is compared to the state-of-the-art predictive control methods, including conventional MPCC, MPCC with duty cycle control, deadbeat control with space vector modulation (SVM) and modulated model predictive control (M2PC). Both simulation and experimental results prove that the proposed method achieves better steady state performance than conventional MPCC with or without duty cycle and the dynamic response is not degraded. Under the condition of insufficient dc bus voltage, the proposed method outperforms deadbeat control and M2PC by presenting even higher speed range and less torque ripples.

Deadbeat control based on a multipurpose disturbance observer for permanent magnet synchronous motors

Robustness against parameter mismatches and position-sensorless operation are two important research topics for permanent magnet synchronous motor (PMSM) drives. Usually, the existing observers are designed for achieving a specific function. While here, both the above two functions are integrated into the proposed sliding-mode disturbance observer: (i) if a position sensor is equipped, accurate current regulation can be achieved by deadbeat predictive current control despite mismatched motor parameters; (ii) if the position sensor is not equipped but with a good estimation of motor parameters, the observer can serve as a back electromotive force estimator. Then, the rotor position can be extracted for position-sensorless control. Usually, a low-pass filter is required to suppress high-frequency noises in the conventional sliding-mode observer. This inevitably leads to phase delay in the estimation. By comparison, a complex coefficient filter is inherently embedded in the proposed method, which can provide accurate estimation without phase delay or magnitude error. Experimental results obtained from a 2.4 kW PMSM drive platform indicate that high-performance current control can be achieved with good robustness for position sensor-based operation. Also, rotor position can be accurately estimated with good steady and dynamic performance for position-sensorless operation.

A Robust Digital Control Strategy Using Error Correction Based on the Discrete Lyapunov Theorem

This paper presents a robust digital control strategy using error correction techniques to improve the robustness of conventional deadbeat control methods. The proposed control method, based on the discrete converter models, determined control law using an error correction technique based on the discrete Lyapunov stability theorem. The steady-state performance and dynamic response of the presented method was analyzed and verified. The experimental results showed that the method derived in this paper not only offered improved robustness, but also endowed the grid current with lower Total Harmonic Distortion (THD), while still maintaining a fast, dynamic response.

An Improved Deadbeat Control for a Three-Phase Three-Line Active Power Filter With Current-Tracking Error Compensation

An active power filter (APF) plays an important role in compensating the harmonic component of a nonlinear load current. In this paper, deadbeat control (DBC), which has high control performance and fast dynamic response, is used as a current controller for an APF. An improved DBC (Imp_DBC) is introduced to suppress the adverse effect of the current sampling error and to enhance the interference rejection capability of the control system. The characteristics of the conventional DBC and Imp_DBC are analyzed using transfer functions in the discrete-time domain. The robustness of the system is improved with the inductance variation. Specifically, aiming at the dramatic change of the harmonic component of the nonlinear load current, a current-tracking error compensation method is proposed. The phenomena of the upper co-nvex and lower concave in grid current are eliminated. Finally, the experimental setup of three-phase three-line APF is built, and the effectiveness of this method is verified by experiments.

A Dead-Beat Control for Bridgeless Inverter Systems to Reduce the Distortion of Grid Current

This paper proposes a method to reduce the distortion of the grid current using a dead-beat control (DBC) scheme for bridgeless inverter systems. In the case of the general proportional integral (PI) current controller for power factor correction (PFC) scheme, the grid current is generally distorted due to the slow dynamic response of the PI controller. If the bandwidth of the PI controller increases to overcome this characteristic, the system shows a fast dynamic response. However, it becomes unstable as wide bandwidth leads to the control of unnecessary values such as a grid current noise. On the contrary, the proposed PFC-DBC method has a fast response for the reference current and accuracy compared to the conventional PFC-PI method owing to the optimal duty cycle for the next state current. In addition, the proposed PFC-DBC method can operate robust control by using the estimation method for actual filter inductance. Therefore, the proposed method can reduce the grid current distortion. The proposed method is verified through powersim simulations and experiments.

Model Predictive Direct Power Control for Single Phase Three-Level Rectifier at Low Switching Frequency

This paper presents a new model predictive direct power control (MP-DPC) to overcome the drawbacks of model predictive control (MPC) for single phase three-level rectifiers in the railway traction drive system, including huge online calculation, poor power control precision at the low switching frequency and variable switching frequency. To do so, an exact analytical solution of instantaneous power estimation is adopted to predict active and reactive powers in next duty cycle updating interval for achieving the deadbeat control and reducing the predictive error at the low switching frequency (below 1 kHz). The optimal d -axis and q -axis components of input voltage within next duty cycle updating interval of the adopted rectifier in rotating coordinate system are directly calculated by minimizing the cost function. And the optimal drive pulses are generated by pulse width modulation stage in the proposed MP-DPC, other than evaluating cost function for each voltage vector in traditional MP-DPC. Finally, the influence of inductance mismatch on control system is analyzed, and an inductance estimation method is shown to improve the control precision. An experimental comparison with other five different DPC schemes has verified the effectiveness of the proposed MP-DPC scheme.

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.

Robust Deadbeat Control of an Induction Motor by Stable MRAS Speed and Stator Estimation

In this paper, a new sensorless deadbeat control method is proposed. In the deadbeat method, the desired voltage is calculated via the model of the induction motor and inverter (prediction model). This voltage impels the motor to track the references of the torque and flux in the next control interval. Robustness is an important issue about the deadbeat method. Two new techniques are used to reach a robust speed-independent sensorless deadbeat method. A speed-independent model is sued for prediction. Therefore, the estimated speed will not be used in the prediction model. It will reduce the drift error problem. Also, a new adaptive predictive method is proposed for simultaneous estimation of the stator resistance and speed. Only direct-axis equation is used in the adaptive method. This will reduce the calculation burden. The new adaptive function is achieved via the Lyapunov technique. The stability of the multiple-input multiple-output system for simultaneous adaptation is analyzed for the gain design problem. Simulation and experimental results in wide range of speed are depicted in order to verify the proposed method.

Application of Fuzzy Control in a Photovoltaic Grid-Connected Inverter

To realize the maximum power output of a grid-connected inverter, the MPPT (maximum power point tracking) control method is needed. The perturbation and observation (P&O) method can cause the inverter operating point to oscillate near the maximum power. In this paper, the fuzzy control P&O method is proposed, and the fuzzy control algorithm is applied to the disturbance observation method. The simulation results of the P&O method with fuzzy control and the traditional P&O method prove that not only can the new method reduce the power loss caused by inverter oscillation during maximum power point tracking, but also it has the advantage of speed. Inductive loads in the post-grid-connected stage cause grid-connected current distortion. A fuzzy control algorithm is added to the traditional deadbeat grid-connected control method to improve the quality of the system’s grid-connected operation. The fuzzy deadbeat control method is verified by experiments, and the harmonic current of the grid-connected current is less than 3%.

Deadbeat and Hierarchical Predictive Control with Space-Vector Modulation for Three-Phase Five-Level Nested Neutral Point Piloted Converters

Deadbeat and Hierarchical Predictive Control with Space-Vector Modulation for Three-Phase Five-Level Nested Neutral Point Piloted Converters

Experimental verification of Dead-Beat predictive current controller for small power, low speed PMSM

Experimental verification of Dead-Beat predictive current controller for small power, low speed PMSM

On the Sampling and the Performance Comparison of Controlled LTI Systems

In this paper, the impact of the discretization techniques and the sampling time, on the finite-time stabilization of sampled-data controlled Linear Time Invariant (LTI) systems, is investigated. To stabilize the process in finite time, a discrete-time feedback dead-beat controller is designed for the sampled-data system. Checkable conditions on the approximate discrete-time plant model and the associated controller that guarantee the finite-time stabilization of the exact model are developed. The trade-off between the discretization technique, the sampling time and the desired performances is illustrated and discussed. Results are presented through a case study.