Deadbeat Control Research Articles

Investigation on Multisampling Deadbeat Current Control With Time-Delay Compensation in Grid-Connected Inverter

The control of voltage source converters (VSCs) is now implemented on digital microprocessors. This digitalization has the drawback of time delay in the control loop. The goal of this research work was to investigate improvements that can be obtained from the combination of model-based and model-free time-delay compensation approaches. Deadbeat control (DBC) from model-based techniques and the method of moving the control variable’s sampling instants, or the pulse-width modulation (PWM) updating instants, from model-free time-delay compensation techniques, were put together as the proposed new method of time-delay compensation in this study. These controllers were thoroughly examined in terms of control algorithm design, system stability analysis, and sensitivity analysis of plant parameter perturbations. In addition, thorough Simulink-based computer simulations were conducted in this work to assess the performance of each controller. The proposed method compensated about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$80~\mu \text{s}$ </tex-math></inline-formula> as compared with the time delay compensated by the conventional single-sampling method. This research work was limited to simulations only; hence, conducting experiments to further validate this research work could be a direction for further research.

Modified Deadbeat Predictive Current Control Method for Single-Phase AC–DC PFC Converter in EV Charging System

In a single-phase charging system of electric vehicles, the current control performance of the single-phase ac–dc factor correction (PFC) converter with a deadbeat predictive current control (DPCC) method is affected by the distorted grid voltage, parameter dependence, and control delay. To tackle these problems, a modified DPCC method is proposed in this article. By introducing a phase adjustment parameter <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">θ</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> , which can be directly calculated according to the required power factor, into the grid voltage feedforward of the current loop, an improved input current control performance with lower harmonic components and higher power factor can be achieved when the converter operates at unity power factor. At the same time, compared with the traditional method, a reactive power compensation function is added in the modified DPCC and a deadtime compensation method is adopted in the modulation. Finally, a 7.8-kW single-phase PFC converter prototype is built to verify the feasibility and effectiveness of the proposed control method.

Direct Deadbeat Control of a Buck PWM Converter

The paper explains the shortcomings of the well-known modal control strategy, which prevent its practical application to achieve the highest possible dynamic performance of switching semiconductor converters. A method for eliminating these shortcomings is suggested as applied to a self-contained modal control version with specifying zero roots of the characteristic polynomial and obtaining a nilpotent system matrix. A technique for synthesizing direct deadbeat control with a nilpotent system matrix is described in detail to implement a finite transient that terminates within a number of cycles not exceeding the order of the difference equation with which a discrete system is described. The control object is a well-known circuit of a DC-DC buck converter with an inductive-capacitive filter and a proportional input-output characteristic provided by an integral link in the feedback loop. The efficiency of the proposed deadbeat controller version is confirmed through mathematically simulating the operation of a PWM converter controlling the load current. The dynamic operation modes are studied for the case of a step change in the load resistance and input voltage relative to their nominal values for a control system with I-, PI- and deadbeat controllers. A comparison of the obtained results shows that the transients in the system equipped with a deadbeat controller terminate most quickly: within three cycles without an overshoot. This corresponds to the maximum convergence rate to the equilibrium state for a third-order system.

Wide Frequency PWM Rectifier Control System Based on Improved Deadbeat Direct Power Control

The precision of deadbeat direct power control depends on the parameters of the system model. In wide frequency applications, such as multi- electric aircraft and electric vehicles, variations in frequency and resistive parameters will affect the control effect. The AC side voltage frequency of the generator rectifier varies widely, which will lead to a steady-state reactive power error in the deadbeat direct power control. In addition, the large temperature variation range during the operation of the multi-electric aircraft and electric vehicles leads to large changes in the filter inductance and line resistance of the AC side, and the model parameters do not match the actual parameters, which will further deteriorate the control accuracy. In this paper, a PWM rectifier control method is proposed for the occasions when the frequency and temperature change are in a wide range. Using repetitive control and power compensation, it solves the problems of steady-state reactive power error and control accuracy degradation caused by the mismatch of model parameters under severe operating conditions. The control method can precisely adjust the output DC voltage of PWM rectifier, and it also can maintain unity power factor and reduce the total harmonic distortion rate of the input current. The effectiveness of the proposed control method is verified by the experimental results.

Modeling and Suppression of Circulating Currents Among Parallel Single-Phase Three-Level Grid-Tied Inverters

T-type three-level inverters have attracted extensive attention for their utility in many applications, especially photovoltaic power generation. For these inverters, parallel operation offers superior performance in capacity, reliability, and scalability. However, the introduced circulating current (CC) may cause overcurrent in line, which seriously threatens the safety and stability of the system. The mechanism of CC lacks detailed analysis in single-phase modular inverters. Thus, an accurate mathematical model is established and a CC suppression method is proposed in this article for parallel-operated single-phase T-type three-level inverters. First, the characteristics of port degradation are analyzed, and an improved equivalent circuit is introduced based on the findings. Then, according to the improved equivalent circuit, a detailed mathematical model is established. Using this model, excitation sources of CC are analyzed and divided into three parts. After that, a CC suppression method involving carrier-based pulsewidth modulation with offset voltage injection is proposed, and a deadbeat controller is designed to calculate the offset voltage. Moreover, the proposed method can balance the neutral-point voltage across dc-link capacitors as well. Simulation and experimental results validate the theoretical analysis and effectiveness of the proposed scheme.

Transient Performance Improvement of Deadbeat Predictive Current Control of High-Speed Surface-Mounted PMSM Drives by Online Inductance Identification

This article presents an analytical derivation of transient performance deterioration for high-speed surface-mounted permanent magnet synchronous machine (SPMSM) drives under parameter mismatches, with an advanced deadbeat predictive current control (DBPCC), which exhibits fast dynamics and strong robustness with disturbances rejection. All the influential factors, including permanent magnet flux linkage and inductance mismatches, inverter nonlinearity, and speeds are taken into account in the analysis. It is shown that the transient performance with the advanced DBPCC is only dependent on inductance accuracy. Large transient overshoot and cross-coupling in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> -axis currents at high speeds arise due to inductance mismatch. Based on the understanding gained through the analysis, a novel inductance identification method is also proposed in this article, which significantly improves the transient performance of high-speed SPMSM drives. The proposed online inductance identification method does not require signal injection, is nonintrusive, and can be easily implemented. By integrating the proposed method with the advanced DBPCC, the close-to-ideal deadbeat control can be achieved for high-speed SPMSM drives even in the presence of parameter mismatch and inverter nonlinearity. Both the analysis and proposed method have been validated experimentally on a prototype high-speed (30 000 r/min) SPMSM drive under various conditions.

Harmonic Compensation of APF Three-phase Three-line System Based on Quasi-PR Control

The Active power filter (APF) plays an important role in reducing the harmonic distortion rate of grid current and improving grid stability. However, the APF based on traditional methods such as deadbeat control and hysteresis control has poor tracking accuracy for the load harmonic current, and it is difficult to achieve efficient compensation. In this regard, this paper proposes a current inner loop quasi-proportional resonant (PR) control method to achieve fast-tracking of the compensation current and high control precision. Then, according to the equivalent mathematical model of the three-phase APF in the continuous domain, the parameters of the quasi-PR control method are designed. Finally, the effectiveness of the proposed method is verified by simulation.

A Quasi-Resonant Extended State Observer-Based Predictive Current Control Strategy for Three-Phase PWM Rectifier

In this letter, a quasi-resonant extended state observer-based predictive current control (QRESO-based PCC) strategy is proposed for three-phase pulse width modulation (PWM) rectifier. Specifically, the QRESO is utilized to estimate the predictive value of system total disturbance and grid current at time instant <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> +1 in the stationary <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">αβ</i> frame, and the required control input at time instant <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> +1 is then calculated based on the principle of deadbeat predictive control. The proposed control scheme can achieve robust control against to the electrical parameter variation, accommodate the measurement noise, and also assure the satisfactory steady-state and dynamic performance for the PWM rectifier. Besides, the stability analysis of QRESO and the whole current close-loop control system with the consideration of QRESO in the discrete-time domain are presented. Finally, several hardware-in-the-loop test results of the proposed control strategy are provided and compared with the model free predictive current control based on linear extended state observer and the generalized integrator-extended state observer-based PCC strategy, which validate the effectiveness and superiority of proposed QRESO-based PCC strategy.

A Novel Predictive Position Control With Current and Speed Limits for PMSM Drives Based on Weighting Factors Elimination

Conventional predictive position control (PPC) method balances the position, speed and current of permanent magnet synchronous machine with different weighting factors. However, tedious tuning work of weighting factors is needed. To simplify the tuning process, a cost function that includes the system position, and current information is constructed based on deadbeat control method. A novel method based voltage boundary is proposed to limit the current and speed simultaneously, the voltage regions corresponding to current and speed constraints are analyzed and the voltage duty cycle is further modified according to the voltage regions, the complex weighting factor turning work is avoided, the current and speed limits are easy to implement with proposed method and less position error can be achieved. Finally, the proposed method is experimentally compared with a conventional finite-control-set PPC method and a direct speed model predictive control method.

Vector Analysis Based Multiobjective-Modulated Model Predictive Control for Four-Switching-State Multilevel Converters

The article proposes a new vector analysis based model predictive control (VAMPC) method for multilevel converters with four different switch configurations. It is based on track of an error vector using fundamental state vectors, and can achieve deadbeat control of four switching states multilevel converters with multiple control objectives. Compared with conventional finite control set model predictive control (FCS-MPC) method, VAMPC can achieve excellent spectrum characteristics in the case of a slight increase in computational burden. The VAMPC method is experimentally validated on a 100-kHz GaN-based three-level flying capacitor (FC) converter. Compared with the FCS-MPC, VAMPC leads to significant reduction in steady-state control errors. For example, the inductor current total harmonic distortion of the FC converter is now reduced by more than 60%.

Dynamic Enhancement for Dual Active Bridge Converter with a Deadbeat Current Controller.

This paper investigates the deadbeat current controllers for isolated bidirectional dual-active-bridge dc-dc converter (IBDC), including the peak current mode (PCM) and middle current mode (MCM). The controller uses an enhanced single phase shift (ESPS) modulation method by exploiting pulse width as an extra control variable in addition to phase shift ratio. The control variables for PCM controllers are derived in detail and the two different current controllers are compared. A double-closed-loop control method is then employed, which could directly control the high-frequency inductor current and eliminate the transient DC current bias of the transformer. Furthermore, load feedforward was introduced to further enhance the dynamic of the converter. With the proposed control method, the settling time could be reduced within several PWM cycles during load disturbance without transient DC current bias. A 5 kW IBDC converter prototype was built and the settling time of 6 PWM cycles during load change with voltage regulation mode was achieved, which verifies the superior dynamic performance of the control method.

Thrust Ripple Suppression for Linear Induction Machines Based on Improved Finite Control Set-Model Predictive Voltage Control

In this article, two kinds of finite control set-model predictive voltage control (FCS-MPVC) methods have been proposed for linear induction machine to eliminate the cumbersome selection of the weighting factor (WF), achieve lower ripples of both thrust and flux, and reduce the heavy calculation steps. The first method, FCS-MPVC I, uses one voltage vector (VV) during the whole control period, and the second method, FCS-MPVC II, uses two VVs. Moreover, the proposed methods use a single cost function without any WF. This function consists of the errors between primary voltage references with their predicted values in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">αβ</i> -axis. Depending on the distance between the reference VV (RVV), as calculated using the deadbeat control method, and all candidate VVs (CVVs), the first proposed method, FCS-MPVC I, can select the nearest VV to the RVV as the optimal VV (OVV), which can reduce the redundant evaluation work greatly. Meanwhile, the second proposed method, FCS-MPVC II, applies two VVs, active VV and null VV, to adjust the duty ratio effectively. To avoid the iterated evaluation for all CVVs, one simplified search order excluding unsuitable CVVs has been proposed to determine the optimal OVV, which selects only one active VV from the two adjacent active VVs in the sector owning the RVV. Afterward, based on a prototype of 3-kW arc induction machine with a large radius, extensive simulation and experiments have fully demonstrated that the proposed methods can get much lower thrust ripples and less calculation steps effectively, compared with those of conventional finite control set-model predictive thrust control strategy.

Fast Hands-Off Control Using ADMM Real-Time Iterations

We investigate the implementation of a sparsitypromoting hands-off control scheme using the alternating direction method of multiplies (ADMM). In order to minimize the numerical control effort along with the actuation one, only a single ADMM iteration per time step is considered. We analyze the resulting closed-loop dynamics for linear systems with additive disturbances and show that the proposed scheme provides sparse controls as desired and, in addition, ensures input-to-state practical stability. We further point out a close relation between the proposed real-time scheme and (nonminimum time) dead-beat control. Finally, characteristics and effectiveness of the novel hands-off controller(s) are illustrated with numerical examples.

Polynomial Estimation of Flux Linkage for Predictive Current Control in PMSM

This article presents an automatic parameter identification method based on ordinary least square (OLS) algorithm for deadbeat predictive current control (DPCC) to fulfill the purpose of high steady and dynamic performance in permanent magnet synchronous motor (PMSM) drives. Different from the conventional model, a novel model based on the polynomial estimation of flux linkage is constructed which takes the cross-saturation effects into account. First, the conventional mathematical model of PMSM and the proposed model are presented, respectively, and the inverter considering nonideal factors is also analyzed. Then the parameter identification method is investigated, in which the measurement procedure is delimited in advance and the automatic identification method is developed. Furthermore, a voltage reconstruction algorithm is applied to solve the inverter nonlinearities and the digital time-delay effect, so as to improve the accuracy of the identified parameters. Accordingly, a novel DPCC algorithm is presented based on the proposed model to achieve better performance. Finally, based on the concept and principles mentioned before, a detailed comparison of the DPCC based on the classical model considering the parameters’ variation and the modified model of the proposed method is carried out on a laboratory prototype.

A Hybrid Two-Stage Control Solution for Six-Phase PMSM Motor With Improved Performance

This article proposes a hybrid two-stage control solution for a six-phase permanent magnet synchronous machine (PMSM) motor with enhanced control performance. The original direct torque control (DTC) and model predictive control (MPC) are artfully integrated together to alleviate the computational burden and the harmonic currents. The proposed method is implemented in two steps. First, the original DTC method is adopted to determine the orientation vector from six existing vectors. It is worthy to mention that the orientation vector is different from the commonly used reference vector calculated through the deadbeat control theory. Second, the prediction vectors located in the same sector with the orientation vector will be evaluated in the original MPC manner. In this way, the enumeration of all the prediction vectors is avoided and the computational burden is avoided. In addition, discrete duty ratios are assigned to define other two groups of virtual vectors to enhance the current quality. In this way, high-performance control of a six-phase motor can be achieved by simply combining the standard DTC and MPC control structure. Experimental results have been used to assess the goodness of the proposed method.

Low complexity duty cycle modulation model predictive current control of permanent magnet synchronous motor

This study proposes a model predictive current control algorithm for the synchronous permanent magnet motor with low complexity duty cycle modulation. Three single-phase voltage vectors are simulated to synthesize the target voltage vector that enables the current to achieve deadbeat control. The algorithm can change the amplitude and direction of the synthesized vector and extend the selection range of the synthesized vector to the whole hexagonal region. That is to say, this method can realize the deadbeat control of the d-axis and q-axis currents, and reduce the current pulsation. Moreover, this method only needs one action time operation, which can directly convert the action time of the voltage vector into a three-phase duty cycle after equivalent processing and over-modulation of the action time of the voltage vector. It is not necessary to traverse multiple sectors for optimization, which simplifies the modulation method and reduces the computational complexity. The effectiveness and reliability of the proposed method are verified by theoretical derivation and experimental results.

Predictive deadbeat average model control for phase‐shifted full‐bridge DC/DC converter

Digital current control method is the mainstream method for high-power DC/DC converters. However, digital controllers require additional filters for noise suppression to ensure their proper operation in the complicated electromagnetic environment. The filtering processes coupled with the inherent time delays of digital systems significantly degrade dynamic performance. Thus, steady-state performance is improved at cost of dynamic performance in conventional current control. To solve the problems, this paper establishes a deadbeat average control model based on application of the oversampling technique for phase-shifted full-bridge (PS-FB) DC/DC converter and proposes a predictive deadbeat average model control method by incorporating predictive control into the proposed control model. Simulation and experimental results verify the effectiveness of the proposed control method in mitigating the contradiction between steady-state performance and dynamic performance in the digital system.

Improved Flux Weakening Control Strategy for Five-Phase PMSM Considering Harmonic Voltage Vectors

This article proposes a novel flux weakening scheme for five-phase PMSM with active harmonic currents injection. The conventional flux weakening control schemes applied in the five-phase PMSM do not consider the voltage limit drop in the fundamental subspace due to the harmonic current controller. Thus, the derivation between the reference current trajectory and actual current trajectory would cause the current distortion when applying deadbeat current controller (DBCC). This article analyses the precise voltage limit circles considering the voltage drop caused by the resistance and harmonic currents control at first. Then, a feed-forward flux weakening control algorithm is designed to optimize the current trajectory online. The gradient descent method is used to ensure the converge speed and stability of the optimized current trajectory. Thirdly, the peak value of phase currents would be clipped by the harmonic currents to prevent the inverter current limit, where a new non-linear harmonic current controller is designed to precisely control the harmonic currents. Finally, the DBCC and modified SVPWM technology are utilized to generate the duty cycle. The proposed improved flux weakening control strategy is successfully implemented in an interior five-phase PMSM, and the performance demonstrate the effectiveness of this strategy.

Three‐vector model predictive power control for three‐level T‐type rectifier based on dead‐beat control

This paper presents a three-vector model predictive power control with neutral-point voltage balance (TVMPPC-NPVB) and a dead-beat control for three-phase three-level T-type rectifier. Three vectors are adopted to reduce the current ripple, balance the neutral-point voltage and achieve unity power factor on the AC side simultaneously, while the conventional model predictive power control suffers from large current ripple, difficulty in designing the weighting factor and computational burden. In the proposed strategy, two cost functions are derived to select the optimal space vector sequence and reduce the computational burden. The action time of each vector is introduced in detail. The traditional PWM rectifier utilizes PI controller to regulate the output voltage. But PI controller tends to have a long transition time and big variation on output voltage when the load changes suddenly. The proposed dead-beat control is capable of solving these problems caused by conventional PI controller. Both simulation and experimental results are shown to confirm the effectiveness of the proposed method.

Resilient Control Under Quantization and Denial-of-Service: Codesigning a Deadbeat Controller and Transmission Protocol

This article is concerned with the problem of stabilizing continuous-time linear time-invariant (LTI) systems subject to quantization and denial-of-service (DoS) attacks. In this context, two DoS-induced challenges emerge in the design of resilient encoding schemes, namely, the coupling between encoding strategies of different signals, and the synchronization between the encoder and decoder. These challenges are addressed by a novel proposed structure based on a deadbeat controller as well as a delicate transmission protocol for the input and output channels, and codesigned leveraging the controllability index. When both input and output channels are subject to DoS attacks and quantization, the proposed structure is shown able to decouple the encoding schemes for input, output, and estimated output signals. This property is further corroborated by designing encoding schemes as well as conditions ensuring exponential stability of the closed-loop system. On the other hand, when only the output channel is subject to network attack phenomena, the proposed structure can achieve exponential stabilization without acknowledgment (ACK) signals, in contrast to existing ACK-based results. Finally, a numerical example is given to demonstrate the practical merits of the proposed theoretical and practical approach.