Deadbeat Control Research Articles

A Switched Reluctance Motor Torque Ripple Reduction Strategy With Deadbeat Current Control and Active Thermal Management

This paper presents a switched reluctance motor (SRM) torque ripple reduction strategy with deadbeat current control and active thermal management. In this method, the SRM torque is indirectly controlled by the phase current. A deadbeat current control method is used to improve the SRM phase current control accuracy, so that SRM torque control error can be reduced significantly. According to the online measurement of the power switching device temperature, the switching frequency will be reduced to prevent the SRM power converter from being damaged by over-temperature. The feasibility and effectiveness of the proposed strategy have been verified in both simulation and experimental studies.

Comparative study on predictive dead-beat peak current, valley current and average current control algorithms for phase-shifted full-bridge DC/DC converters

Three types of digital predictive dead-beat current control algorithms (PDB-CCAs) for phase-shifted full-bridge DC–DC converters with peak current, valley current and average current are presented. The PDB-CCAs are derived directly from the switching characteristics and topological structures of the converters. The proposed algorithms can predict the inductor current in the next switching period by sampling the input voltage, output voltage and inductor current in the current switching period. To ensure the stability of the inductor current, the PDB-CCAs result in a greatly improved transient performance, since the inductor current tracks the reference in one switching period or less when a reference perturbation or current perturbation occurs. In addition, although the procedure for deriving the control algorithms is complex, they can be easily implemented by a digital controller after reasonable simplification. Finally, simulation and experimental results are obtained and they agree with the theoretical results, which demonstrate the validity of the proposed PDB-CCAs.

Deadbeat Predictive Current Control for Modular Multilevel Converters With Enhanced Steady-State Performance and Stability

Model predictive control (MPC) methods are popularly employed in modular multilevel converters (MMCs) due to their fast dynamic response and multiobjective control capability. However, they present some inherent problems, such as computational complexity, variable switching frequency, poor steady-state performance, and tedious weighting factor selection. This article develops a deadbeat predictive current control method for MMCs. This method can realize the reference tracking of ac current and circulating current in one sampling period without error, and thus provide a fast dynamic response as conventional MPC methods. Besides, switching state or voltage level evaluation, cost function calculation as well as weighting factor selection are not required. Therefore, it has a very low calculation burden, which is independent of the number of submodules (SMs). Since a modulation stage is utilized, a fixed switching frequency and consequently a satisfactory steady-state performance are obtained. The effects of time delay, parameter mismatch, and SM capacitor voltage ripple on the control algorithm are discussed. Also, the corresponding improvement measures are provided to further enhance the steady-state performance and system stability of MMCs. The effectiveness and performance of the developed control algorithm are verified by experimental results.

Improved Current Control for a Quasi-Two-Level PWM-Operated Modular Multilevel Converter

Quasi-Two-Level PWM Operation of modular multilevel converters enables a significantly smaller amount of installed module capacitance, even with low output frequencies required for machine drives. This article presents an implementation of this operation mode with an improved current control that leads to fast and precise current transitions. The proposed current control combines a deadbeat controller with a simple hysteresis controller that uses a predictive estimation of branch currents, which are both implemented using an FPGA. The enhanced performance of the proposed control is demonstrated by a comparison to the original one. Experimental results on a laboratory prototype prove the feasibility of Quasi-Two-Level PWM Operation as a machine drive and validate the advantage of reduced overvoltages with long machine cables in comparison to those of conventional two-level inverters.

Direct Power Control of Doubly Fed Induction Generator Using Extended Power Theory Under Unbalanced Network

This paper proposes a novel direct power control (DPC) method for the doubly fed induction generators (DFIGs) power control system. The proposed DPC method is based on extended power theory rather than conventional instantaneous power theory. The proposed method calculates the rotor reference voltage based on the principle of deadbeat power control. Then, it synthesizes the rotor reference voltage using space vector modulation (SVM). As a result, the switching frequency is constant, and satisfactory control performance is achieved under both balanced and unbalanced network conditions. This technique achieves the control target of ensuring a constant stator-side active power, constant extended reactive power, and sinusoidal stator currents without power compensation terms or other measures under unbalanced network conditions. Different from other DPC-SVM methods, the phase-locked loop block is eliminated and the whole structure of the control system is simple and easy to use. No parameter needs to be tuned in the proposed method. The effectiveness of the proposed method is validated by the presented simulation and experimental results on a 1.5-kW laboratory DFIG control system.

Bidirectional Three-Level Cascaded Converter With Deadbeat Control for HESS in Solar-Assisted Electric Vehicles

This article presents a deadbeat-based method for the hybrid energy storage system (HESS) in solar-assisted electric vehicles (EVs), using a new bidirectional three-level cascaded (BTLC) converter. Moreover, photovoltaic (PV) panels are also considered in the system, because the proposed method is designed for solar-assisted EV applications to achieve a longer driving range. The proposed BTLC converter can integrate the battery and the supercapacitor as an HESS to effectively mitigate the power mismatch between the PV power generation and the load power consumption for the solar-assisted EVs. The BTLC converter is superior to the conventional parallel-connected bidirectional battery/supercapacitor converters from the perspectives of related component size reduction and control flexibility. To regulate the BTLC converter, a deadbeat-based method is proposed, which can provide the proper power management for the battery and the supercapacitor, and maintain the bus voltage. The design and implementation of the proposed deadbeat-based method are analyzed in detail. A scaled-down prototype of the proposed BTLC converter is built for the experimental verification. The simulation and experimental results are presented and compared to verify the effectiveness of the deadbeat-based method for the HESS with the proposed BTLC converter.

Deadbeat Control for Single-Inductor Multiple-Output DC–DC Converter With Effectively Reduced Cross Regulation

This article presents a deadbeat-based control approach for the single-inductor multiple-output (SIMO) dc-dc converter. The proposed approach contributes to effectively solve the cross-regulation problem by independently regulating different output voltages based on independent load currents. Unlike conventional model-based methods, which require the measurement of load currents, the proposed approach employs output current observers to replace current sensors. Furthermore, it obtains an excellent dynamic and steady-state voltage regulation performances. Details of the proposed controller and output current observer are discussed. For verifying the validity of the proposed approach, simulation and hardware experiments are conducted on a single-inductor dual-output (SIDO) buck converter platform. The corresponding results are analyzed and compared with the performances of the start-of-art methods.

A Novel Coordinated Control Strategy for Energy Storage System in DC Microgrid With Weak Communication

DC microgrid, consisting of renewable energy sources, energy storage systems, and new types of loads like electric vehicles, has gained more and more attention nowadays. Energy storage systems in dc microgrid are required to regulate dc bus voltage as a backup power source at the islanding state while getting charged or discharged corresponding to energy management command at the grid-connected state. However, the dc bus voltage overshoot would occur with weak communication such as low-speed wireless communication and non-real-time network communication because of the large communication delay during the sudden state switching from grid-connected to islanding state. In this article, a novel coordinated control strategy for energy storage systems independent of real-time communication is proposed. With a novel sliding surface as the outer loop and an auto-tuning dead-beat current control as the inner loop, a smooth mode transition can be achieved even with a large communication delay, which means, real-time communication is unnecessary for the mode transitions. Therefore, the high reliance on the real-time communication is overcome with the system reliability enhanced as well. The proposed control strategy is verified by simulation and experimental results on a 450 V–3.5 kW prototype.

Cost function‐based modulation scheme of model predictive control for VIENNA rectifier

Finite control set model predictive control (FCS-MPC) has been widely used in the control of grid-connected converters with the advantages of fast dynamics, multi-objective control, and easy implement. However, the conventional FCS-MPC bears with variable switching frequency, high current ripple and computational burden. An improved current model predictive with the cost function-based modulation scheme (CFM-MPC) is proposed for a three-phase three-level VIENNA rectifier to improve the power quality. First, the mathematical model and voltage vector are given according to the principle of deadbeat control. Then, the voltage vector of different voltage vectors are selected according to the location of the voltage vector reference, and the switching action time of the selected are directly calculated by the inversely proportional with cost function value of the selected vectors. It remains the merits of both the conventional MPC and space vector pulse width modulation schemes to track the optimum voltage vector without increasing the computational burden. Finally, a comparative study with the proposed CFM-MPC and conventional FCS-MPC has been conducted to verify the superiority of the proposed scheme. The results show the proposed CFM-MPC has the advantages of lower power ripple, fixed switching frequency, lower total harmonic distortion and neutral point potential balance.

Deadbeat Control for Hybrid Energy Storage Systems in DC Microgrids

This paper presents a simple and effective deadbeat-based method for hybrid energy storage systems, including batteries and supercapacitors, in dc microgrids. Inheriting from the nature of deadbeat control strategies, the proposed method can generate the optimal duty ratio in one control cycle, so that it can respond faster to the disturbance than various proportionalintegral-based methods in previous works. With an appropriate reference assignment based on the characteristics of batteries and supercapacitors, this method can compensate the transient and steady-state power mismatches in dc microgrids while maintaining an excellent dc bus voltage regulation. Specifically, the high power density feature of the supercapacitor is fully utilized by the proposed method, and the burden on the battery can be relieved for a longer lifespan. A current observer is employed in the proposed method to eliminate the requirement of photovoltaic (PV) and load current sensors to reduce the system cost. A laboratorial setup of a dc microgrid, including the HESS and PV emulator, is built to validate the effectiveness of the proposed deadbeat-based method under various varying conditions in load power consumption, PV power generation, and bus voltage reference. The performance of the proposed method is compared with that of the previous works to show its superiority in dynamic and steady-state responses.

An Improved Deadbeat Control Method for Single-Phase PWM Rectifiers in Charging System for EVs

In single-phase AC charging system for electric vehicles (EVs), the single-phase pulse width modulation (PWM) rectifier with deadbeat predictive current control (DPCC) is characterized by fast current dynamic response and simple algorithm. However, in steady state, the performance of the DPCC is affected by the circuit parameters mismatch and control delay, which will result in the AC side power-factor degradation and the input current distortion. Moreover, the performance of dynamic response to load mutation can be improved, as the traditional DPCC adopted PI controllers in the voltage loop. In this paper, an improved deadbeat control method is proposed. In the current loop, the AC side voltage compensation parameter is proposed to improve the power factor and reduce the total harmonic distortion (THD). The voltage loop uses an active disturbance rejection controller (ADRC), which improves the dynamic performance of the system. The feasibility and effectiveness of the proposed deadbeat control method is verified by simulation and experimental results.

Hybrid railway power quality conditioner based on half‐bridge converter and asymmetric balanced traction transformer with deadbeat current control

AC electrified railway system is a huge single-phase load, which causes significant power quality (PQ) problems to the upstream power grid. Active railway PQ conditioners (ARPQC) have been introduced to overcome the PQ problems. One of the most important complications of the ARPQCs is its high VA rating which entails significant escalation in the price of the conditioner. To mitigate the rating of the ARPQC, a hybrid configuration including an asymmetric balancing traction transformer and a half-bridge railway PQ conditioner (HBRPC) is proposed in this study. The predictive deadbeat current control with low computational burden and fast dynamic response is used to optimise the performance of the HBRPC. Additionally, a PI adaptive gain controller is proposed for DC-link voltage stabilisation, which minimises the negative impact of the voltage control on the current control stage. The feasibility and functionality of the proposed scheme is validated via simulation and experimental results.

Online Current Loop Tuning for Permanent Magnet Synchronous Servo Motor Drives with Deadbeat Current Control

High bandwidths and accurate current controls are essential in high-performance permanent magnet synchronous (PMSM) servo drives. Compared with conventional proportional–integral control, deadbeat current control can considerably enhance the current control loop bandwidth. However, because the deadbeat current control performance is strongly affected by the variations in the electrical parameters, tuning the controller gains to achieve a satisfactory current response is crucial. Because of the prompt current response provided by the deadbeat controller, the gains must be tuned within a few control periods. Therefore, a fast online current loop tuning scheme is proposed in this paper. This scheme can accurately identify the controller gain in one current control period because the scheme is directly derived from the discrete-time motor model. Subsequently, the current loop is tuned by updating the deadbeat controller with the identified gains within eight current control periods or a speed control period. The experimental results prove that in the proposed scheme, the motor current can simultaneously have a critical-damped response equal to its reference in two current control periods. Furthermore, satisfactory current response is persistently guaranteed because of an accurate and short time delay required for the current loop tuning.

Equivalent input disturbance observer‐based ripple‐free deadbeat control for voltage regulation of a DC–DC buck converter

In this research, voltage regulation of a DC-DC buck converter is realised via the ripple-free deadbeat control (RFDBC) with the equivalent input disturbance observer (EIDO). A small-signal state-space model is constructed for the RFDBC design of a converter. Faced with mismatched models, unknown parameter perturbation, and time-varying voltage source and load demands, augmented disturbance state is constructed and extended state observer is utilised to estimate this augmented model accurately. Based on this model, EIDO is proposed to evaluate the equivalent input disturbance affecting on the input channel. Disturbance compensation is analysed in theory, and the simulation model of the proposed EIDO-based RFDBC is created to illustrate the control performance in MATLAB/Simulink. Finally, a LabVIEW-based FPGA experimental rig is set up for the voltage regulation of a DC-DC buck converter. Two other controllers, RFDBC without EIDO and active disturbance rejection control are also designed for performance comparison. The performance comparison result of transient tracking indicates the outstanding characteristics of the proposed controller.

Robust Current Predictive Control-Based Equivalent Input Disturbance Approach for PMSM Drive

The implementation and experimental validation of current control strategy based on predictive control and equivalent input disturbance approach is discussed for permanent magnet synchronous motor (PMSM) control system in the paper. First, to realize the current decoupling control, the deadbeat predictive current control technique is adopted in the current loop of PMSM. Indeed, it is well known that the traditional deadbeat current control cannot completely reject the disturbance and realize the zero error current tracking control. Then, according to the model uncertainties and the parameter variations in the motor, an equivalent input disturbance approach is introduced to estimate the lump disturbance in the system, which will be used in the feed-forward compensation. Thus, a compound current controller is designed, and the proposed algorithm reduces the tracking error caused by the disturbance; the robustness of the drive system is improved effectively. Finally, simulation and experiment are accomplished on the control prototype, and the results show the effectiveness of the proposed current control algorithm.

Design and development of new control technique for standalone PV system

A Sub-Maximum Power Point Tracking (S-MPPT) algorithm improves the performance of Photo Voltaic (PV) systems. This S-MPPT is used in single-phase PV system to test the tracking accuracy and its impact on the consistency of the whole system. Single phase PV Deadbeat Scheduler is proposed in this paper. The Deadbeat scheduler is a linear system. It initializes each initial state of the system to zero in shortest time possible. A single phase PV structure configuration is proposed to decrease the partial shading effect by changing the parameters of S-MPPT control algorithm. Thus, voltage sensor based S-MPPT algorithm through voltage reference control technique with the help of controller is developed for minimizing the tracking time and steady state oscillations. Selection of the objective function to mitigate the drawbacks associated with voltage sensor based algorithm for a decrease in solar irradiance are also demonstrated. The proposed MPPT algorithm with the designed controller is tested for a step change in irradiance from 270 to 480 W/m2 with a perturbation time of 20 ms and ∆V = 0.5 V (perturbation of voltage). From the simulation results, the proposed method with S-MPPT plus deadbeat control algorithm is compared with other existing algorithms.

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.

Multi-Vector-Based Model Predictive Torque Control for a Six-Phase PMSM Motor With Fixed Switching Frequency

This paper proposes a multi-vector-based model predictive torque control with fixed switching frequency for a six-phase permanent-magnet synchronous machine to improve its steady-state performance. First, two active vectors are synthesized in each control period to suppress the stator current harmonics in x-y subspace. For the sake of easy implementation in the real-time system, the vectors are artfully synthesized in two different manners. Second, to achieve the fixed switching frequency, two null vectors are inserted along with the synthesized vector. The duty ratio of the null vectors is determined based on the principle of deadbeat torque control. In the meantime, the synthesized vector and its duty ratio are evaluated simultaneously by the cost function. In this way, the torque ripple can be reduced considerably. Thus, with the proposed method, both the current harmonics and the torque ripple are reduced effectively. Also, the proposed methodology can be readily implemented practically under the constant switching frequency. Finally, the experimentation is carried out to verify the validity of the proposed method.

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 Deadbeat Current Controller of LC-Hybrid Active Power Filter for Power Quality Improvement

In this article, a deadbeat current controller for an LC -coupling hybrid active power filter ( LC -HAPF) is proposed, which can track with the reference compensation current with low steady-state error and fast dynamic response. Moreover, it can lead LC -HAPF to be operating at a fixed switching frequency with low output current ripples, thus reducing the size of the filtering circuit. First of all, the mathematical model of the deadbeat current controller for the LC -HAPF is deduced based on its single-phase equivalent circuit. Then, the closed-loop control block diagram and its $s$ -domain model is proposed and built. After that, the stability issue and parameter design of the proposed deadbeat current controller are analyzed and discussed. Finally, the compensating performance of the deadbeat current controller for the LC -HAPF is verified by simulation and experimental results compared with the conventional hysteresis band pulsewidth modulation (PWM) control, the proportional-integral (PI) control, and the proportional multi-resonant (PMR) control for the LC -HAPF, which shows its effectiveness and superior compensating performances.