Predictive Current Control Technique Research Articles

Modulated model predictive current control technique for triple‐boost seven‐level switched capacitor‐based inverter topology

SummaryTraditionally, the finite control set‐based model predictive current control technique (MPC2T) inherently wrenches from the variable switching frequency of operation. To obtain the fixed switching frequency of operation, different types of predictive control approaches have been reported in the literature. However, these are complex while going to single‐phase higher‐level inverter topologies and are not to be generalized in a simple manner. In this paper, a new generalized modulated MPC2T has been proposed for single‐phase switched capacitor‐based multilevel inverter (SC‐MLI) topologies. In this technique, the optimum inverter output voltage (O‐IOV) has been generated by nullifying the derivative of the cost function. The normalized O‐IOV is fed to a new single modulating floor function (F2) single carrier‐based pulse width modulation technique. Compared to all routine PWM approaches, this specific F2‐based modulation stage is extremely straightforward even for higher‐level inverter topologies. The sensorless voltage balancing of switched capacitor topologies completely eradicates the need for weighting factors in predictive algorithms. To verify the robustness and performance of the perspicuous proposed technique, the conventional triple boost SC‐MLI topology has been considered and elucidated with the different steady and dynamic operation of results.

An enhanced predictive current control technique for interior permanent magnet synchronous motor drives with extended voltage space vectors for electric vehicles

SummaryPermanent magnet synchronous motors (PMSM) are widely employed in the application of electric vehicles (EVs) due to their simplicity of operation. Model predictive current control (MPCC) is an advanced technique used to control the PMSM owing advantages like multi‐variable cost function and good dynamic performance. Cost function of predictive current control (PCC) does not require the flux weighting factor; hence, it is simple in the selection of suitable voltage vector (VV). The conventional PCC (C‐PCC) applied to interior PMSM (IPMSM) contains more torque and flux ripples as it includes only one set of voltage vectors for all speed ranges. In proposed PCC (P‐PCC), the magnitude and location of voltage vectors is to be selected as large and small VVs to reduce torque ripples. The P‐PCC in this article utilizes two set of extended voltage vectors (large and small VVs) based on the applied speed change in dynamic conditions and hence reduces the ripple content. Incorporating maximum torque per ampere (MTPA) control in this article serves the purpose of optimizing the machine performance. By adding MTPA to the proposed method, it is aimed to enhance the machine performance with less ripples and improved torque response. Simulation results are presented for conventional and P‐PCC to highlight the effectiveness and efficacy of the P‐PCC. The P‐PCC is experimentally verified with 3.7 kW PMSM using d‐SPACE controller.

Modulated model predictive current control technique for single phase nine‐level T‐type packed U‐cell inverter topology

SummaryThis paper proposes a new floor function single carrier‐based modulated model predictive current control technique (FF‐SC‐M2PC2T) by considering conventional nine‐level T‐type packed U‐cell (9L‐TPUC) inverter topology. To get desired peak value of load current with low harmonic distortion, the finite control set‐based model predictive control technique (FCS‐MPCT) has been reported in the literature considering load dynamics and minimization of the cost function. However, inherently it suffers from variable switching frequency (VSF) of operation. To diminish this issue, an M2PC2T has been implemented and it provides a constant switching frequency (CSF) of operation. Especially coming to the modulation stage, most authors generally use level‐shifted pulse width modulation (PWM) techniques which inherently require more carriers, if‐else conditions, and additional logical gate blocks to generate particular level output. Hence, the control complexity increases as going to higher‐level inverter topologies. In this manuscript, a new simple floor function single carrier‐based pulse width modulation (FF‐SC‐PWM) technique has been proposed which applies to any single‐phase switched capacitor type multilevel inverter topology and it can be easily integrated with a predictive control algorithm to regulate the inverter output current (IOC). Finally, to check the effectiveness of the proposed control technique (PCT) in a closed loop, a laboratory prototype has been employed on 9L‐TPUC inverter topology with different static and dynamic case studies considering RL‐Load.

A New Predictive Current Control With Reduced Current Tracking Error and Switching Frequency for Multilevel Inverters

The forward Euler's integration method is widely used to compute the trajectories of the control variables in conventional predictive current control (PCC) techniques. However, the computational error caused by the forward Euler's method proportionally increases with the sampling time. Hence, the current tracking ability of conventional PCC techniques deteriorates when operating with a large sampling time. Furthermore, the conventional PCC methods produce more switching transitions to reduce the current tracking error, thereby leading to a high switching frequency operation. To overcome these problems, Heun's integration method is proposed for the PCC in this article. The proposed method has predictor and corrector stages to minimize the computational error caused by the large sampling time during the prediction process of the control variables. Thereby, the proposed Heun's method-based PCC techniques produce fewer switching transitions to minimize the current tracking error. Consequently, this results in a decrease in switching frequency. The proposed PCC method is applied to a four-level multilevel inverter (4L-MLI). The discrete-time system models are developed using Heun's integration method to implement the proposed PCC. The working philosophy of the proposed method is demonstrated through the dSPACE/DS1103 controlled 4L-MLI laboratory prototype. The experimental performance of the proposed PCC is compared with that of the conventional PCC in terms of average switching frequency, current tracking error, current harmonic distortion, and transient response time.

A new floor function single‐carrier‐based modulated model predictive current control technique for single‐phase PUC5 inverter topology

SummaryIn this paper, a new floor function (F2) single‐carrier (SC)‐based modulated model predictive current control technique (M2PC2T) has been proposed by considering the conventional single‐phase five‐level packed U‐cell (PUC5) inverter topology. Generally, to regulate the output current, the finite control set‐based MPC technique without a modulator inherently operates with variable switching frequency, and it is unsuitable for industrial applications. To alleviate this, authors have implemented M2PC2T, which provides constant switching frequency of operation. In this technique, generally, the predictive algorithm has been integrated with any modulation stage. However, while the implementation of pulse width modulation (PWM) techniques, most authors have used conventional PWM techniques which further increases the control complexity as the level number increases. In this manuscript, a simple and generalized F2‐SC‐PWM technique has been proposed and integrated with the predictive algorithm. This PWM technique implementation process is very simple as compared with all conventional PWM techniques since even if the level number increases, the number of modulating and carrier signals is always only one. Finally, the complete closed‐loop control technique is called a generalized F2‐SC‐M2PC2T which is suitable for all stiff direct current (dc) sources and switched capacitor‐type multilevel inverter (MLI) topologies. The proposed control technique (PCT) has been experimentally verified with different transient and steady‐state case studies by considering resistive‐inductive load.

A new single modulating and single carrier‐based predictive current control technique for single‐phase quadruple boost multilevel inverter topology

SummaryA new floor function single carrier‐based modulated model predictive current control (F2‐SCM2PC2) technique has been proposed in this paper by considering traditional single‐phase quadruple boost switched capacitor‐based multilevel inverter (QB‐SCMLI) topology. Conventionally, the implementation process of single modulating and single carrier‐based pulse width modulation (PWM) techniques are very much complex and finite control set‐based model predictive control (FCS‐MPC) technique inherently operates with variable switching frequency (VSF) operation, which is not suitable for industrial applications. To alleviate the aforementioned issues, a new generalized closed‐loop F2‐SCM2PC2 technique has been proposed. It consists of a simple PWM implementation process and can easily be integrated with a predictive algorithm, thereby providing a constant switching frequency (CSF) of operation. The particular single modulating and single carrier‐based PWM technique with floor function is also suitable for low and high switching frequency (LSF‐HSF) operations. The validation of floor function‐based PWM technique in open‐loop and closed‐loop F2‐SCM2PC2 techniques has been effectively verified through experimentation on QB‐SCMLI topology with consideration of resistive–inductive load.

A Three-Phase Nonisolated Pseudo-Six-Phase-Based Integrated Onboard Battery Charger for Electric Vehicles

The trending modern designs of electric vehicle (EV) motors are concerned with maximizing the machine torque density while offering a fault tolerance capability. Among different available stator winding layouts, the so-called pseudo-six-phase (P6P) winding has recently been proposed, which offers an improved torque density and fault tolerance over conventional six-phase distributed winding. An integrated onboard battery charger (IOBC) has also been proposed as a new leading technology that employs the propulsion components of the EV in the charging process to achieve the highest possible charging current with zero machine torque production. In this context, this article proposes a new P6P-based IOBC system. Two different controllers have been investigated, namely, conventional proportional–resonant (PR)-based current control and predictive current control (PCC) techniques. Under the charging mode, the control objectives aim at achieving a balanced three-phase grid current while nullifying machine torque production. To this end, the sequence stator currents are regulated to ensure a balanced <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${xy}$ </tex-math></inline-formula> current, while both the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\alpha \beta }$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${ {0}}^{ {+}}{ {0}}^{ {-}}$ </tex-math></inline-formula> current components are controlled to zero. Furthermore, a novel postfault controller using a PR-based current controller has been proposed, which ensures balanced grid line currents under one open-phase fault. A comparative experimental study has been carried out under different controllers for both vehicle-to-grid (V2G) and grid-to-vehicle (G2V) modes using a 2-hp prototype machine.

Simplified Model Predictive Current Control of Four-Level Nested Neutral Point Clamped Converter

Model predictive control (MPC) is an efficient and growing approach to power converter control. This paper proposes an improved and simplified model predictive current control (MPCC) technique for a four-level nested neutral point clamped (4L-NNPC) converter. Conventional MPCC exhibits better performances as compared to the conventional linear control system such as fast dynamic response, consideration of the system constraints, and nonlinearities. However, the application of the conventional model predictive current control (MPCC) approach on complex systems provokes a significant number of calculations, which is the main hurdle to its practical implementation. To fix this flaw, this paper proposes an effective algorithm to shorten the execution time of the conventional MPCC. In this proposed technique, 216 current predictions of the conventional MPCC are skipped and converted into one required voltage vector (RVV) prediction. With this equivalent reference voltage transformation, the calculation burden of MPCC is significantly reduced, while the output performance is not influenced. The results of the simplified MPCC for the 4L-NNPC converter are analyzed and compared with the conventional MPCC. The computational time is reduced by 19.56% using the simplified MPCC, while keeping an approximately similar error of output currents. The switching frequency and total harmonic distortion (THD) of the proposed method are reduced by 8.16% and 0.07%, respectively, as compared to the conventional technique. These results demonstrate the fact that that the performance of a conventional MPCC is enhanced with the proposed MPCC. The proposed algorithm can be applied to several inverter topologies.

A Novel Single-Phase Shunt Active Power Filter with a Cost Function Based Model Predictive Current Control Technique

For a single-phase Shunt Active Power Filter (SAPF) with a two-step prediction, this research presents a modified current control based on a Model Predictive Current Control (MPCC) technique. An H-bridge inverter, a DC link capacitor, and a filter inductor comprise the single-phase SAPF topology. The SAPF reference current is computed using the DC-link capacitor voltage regulation-based PI control technique. The weighting factor-based model predictive current controller is used to track the current commands. The essential dynamic index for evaluating waveform quality is the Total Harmonic Distortion (THD) of a source current and switching frequency of power switches. The conventional methods the THD and switching frequency are not considered as an objective function, so that a weighting factor-based MPCC technique is used to obtain a good compromise between the THD of the source current and switching frequency of power switches. Through MATLAB simulation and experimentation with the Cyclone-IV EP4CE30F484 FPGA board, the usefulness of the proposed control technique is proven. As compared with hysteresis, predictive PWM, and conventional MPCC control methods, the cost function-based MPCC algorithm provides a lower switching frequency (13.4 kHz) with an optimal source current THD value.

Switching Frequency Formulation for Predictive Current Control in Grid-Connected VSI

In this paper, a switching frequency has been formulated for grid-connected voltage source inverter (VSI) operated using the Continuous Control Set-Predictive Current Control (CCS-PCC) technique. An instantaneous expression of switching frequency has been derived for the VSI operated using the predictive current control technique. The effect of sampling frequency has been analyzed on the switching frequency of the converter operation. The effect of sampling time has a direct impact on the switching frequency as the cost function of the PCC depends on the sampling frequency. The analysis provides a generalized mathematical expression of switching frequency for the VSI operating in current control mode using the predictive current control method. With the help of this generalized expression, the maximum switching frequency and minimum load current error have been obtained. Simulation has been performed for verification of the analytical results through a Typhoon HIL-402 kit for real-time simulation and experimental validation.

Model predictive current control with lower switching frequency for permanent magnet synchronous motor drives

The model predictive current control (MPCC) technique has been an effective alternative for motor drive applications requiring fast dynamic response. However, the conventional MPCC suffers from high switching losses due to high switching frequency of the inverter. This study proposes a low average switching frequency MPCC method based on boundary-constrained quadratically extrapolated current trajectory for a permanent magnet synchronous motor drive. First, a quadratic function-based current prediction model is constructed to obtain the current trajectory in the long-term future. Second, the boundary constraint is designed to obtain the prediction horizon which is changing in real-time in order to ensure the validity of the predicted current trajectory. Finally, the cost function established according to the value of the prediction horizon is used to reduce the average switching frequency. In comparison with the conventional MPCC method, the proposed method can significantly reduce the switching frequency of the inverter. In the meantime, fast dynamic response and high steady-state performance of the conventional MPCC method are preserved. Both simulation and experimental results of the proposed method and the conventional MPCC method are presented to verify the feasibility and advantages of the proposed method.

Recent Advances in Model Predictive and Sliding Mode Current Control Techniques of Multiphase Induction Machines

Multiphase machines have attracted the attention of the research and industrial communities due to their advantages, namely better power distribution and fault-tolerant capabilities without extra hardware. However, the multiphase machine requires high-performance control strategies to take advantage of these features. From this perspective, the field-oriented control with the inner current control loop that uses using an explicit modulation stage has been considered the benchmark solution thanks to the reduced harmonic distortion obtained with this regulation strategy. Nevertheless, nonlinear controllers, thanks to their inherent nature, allow exploiting the extra multiphase capabilities in a simplified manner. Consequently, this paper aims to concentrate and discuss the latest developments on nonlinear current control of two of the most popular multiphase electric drive configurations, five-phase and six-phase. Then, this paper covers mainly finite-control-set model predictive control and their variations. Moreover, sliding-mode control is also explained. Finally, this paper includes experimental assessments of the most recent nonlinear current control techniques considering steady-state and transient conditions, stability and performance analysis.

Experimental Stability Study of Modulated Model Predictive Current Controllers Applied to Six-Phase Induction Motor Drives

Modulated model predictive current control techniques are considered an interesting option to control multiphase drives due to their control flexibility and fast dynamic response. However, a practical stability study of those techniques is still missing. This article presents an experimental stability study, to quantify the limits of stability, to modulated predictive current controllers applied to an asymmetrical six-phase induction machine. Experimental results are presented to verify the theoretical analysis results in terms of stability ranges regarding sampling frequency and rotor speed.

Switching Regulation in the Control of 5-Phase Permanent Magnet Synchronous Motor Fed by 3×5 Direct Matrix Converter

Matrix converter is an AC-AC direct power converter comprising of an array of bi-directional switches. It does not require an intermediate DC-link and allows sinusoidal output waveforms with varying amplitudes and frequencies. The configuration of these bi-directional switches decides the number of inputs and outputs of the matrix converter. This research uses a direct matrix converter (DMC) as a phase-changing device that can convert a three-phase AC voltage into a 5-phase AC voltage. The DMC is modulated with the model predictive control algorithm. The output of DMC is fed to a five-phase permanent magnet synchronous motor (PMSM). The model predictive current control technique for DMC is carried out by developing a mathematical model of an input filter and PM motor used as a load. The predictive control of DMC results in sinusoidal output current, and it also enables the frequency variation in the output current. This frequency variation is useful in controlling the speed of the motor connected to the load. After controlling the 5-phase motor, the switching frequency regulation is done to observe its effect on the motor's stator current waveforms. Switching frequency regulation helps to limit the unnecessary switching of DMC. We developed a MATLAB-based Simulink model to study PMSM, and detailed results are presented. The results show that switching regulation can significantly reduce the switching frequency without compromising the current waveform quality.

Predictive current control of FL-shunt active power filter for dynamic and heterogeneous load compensation

In this paper, a predictive current control technique is utilized to generate switching pulses for four-leg-shunt active power filter (FL-shunt active power filter). The d-q theory technique is executed for removing the reactive and harmonic components of load current. MATLAB-based simulation and FPGA-controlled experimentation have been carried out to evaluate the behavior of predictive current control technique under dynamic and heterogeneous loading conditions. The 3-phase induction machine is considered as a dynamic load, and the capability of FL-shunt active power filter is assessed for compensating the reactive power. The compensation behavior of FL-shunt active power filter is observed with heterogeneous load, which is an amalgamation of dynamic and unstable static loads. Under steady-state and transient conditions, the simulation and experimentation results demonstrate that the proposed technique makes the supply current sinusoidal as well as balanced; compensates the reactive power; maintains near to unity power factor at the point of common coupling (PCC); and annuls the current flow in neutral conductor.

Variable Speed Operation of Brushless Doubly Fed Reluctance Machine Drive Using Model Predictive Current Control Technique

To accomplish an accurate and fast drive control, model predictive control (MPC) is considered as an effective control strategy nowadays. In MPC, the voltage vectors required for inverter control are evaluated considering the control objectives defined in terms of current or power or torque and flux. The optimal one is selected using an iterative prediction loop and applied in the next control interval. This form of MPC is simple in implementation and shows appreciable dynamic performance but the steady-state performance is compromised due to the limited availability of the number of voltage vectors, especially in the case of a two-level voltage source inverter. The present article explores the viability of the MPC approach for a new candidate such as a brushless doubly fed reluctance machine drive considering its secondary current as the control variable. Moreover, to tackle the steady-state inferiority issue, the duty-cycle control concept is inducted. In comparison to field-oriented control (FOC), the proposed scheme offers a straightforward solution for current control by replacing the inner current proportional-integral controllers and pulsewidth modulator with an optimization-based model predictive current controller. An extensive simulation study in MATLAB, vis-à-vis comparison with FOC scheme, and experimental validations justify the claims of the proposed work.

Predictive current control in electrical drives: an illustrated review with case examples using a five‐phase induction motor drive with distributed windings

The industrial application of electric machines in variable-speed drives has recently grown thanks to the development of microprocessors and power converters. Although three-phase machines constitute the most common case, the interest of the research community is also focused on multiphase machines with more than three phases. The principal reason lies in the exploitation of their advantages such as reliability, better current distribution among phases or lower current harmonic in the converter, to name a few. Nevertheless, multiphase drive applications require the development of complex controllers to regulate the torque (or speed) and flux of the machine. In this regard, predictive current controllers have appeared as a viable alternative due to an easy formulation and high flexibility to incorporate different control objectives. It is found, however, that these controllers face some peculiarities and limitations in their use that require attention. This work attempts to tackle the predictive current control technique as a viable alternative for the regulation of multiphase drives, paying special attention to the development of the control technique and the discussion of the benefits and limitations. Case examples with experimental results using a symmetrical five-phase induction machine with distributed windings are included to this end.

Modulated predictive current control for a two‐level grid‐connected converter with over‐modulation capability

Modulated model predictive control (M2PC) approaches have been widely investigated owing to their improved steady-state performance and constant switching frequency operation. However, most of these methods either increase control complexity or cannot obtain optimal solutions under certain operating conditions such as lower modulation index and near the boundary of linear and over-modulation regions. To overcome these limitations, this study proposes a new modulated predictive current control technique based on a novel virtual vector synthesis. The optimal duty cycle is obtained by solving the optimisation problem defined by the cost function. To minimise the tracking error of the input current, a simple non-linearity compensation method for the converter is also demonstrated. The experimental results confirm that the proposed technique significantly reduces the steady-state error of the controlled objective and the ripples in the input current without sacrificing the transient performance compared to other existing M2PC methods.

Evaluation of Predictive Current Control Techniques for PM BLDC Motor in Stationary Plane

In general, PM BLDC motors are injected with square wave phase currents through PI-PWM control in a-b-c reference plane to ensure maximum torque-per-ampere. The operation of PM BLDC motor in a stationary plane has shown considerable simplification in design, and analysis in the control techniques. The present paper considers the injection of square wave phase current through predictive current control strategies in the stationary plane. For the evaluation of performance, cases of deadbeat predictive control, hysteresis based predictive control, and finite control-set model predictive control (FCS-MPC) methods are considered. Control schemes have been designed for 48V, 660W PM BLDC motor. Comparative evaluation is carried out in terms of the harmonic components available in the current and torque, tracking of the current trajectory in the stationary plane in the low and high-speed region, and execution time of all the control methods. Considered predictive methods are tested on an experimental prototype, and control is implemented through digital Signal Processor (DSP) TMS320F28335. Evaluation leads to the conclusion that predictive control performs better than PI-PWM for reducing commutation torque ripple, keeping current harmonics under control. It is observed that predictive control strategies in the stationary plane, improve the torque-speed characteristic to the wider utilization of constant torque zone of operation as compared to conventional strategies.

An Efficient Predictive Current Control Strategy for a Four-Level Open-End Winding Induction Motor Drive

This article proposes a new predictive current control (PCC) strategy for a dual-inverter fed four-level (4-L) open-end winding induction motor drive (OEWIMD). The individual inverters of the dual-inverter system are operated with dc-link voltages, which are in the ratio of 2:1. In general, the PCC for the 4-L OEWIMD requires the evaluation of all of the 37 available voltage vectors (VVs) to select the optimal one. An improvised PCC is proposed in this article, wherein the inverter with lower dc-input voltage is clamped, while the other inverter is switched around it. An important feature of the proposed PCC is that it evaluates only five candidate VVs to determine the optimal vector. The simulation and the experimental results reveal that the performance of the proposed PCC technique is superior to the conventional PCC in terms of voltage and current total harmonic distortion (THD), torque-ripple, and total drive loss. Furthermore, the proposed PCC results in the reduction of the computational burden on the controller. Also, as the reduction of switching frequency is inherent in the proposed PCC strategy, there is no requirement to add an additional constraint to reduce it in the cost function.