Processor In Loop Research Articles

Designing robust hybrid controllers for enhancing output voltage regulation in CPL feed boost converters through backstepping and nonsingular fast terminal sliding mode approaches

This paper presents a novel and robust hybrid controller that combines the backstepping controller with the nonsingular fast terminal sliding mode controller (NFTSMC) for DC-DC boost converters (DDBCs) operating alongside constant power loads (CPLs). The primary aim of the controller is to enhance the stability of the DC-bus voltage while consistently delivering power to the CPL. To achieve this objective, the exact feedback linearization approach is applied to transform the nonlinear dynamical model of the DDBC into Brunovsky’s canonical forms. The incorporation of matched uncertainties into the dynamical model illustrates the robustness of the proposed control approach. The hybrid controller is formulated based on this model, leveraging Lyapunov stability theory to ensure large signal stability under the designated control law. Significantly, the NFTSMC effectively addresses the singularity problem associated with sliding mode controllers (SMCs). The effectiveness and resilience of the proposed controller are validated under variations in input voltage, reference voltage, and power demand. Comparative analysis is conducted by contrasting simulation results with those obtained using conventional SMC (CSMC) and a typical PI controller (PIC). The results unequivocally highlight the superiority of the proposed controller in terms of ensuring system stability and providing a rapid response across various operating modes. Furthermore, to authenticate the practical applicability of the proposed controller, processor-in-loop (PIL) validation is employed, confirming its effectiveness in real-world scenarios.

Closed loop operation and testing with processor-in-loop (PIL) simulation of an asymmetrical six-phase open-ended winding synchronous machine

This paper presents a simple closed loop indirect field-oriented controlled operation for an asymmetrical six-phase open-ended winding synchronous motor in a newly defined two-axis (M-T) coordinate system, in which the common mutual leakage coupling between the two stator winding sets has been considered. Phasor diagram of the vector-controlled motor is developed under steady-state. Performance of a six-phase synchronous machine is presented in all four quadrant operations. A complete mathematical model is developed and controlled in a closed loop on Matlab/Simulink environment. Suitability and practical validity of the proposed control scheme are shown by conducting a test using processor-in-loop (PIL) by employing the STM32F407G board. An efficient data transfer at a high baud rate was obtained between the target board and host through an externally connected serial communication interface by using a USB-USART converter i.e. FT32RL board.

Frequency Fluctuation Mitigation in a Single-Area Power System Using LQR-Based Proportional Damping Compensator

To maintain the stability of the power system, frequency fluctuations must be reduced in the shortest possible timeframe. Load frequency control (LFC) plays a critical role in achieving this objective by regulating the system frequency and the desired demand or output power in an interconnected network, thereby enabling the system to adapt the load disturbances. In order to effectively mitigate the frequency fluctuation caused by load variation in a single-area power system, a new control strategy integrating a linear quadratic regulator (LQR), a proportional controller, and a damping compensator is proposed in this paper. The proposed controller is named as the LQR-based proportional damping compensator which mitigates the frequency fluctuation of a single-area power system. MATLAB/Simulink simulation is conducted on a single-area power system to demonstrate the efficacy of the proposed control technique. The simulation results demonstrate that the proposed method successfully reduces frequency variations, maintains system frequency within reasonable limits, and substantially reduces the settling time as compared to other existing control techniques. Apart from the simulation analysis, to experimentally validate the performance of the proposed controller, a hybrid multiprocessor-based processor-in-loop (PIL) technique is also introduced in the paper. Both the simulation and experimental results prove the promising performance of the proposed controller for mitigating the frequency fluctuation of a single-area power system.

Real-Time Power Quality Enhancement in a Hybrid Micro-Grid Using Nonlinear Autoregressive Neural Network

The extensive use of renewable energy sources (RESs) in energy sectors plays a vital role in meeting the present energy demand. The widespread utilization of allocated resources leads to multiple usages of converters for synchronization with the power grid, introducing poor power quality. The integration of distributed energy resources produces uncertainties which are reflected in the distribution system. The major power quality problems such as voltage sag/swell, voltage unbalancing, poor power factor, harmonics distortion (THD), and power transients appear during the transition of micro-grids (MGs). In this research, a single micro-grid is designed with PVs, wind generators, and fuel cells as distributed energy resources (DERs). A nonlinear auto regressive exogenous input neural network (NARX-NN) controller has been investigated in this micro-grid in order to maintain the above power quality issues within the specific standard range (IEEE/IEC standards). The performance of the NARX-NN controller is compared with PID and fuzzy-PID controllers. The single micro-grid is extended to design a three-phase large-scale realistic micro-grid structure to test the feasibility of the proposed controller. The realistic micro-grid is verified through addition of line-impedance, communication delay, demand response, and off-nominal situations. The proposed controller is also validated by simulating different test scenarios using MATLAB/Simulink and TMS320-based processor-in-loop (PIL) for real-time implementation.

Single current sensor based fault tolerant control of interior permanent magnet synchronous machine for drive applications

This paper presents an integrated method for current sensor fault detection and fault tolerant control (FTC) for traction interior permanent magnet synchronous motor (IPMSM). The proposed current sensor fault detection method is based on detecting changes in the d-q axis current. The FTC is based on d-q axis current estimation from the reference d-q axis current and the phase current measured by the surviving current sensor. The current estimation process is independent of machine parameters. Hence the estimation is robust and requires less computational cost. The effectiveness of the FTC method is verified by the transient analysis. Such FTC is suitable for electric vehicle traction applications to ensure non-stop control operation of the drive in the entire range of speed. The efficacy of the proposed FTC method is tested through extensive simulations in MATLAB/Simulink environment. The real-time applicability of the proposed FTC method using the cost-effective digital signal processor (DSP) is verified on Texas Instruments© TMSF28379D through the processor in loop (PIL) simulation model.

An integral backstepping controller design for compensated distribution networks with rapid earth fault current limiters in bushfire prone areas

AbstractThis paper presents a nonlinear integral backstepping controller (I‐BSC) design scheme for a T‐type residual current compensation (RCC) inverter used in compensated distribution networks with rapid earth fault current limiters (REFCLs). The major control task for the proposed scheme is to reduce the fault current to a value suitable for the mitigation of powerline bushfires due to single phase‐to‐ground faults in compensated distribution networks. The key distinct feature of the proposed I‐BSC over the traditional backstepping controller (T‐BSC) is that it introduces an integral action for analyzing the dynamic of the tracking error which minimizes its steady‐state value and ensures better dynamic performance. In order to prove the global asymptotic stability of the RCC inverter with the proposed integral backstepping controller (I‐BSC), the Lyapunov function‐based theory is used. Finally, the performance of the I‐BSC is analyzed on the MATLAB/Simulink environment and compared with a T‐BSC. The performance of both I‐ and T‐BSCs is assessed in terms of transient behaviors of the injected current to the neutral, fault current, and line‐to‐ground voltage of the faulty phase to ensure the standard operational criteria for self‐extinguishing powerline bushfires. Simulation results clearly demonstrate that both controllers fulfill operational standards for REFCL‐compensated networks though the I‐BSC archives better transient behaviors while comparing with the T‐BSC. Results from the processor‐in‐loop (PIL) validations are also included to further justify the applicability of the newly proposed scheme in the real‐time environment.

A new method for controlling an induction motor using a hybrid discretization model predictive field orientated control.

The dynamic performance of the Model Predictive Control (MPC) of an Induction Motor (IM) relies on the accuracy and computational efficiency of the Discretisation Technique (DT). If the discretisation process is inaccurate or slow approximation, the MPC will exhibit high torque ripple and lower load handling capabilities. Traditionally, Euler’s method is used to discretise the MPC, which merely relies on the predictor to yield a fast, but less accurate system approximation. In contrast, Heun’s method uses a combination of predictor and corrector at alternate sampling intervals to improve the discretisation accuracy; however, the controller response becomes slow due to increased computational intensity of the algorithm. In this study, a new Hybrid Discretisation Technique (HDT) for Model Predictive Field Oriented Control (MPFOC) for IM control systems is presented to achieve robust discretisation with improved accuracy. In the proposed approach, Euler’s method is used to discretise the system at the first nine samples, followed by the predictor-corrector at the tenth sampling interval, accomplishing the desired speed and accuracy of discretisation. This newly proposed HDT in MPFOC is verified with Processor-In-Loop (PIL) for a three-phase IM with bi-directional rotation under varying load conditions. The results indicate that the IM torque ripple is reduced by up to 20%, whereas, the load handling capability is increased by up to 10%. Moreover, the controller gives 20% and 23% improvement in rise time and settling time, respectively, under high loading conditions, as compared to traditional Euler and Heun methods.

Analytical Expression for Line Voltage THD of Three-Phase Staircase Modulated Multilevel Inverters

In this article, a simple closed-form analytical expression for the line-voltage total harmonic distortion (LTHD) of three-phase staircase-modulated (SCM) multilevel inverters (MLI) is proposed. The revealed expression is valid for any conventional MLI topology with arbitrary number and parity of voltage levels. The proposed formulation is presented as an analytic function of the number of voltage levels (N) and the phase switching angles (PSA); thus, it is suited to MLIs of equal voltage source supply and of any topology. This function may be employed for accurate LTHD calculation and optimization. The results are verified against LTHD calculations and optimizations, obtained numerically from previous works. Both processor in loop (PIL)- and controller + hardware in loop (C-HIL)-based real-time experimental validations are included as well. A downloadable file containing the Maple and MATLAB functions of the proposed expression are also provided.

Higher‐order sliding mode current controller for grid‐connected distributed energy resources with LCL$\mathrm{LCL}$ filters under unknown grid voltage conditions

The control of the current injected into the grid with lower harmonics is considered as one of the most important issues for the grid integration of distributed energy resources (DERs). The unbalances and harmonics in the grid voltage usually pollute the current injected into the grid due to the power electronic interfaces, for example, inverters. To address such problems, the present paper proposes a nonlinear higher order sliding mode controller (HOSMC) for grid-connected three-phase inverters with LCL $\mathrm{LCL}$ filters in order to control the current injected into grid and improve the power quality. The proposed current controller injects the desired current into the grid with lower values of total harmonic distortions (THDs) under any grid voltage condition as well as it reduces the harmonics in the grid voltage. Apart from these, the proposed scheme is developed to provide robustness against parametric uncertainties where these uncertainties are modeled using the Taylor series expansion method. Finally, the performance of the system is evaluated using processor-in-loop (PIL) simulations via MATLAB/Simulink platform through the implementation on a system considering the capacity of the DER as 2 kVA per phase and compared with other existing control strategies.

Design of a Nonlinear Integral Terminal Sliding Mode Controller for a PEM Fuel Cell Based on a DC-DC Boost Converter

This paper proposes a robust nonlinear controller for a proton exchange membrane fuel cell coupled with a DC-DC boost converter. The key feature is to maintain the desired reference output voltage despite significant disturbances while improving transient stability. In order to do this, a nonlinear robust integral terminal sliding mode controller (ITSMC) is proposed, along with the derivation of the control law, explanation of the reachability analysis, and stability condition. An adapted integral sliding surface is used to capture the dynamics caused by variations in the input voltage and loads. In addition, a modified reaching law is proposed to guarantee the finite time convergence while reducing the chattering. Afterward, the Lyapunov control theory is employed to evaluate the DC-DC boost converter’s large-signal stability while guaranteeing the resilience of the proposed controller. Finally, the applicability of the proposed controller is evaluated through comprehensive analyses on both the simulation platform and the real-time processor-in-loop (PIL) platform under various operating conditions, such as the variation in load resistance, reference output voltage, etc. All of the results, when compared to an existing integral terminal sliding mode controller, indicate quick reference tracking capability with reduced overshoots and robustness against disturbances.

A finite time adaptive back‐stepping sliding mode control for instantaneous active‐reactive power dynamics based DFIG‐wind generation towards improved grid stability

AbstractIn this paper, a low computational, robust nonlinear feedback control is proposed as independent distributed generation controller (IDGC) for doubly fed induction generator (DFIG) based wind power generation system (WPGS). WPGS integration as distributed generation (DG) to grid point of common coupling (PCC) is reflecting high power loss profile in terms of low frequency oscillations under grid operational contingencies and have high instability hazard under unbounded uncertainties like unintentional islanding operation. Thus, to improve the stability margin of DFIG‐WPGS integration fast DG dynamic relations are obtained, where instantaneous active‐reactive power (P‐Q) formulation is proposed to avoid unnecessary phase locked loop (PLL) angle (ω) estimation. The feedback path is designed with proposed finite time adaptive backstepping sliding mode control (FTABSMC) for IDGC operation according to ISA‐95 standards. The FTABSMC is ensured with bounded/unbounded uncertainty handling capability by incorporating backstepping based dynamic error profile depletion and with enhanced stability margin by finite time sliding surface based error trajectory to equilibrium. Further, the adaptive sliding surface estimation is proposed in terms of dynamic uncertainty (energy fluctuation) for robust unbounded uncertainty handling. The stability improvement is established with small‐signal (SS) based closed loop analysis of considered DFIG‐WPGS. The uncertainty handling capability is presented thought rigorous case studies in MATLAB based simulation environment and TMS 320 digital signal processor (DSP) based processor‐in‐loop (PIL) validation.

Unified Predictive Current Control of PMSMs with Parameter Uncertainty

Predictive current control (PCC) applied on permanent magnet synchronous motors (PMSMs) has been developed into mainly three methods: the conventional finite-control-set PCC, the double voltage vectors PCC, and deadbeat PCC. However, each approach has its particular calculation way for voltage vectors selection and respective execution duration. This paper, based on the deadbeat idea, presents a unified predictive current control scheme of PMSMs. Under this scheme, the prior three classes are able to be clearly unified into one frame with lower calculation effort. Furthermore, to cope with problem of parameter mismatch in dq-axis current predictive model, a integrated identification method is proposed. Firstly, data selectors are designed to reject abnormal data of sampling signals, and then the interval-varying multi-innovation least squares algorithm is combined with forgetting factor (V-FF-MILS) to approximate the error terms caused by electromagnetic parameters error. The estimated results are online fed to the model of PMSM to enhance its accuracy. Finally, the processor in loop (PIL) simulation results verify that the proposed integrated scheme has advantages in current control of PMSMs with large-scale parameter uncertainty.

Control and Simulation of Torque Converter Lock-up Clutch

Considering the requirements of dynamic performance and quality during the torque converter locking process, a two parameters latch-up control strategy was designed, and a simulation method to study the control performance by use of processor in loop (PIL) simulation technology was proposed. Through the study of the practically applied requirements of a loader, a two parameter lock-up control strategy with turbine speed signal and gear signal as main control parameters was developed. According to the control strategy, the logic diagram of real-time locking and unlocking control of the latch-up clutch was established by using Matlab/Simulink. Then, PIL technology was used to realize the co-simulation of CCS and Simulink. Simulation results show that the latch-up control model is correct and the lock-up clutch can effectively lock and unlock in accordance with the lock-uprule.

Steering control for underwater gliders

Steering control for an autonomous underwater glider (AUG) is very challenging due to its changing dynamic characteristics such as payload and shape. A good choice to solve this problem is online system identification via in-field trials to capture current dynamic characteristics for control law reconfiguration. Hence, an online polynomial estimator is designed to update the yaw dynamic model of the AUG, and an adaptive model predictive control (MPC) controller is used to calculate the optimal control command based on updated estimated parameters. The MPC controller uses a quadratic program (QP) to compute the optimal control command based on a user-defined cost function. The cost function has two terms, focusing on output reference tracking and move suppression of input, respectively. Move-suppression performance can, at some level, represent energy-saving performance of the MPC controller. Users can balance these two competitive control performances by tuning weights. We have compared the control performance using the second-order polynomial model to that using the fifth-order polynomial model, and found that the former cannot capture the main characteristics of yaw dynamics and may result in vibration during the flight. Both processor-in-loop (PIL) simulations and in-lake tests are presented to validate our steering control performance.

Validation of Lunar Landing GMPSP Guidance from PIL Studies∗∗This work was carried out in DST-FIST supported Advanced Flight Simulation Lab in Indian Institute of Science, Bangalore.

This paper validates the on-board applicability of lunar landing Generalized Model Predictive Static Programming (GMPSP) guidance algorithm using processor-in-loop (PIL) simulations. PIL simulations have been extensively used to verify the real time applicability of algorithms by obtaining run-time information and memory consumption. In this paper, two segmented approach is proposed for the powered descent phase of lunar landing to minimize fuel consumption. The GMPSP guidance algorithm is used for both segments of the powered descent phase to generate the admissible guidance law. The on-board applicability and computational efficiency of GMPSP guidance algorithm are demonstrated through PIL simulation results. In PIL simulations, the GMPSP algorithm is coded in C and validated by using the target TMS320C6748 Digital Signal Processor. The results obtained from the target processor gives an insight into the behavior of the algorithm during the actual mission. The convergence time of the GMPSP algorithm is determined from CPU cycles required by the processor for convergence of the algorithm.

Design and Implementation of Fuzzy Approximation PI Controller for Automatic Cruise Control System

Fuzzy logic systems have been widely used for controlling nonlinear and complex dynamic systems by programming heuristic knowledge. But these systems are computationally complex and resource intensive. This paper presents a technique of development and porting of a fuzzy logic approximation PID controller (FLAC) in an automatic cruise control (ACC) system. ACC is a highly nonlinear process and its control is trivial due to the large change in parameters. Therefore, a suitable controller based on heuristic knowledge will be easy to develop and provide an effective solution. But the major problem with employing fuzzy logic controller (FLC) is its complexity. Moreover, the designing of Rulebase requires efficient heuristic knowledge about the system which is rarely found. Therefore, in this paper, a novel rule extraction process is used to derive a FLAC. This controller is then ported on a C6748 DSP hardware with timing and memory optimization. Later, it is seamlessly connected to a network to support remote reconfigurability. A performance analysis is drawn based on processor-in loop test with Simulink model of a cruise control system for vehicle.

Research on Deadbeat Control for Three-Phase Grid-Connected Inverter in Model Based Design

Using model based design(MBD) method, deadbeat control algorithm for three-phase grid-connected inverter was designed in optimization and realized in hardware. According to the advanced idea of MBD and its basic procedure, the software-in-loop(SIL) test, processor-in-loop(PIL) test and hardware-in-loop(HIL) test for deadbeat control algorithm were mainly researched under MATLAB/Simulink environment choosing TMS320F2812 as object hardware board. In such method, embedded codes could be produced automatically and the errors brought in through algorithm model could be tested and corrected earlier. Meanwhile, simply changing the PIL related modules, the self-defined deadbeat algorithm module could be flexibly applied in other hardware platforms. At last, the correctness and efficiency of deadbeat control algorithm were verified in three-phase grid-connected inverter experiment platform.