Papers by Mini K. Namboothiripad
International journal of computing and digital system/International Journal of Computing and Digital Systems, Mar 15, 2024
This paper explains the strategies to create a hardware-based real time model of DC servomotor by... more This paper explains the strategies to create a hardware-based real time model of DC servomotor by utilizing the FPGA technology that can accurately simulate the behavior of the servomotor in real-time. Such FPGA based hardware model is useful for testing control algorithms, validating designs, and optimizing performance for various applications because of its reconfiguration capabilities. The uniqueness of our paper lies in the application of C language for modeling a DC servomotor by discretizing the model with both Backward Euler (BE) and Trapezoidal (TRZ) methods. The discretized models are then implemented on FPGA using Vivado HLS and the performance is analyzed with change in step-size by comparing with the transfer function (TF) model. With 100 µsec step-size, TRZ response is found to be matching with the TF model, however, a step-size of 0.6 µsec was required for the BE. Also analyzed the feasibility of Hardware-in-the-Loop (HIL) technique by connecting the DC servomotor in loop with the PID controller on FPGA, again by varying the step-size. Both the BE and TRZ models could track the reference speed within 2 msec, because of the PID controller, however faster dynamics was observed in case of TRZ as compared to BE, especially with larger step-size. This analysis demonstrates the impact of step-size and discretization technique on real-time modeling. By selecting suitable values, the FPGA model can be efficiently harnessed to develop a tailored control algorithm and optimize performance for diverse applications.
DC-DC converters are required to be designed to provide a well stabilized output voltage for a wi... more DC-DC converters are required to be designed to provide a well stabilized output voltage for a wide range of input voltage and load current variations. This paper presents the output voltage control of buck converter under continuous conduction mode using sliding mode controller. State space model of the buck converter is developed with output voltage error as one of the state variables. A suitable sliding surface is designed to force the trajectory to track the sliding line and to reach the asymptotically stable origin. The voltage error is given as the input to the sliding mode controller. Output of the controller controls the gate of the power electronic switch and thus maintains the output voltage at desired value. Simulation results show that the output voltage remained constant for wide variations of load and input voltage conditions.
2016 10th International Conference on Intelligent Systems and Control (ISCO), 2016
Use of power electronic devices creates the power quality issues by generating harmonics and reac... more Use of power electronic devices creates the power quality issues by generating harmonics and reactive power in the utility system. Active power filter is one of the best solution to reduce the harmonics level in the system. In this paper single phase shunt active filter using sliding mode control is implemented in MATLAB/Simulink. Sliding mode controller acts as a current controller to control filter inductor current by providing harmonics and reactive current required by the load. The switching signals to the shunt active power filter is generated based on the sliding surface and the source voltage. PI controller is used to control DC link voltage of active power filter along with generation of reference source current. Performance of proposed shunt active filter is analyzed under nonlinear and combined non-linear and linear load. It is observed that shunt active power filter improves the total harmonic distortion (THD) and power factor under variable load condition.
2014 6th IEEE Power India International Conference (PIICON), 2014
DC-DC converters are widely used in the switched mode power supplies for its high conversion effi... more DC-DC converters are widely used in the switched mode power supplies for its high conversion efficiency and flexible output voltage. Regulation problems of the DC-DC converters under variable load and parametric condition lead to the development of sliding mode controller. In this paper adaptive and non-adaptive sliding mode controllers are implemented to control the output voltage of buck converter under variable load conditions. A suitable sliding coefficient is designed by deriving the state space representation of the buck converter and modified it to be adaptive to the loading conditions. It is observed that with the adaptive sliding mode controller, the output voltage not only remained constant for step overload but also reached the desired value faster. Adaptive sliding mode controller also saved the buck converter from entering into discontinuous mode under step under load condition.
Abstract: Reactive power compensation in a power distribution network plays a vital role in impro... more Abstract: Reactive power compensation in a power distribution network plays a vital role in improving voltage and power system stability. Flexible AC transmission system (FACTS) devices like Static Var Compensators (SVCs) are used to control reactive power generation or absorption in long transmission line. However, these SVCs will introduce harmonic current in to the system due to the operation of thyristor controlled reactors (TCR). This paper proposes a modified genetic algorithm approach to minimize the harmonics injected into the systems with the operation of TCR-FC type SVC used in conjunction with fast-changing loads. Optimum triggering delay angles used to trigger thyristors in TCR are calculated using the proposed genetic algorithm to achieve better, smooth and adaptive control of reactive power as well as harmonics. This approach can be effectively used to limit the THD as well as receiving end voltage within the acceptable range for linear as well as nonlinear load condit...
The position control study of DC servo motors is very important since they are extensively deploy... more The position control study of DC servo motors is very important since they are extensively deployed in various servomechanisms. Normally PID controllers are used to improve the transient response of DC servo motors. At present, most tuning methods are designed to provide workable initial values, which are then further manually optimized for a specific requirement. This paper presents a flexible and fast tuning method based on genetic algorithm (GA) to determine the optimal parameters of the PID controller for the desired system specifications. Simulation results show that a wide range of requirements are satisfied with the proposed tuning method. Keywords— DC servomotor, Genetic Algorithm, Optimization, PID controller, PID Tuning, Transient response.
2020 33rd International Conference on VLSI Design and 2020 19th International Conference on Embedded Systems (VLSID), 2020
It is well known that solving a sparse system of linear equations is the workhorse critical step ... more It is well known that solving a sparse system of linear equations is the workhorse critical step in analog and RF circuit simulation. The LU factorization of sparse system matrix is a key operation in order to solve a system of linear equations. Extracting parallelism to factorize a sparse matrix requires knowledge of pattern of non-zeros in the matrix. Exploiting the fact that sparsity patterns of matrices involved in circuit simulations do not change across iterations, the schedule of computing steps of LU factorization can be statically determined and analyzed for parallelism. This approach has been well investigated by [1] and [2] in recent years. Our work improvises this well-researched approach and exposes more parallelism, thereby yielding improved results (by factor up to 2). The accelerated design is prototyped using custom high-level-synthesis tool specific to LU decomposition problem.The case of RF Circuits is treated slightly differently. Such circuits have a number of n...
The development of an accurate Real-Time emulation system for Modular-Multilevel-Converter (MMC) ... more The development of an accurate Real-Time emulation system for Modular-Multilevel-Converter (MMC) is a challenging task due to the presence of a large number of sub-modules (SMs). This paper explains the strategies to implement the MMC model in real-time, with up to 1600 SMs in each arm, by exploiting the available arm-level and SM-level parallelism using FPGA. Computations are made more parallel by decomposing the converter equivalent model into two multiports for further analysis. Our 200 MHz custom model with 1600 SMs/arm on the ZCU104 board yields a speedup of up to 6.03 as compared to the 1.2 GHz on-chip A53 ARM processor. Also with our 400 SMs/arm, the latency could be reduced to 7.27µs as compared to the 9µs reported in the literature. Accuracy is verified by comparing with the MATLAB-Simulink model and observed that the percentage error in the load current is less than 1%.
DC-DC Converters are usedin effective conversion of the unregulated input voltages to regulated o... more DC-DC Converters are usedin effective conversion of the unregulated input voltages to regulated output voltages. Sliding mode control technique is one of the methods used to achieve smooth and robust voltage control. The first order sliding mode control method regulates the output voltage to the desired value but suffers from the phenomena called chattering. Chattering reduces the life of the converter switch. Various methods such as boundary layer control, higher order sliding mode control etc. can be used to reduce this chattering effect. Boundary layer control uses continuous approximation of the discontinuous control signal to reduce chattering. However it reduces the speed of response and introduces steady state error. Chattering can be effectively reduced by using higher order sliding mode control. In this paper, Second order Sliding mode controller is implemented by using the Super-Twisting Algorithm. Results for the second order control are compared with the first order cont...
IEEE Transactions on Industry Applications
Strategies to implement emulation of large power electronic converters with different topologies ... more Strategies to implement emulation of large power electronic converters with different topologies using a generic multiport decomposition technique with different levels by exploiting the parallel nature of field programmable gate array (FPGA) are explained in this article. Switches are modeled as on/off resistors and a Python-based software tool is developed to precompute the system matrices corresponding to each switch combination. Converters like three-phase five-level-flying-capacitor are modeled in C using the precomputed data, converted to VHDL and implemented on ZCU104 and ZedBoard using Vivado and verified against the corresponding MATLAB-Simulink model. Also, the real-time performance is analyzed by connecting it for the closed-loop speed control of induction motors of various specifications by changing the load torque and reference speed and found out that the latency is less than 6 $\\mu$s, which is sufficient for the wide range of variable frequency drive applications.
2017 International Conference on Nascent Technologies in Engineering (ICNTE)
Harmonics in the power system can be reduced and thus power quality can be improved with the use ... more Harmonics in the power system can be reduced and thus power quality can be improved with the use of Active power filter. In this literature, fixed switching frequency single phase shunt active filter based on sliding mode controller is modeled and analyzed using MATLAB. Control law is designed to generate both continuous and discontinuous component of the control signal. Pulse width modulated switching signals to the shunt active power filter are generated from the Control output of the sliding mode controller. DC link capacitor voltage is controlled using PI controller which gives the reference source current. Performance of single phase shunt active power filter with nonlinear and combined nonlinear and linear load is demonstrated with the help of simulation results.
2019 National Power Electronics Conference (NPEC), 2019
Development of accurate Real-Time systems with power electronic converters is a challenging task ... more Development of accurate Real-Time systems with power electronic converters is a challenging task due to its high switching frequency and the time varying circuit topology. This paper explains the strategies to implement power electronic circuit models in real time, by exploiting the parallel and distributed computing nature of FPGA, with three-phase-three-level diode-clamped inverter as a case study. A generic multiport decomposition technique is applied to improve parallelism and to reduce the size of the matrix for the computation. Also, by developing a PySpice based utility, which pre-computes all the system matrices from the given netlist, implementation is made more adaptable to different partitions and circuit variations. Target circuit is implemented in C/C++ language, converted to VHDL and implemented on ZedBoard (XC7Z020) using Xilinx Vivado tools. With this generalized approach, a latency of less than $5\mu\mathrm{s}$ is achieved with reasonable utilization of resources, o...
Uploads
Papers by Mini K. Namboothiripad