Venkata Ramana Kasi

Bio: Venkata Ramana Kasi is an academic researcher from Indian Institute of Technology Guwahati. The author has contributed to research in topics: Relay & PID controller. The author has an hindex of 2, co-authored 7 publications receiving 22 citations.

Design of a new nonlinear predictive PI controller for cascaded control system applications

Abstract: An alternative to traditional feedback control for two subsystems interacting sequentially, cascade control can boost a control system's performance, especially in the face of disturbances. However, the cascade control technique may not provide an adequate performance to track a set point if the outer loop's time delay is significant. A new predictive proportional-integral (PPI) controller is proposed in this paper to counteract and anticipate the time delay of the outer primary process. By combining the best cascade control and predictive control capabilities, the closed-loop performance can significantly be enhanced by superior disturbance rejection. To achieve higher performance than is possible with linear control, in which the gain of the master-slave controller is fixed regardless of the error signal's magnitude, we investigate the use of nonlinear predictive cascade control. Two examples are provided to show how the suggested controller can be applied and how its structure is an improvement over the status quo in terms of controlling delayed systems. Measurement noise is less of an issue with the new structure compared to the old cascade control scheme. The performance, robustness and effectiveness of the suggested controller for set-point tracking under the influence of a load disturbance have been validated in this research.

Transfer function identification of a liquid flow-line pressure control system from simple relay auto-tuning

Abstract: Accurate modeling of liquid flow systems is necessary for the effective operation of the plant under different conditions. The plant dynamics may change with time, and due to this, the operation ma...

Experimental Verification of Robust PID Controller Under Feedforward Framework for a Nonminimum Phase DC–DC Boost Converter

Abstract: This article addresses the disturbance rejection problem of a nonminimum phase dc–dc boost converter operating in the continuous conduction mode (CCM) using a novel robust proportional–integral–derivative (PID) controller design method. The proposed idea is to design the controller using the equivalent feedforward formulation of the modified direct synthesis (MDS) approach. The advantages of the proposed MDS design are: 1) systematic incorporation of disturbance dynamics and the converter dynamics explicitly in the controller design to reduce the complex tuning effort of the controller parameters; 2) allowing the converter to operate close to the performance limit set by the zero in the right half-plane (RHP); 3) the closed-loop performance specifications can be incorporated into the desired loop response using only single tuning parameter based on Bode’s gain crossover frequency inequality; 4) attenuates the loop gain to improve the disturbance rejection; and 5) realization of controller requires only output voltage as a feedback signal. The strength of the proposed MDS method is compared with the internal model control (IMC) method in both simulations and experiments. Based on these responses, the proposed PID ensures robust performance to the model-plant mismatch and allows the output voltage to quickly recover back to the operating voltage in the presence of external disturbances with less inductor current.

Energy-Shaping Speed Controller With Time-Varying Damping Injection for Permanent-Magnet Synchronous Motors

Abstract: This brief presents a novel energy-shaping technique-based speed controller for permanent-magnet synchronous motors (PMSMs) considering machine nonlinearities and load and parameter changes. There are three features: The time-varying damping term is injected into the speed loop, which is automatically updated by the proposed self-tuner. The disturbance observers are designed for both the speed and current loops to achieve better disturbance rejection performance with removal of offset errors without the use of tracking error integral actions. Furthermore, the closed-loop analysis result is provided to demonstrate its beneficial closed-loop properties. The practical advantages are experimentally verified in several convincing scenarios with a prototype 500-W PMSM driven by a three-phase inverter.

Proportional-Derivative Voltage Control With Active Damping for DC/DC Boost Converters via Current Sensorless Approach

Abstract: This brief presents an advanced proportional-derivative (PD) voltage control mechanism for DC/DC boost converters suffering from the parameter and load variations. The proposed controller eliminates the requirement for current feedback by designing the first-order observer estimating the voltage derivative without the use of converter parameters, which corresponds to the first contribution. As another contribution, a specific feedback gain structure for PD-loop and the active damping component guarantees the first-order closed-loop transfer function from the reference to the output voltage by the stable pole-zero cancellation. A prototype bi-directional 3-kW boost converter experimentally validates the closed-loop performance of the proposed technique.

A Robust Decentralized PID Controller Based on Complementary Sensitivity Function for a Multivariable System

Abstract: This brief presents design, development and real-time implementation of a robust decentralized PID controller based on complementary sensitivity function through a graphical tuning method for a multivariable system. ${H_{\infty }}$ criterion is adopted to find out the controller parameters of the proposed robust decentralized PI controller. To verify efficacy of the proposed controller, its performance is compared with that of other decentralized PI controllers. The proposed controller is implemented in real-time on a coupled tank liquid level system. From the simulation and experimental results obtained, it is observed that the proposed controller exhibits superior control performance over other decentralized PI controllers.

Regional-scale allocation of fast charging stations: travel times and distribution system reinforcements

Abstract: Electric vehicle (EV) fleet is constantly increasing over the years and higher adoption is expected in the coming decades A key aspect to support and boost the EV uptake is the adequate availability (number, locations and sizes) of fast charging stations (FCSs) to enable inter-and intra-city travels Since these studies require modelling large regions with uncertainties, a methodology able to provide the least-cost solution is needed This study proposes a scalable methodology that integrates high-resolution traffic flow and multi-phase electrical simulations to find the number, locations and sizes of FCSs at the least societal cost considering the uncertainties in driving patterns It determines potential FCSs locations based on traffic flow and progressively explores these FCSs quantifying capital (equipment and land) and indirect (loss of productivity and reinforcements) costs to identify the least-cost solution Results from a Brazilian case study comprising of a metropolitan region with six cities and 26 primary substations show that, with high adoption of EVs, the investments in equipment represent the most significant components of societal cost Moreover, for metropolitan regions, the societal least-cost solution is found with more but smaller FCSs Finally, is found that neglecting the loss of productivity can significantly affect the results