Browsing by Author "Urundady, V."

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Design of coupled inductors using split winding scheme for bridgeless SEPIC
(Institution of Engineering and Technology jbristow@theiet.org, 2020) Prabhu, P.; Urundady, V.
A bridgeless single-ended primary inductance converter (SEPIC) is a highly preferred single-stage front-end AC-DC converter for applications requiring a wide variation of DC voltage because it also gives improved performance in terms of the quality of supply current. This study presents the design of coupled inductors for the bridgeless SEPIC using the split winding scheme. With coupling incorporated the required value of self-inductances of the input and output inductors for the same performance is reduced. Also, they can be wound on the same core, thereby resulting in a reduction in size. The conventional method of tuning the coupling coefficient by adjusting the air-gap is tedious. A split winding scheme for the distribution of windings over three limbs of E-core for obtaining the desired coupling coefficient is presented. The split winding scheme for the design of coupled inductors for bridgeless SEPIC converter rated for 500 W, 20 kHz is illustrated. The effect of coupling on the volume, weight, cost, and efficiency of the converter is compared with the conventional SEPIC converter without coupling for a similar performance. The performance of the proposed converter is evaluated using MATLAB/Simulink simulation and experimental results with a laboratory prototype rated for 500 W. © The Institution of Engineering and Technology 2020.
Hardware Co-simulation of Pulse Amplitude Modulation Controlled BLDC Motor
(Institute of Electrical and Electronics Engineers Inc., 2022) Prabhu, P.; Kulkarni, S.V.; Urundady, V.
This paper describes the validation of a Field Programmable Gate Array (FPGA)-based controller for Brushless Direct Current (BLDC) motor drive using the hardware co-simulation feature enabled in the Xilinx System Generator (XSG) design tool. To control the speed of the BLDC motor, the proposed BLDC drive uses PAM control of the Voltage Source Inverter (VSI). The PAM control reduces switching losses by allowing the VSI to operate at the frequency determined by synchronous speed. At the front end, a bridgeless SEPIC provides a wide range of DC voltage to the VSI input. When compared to the topology with two separate inductors, the Bridgeless SEPIC coupled inductors reduce the overall component count and the self-inductance required. The converter is designed to operate in Discontinuous Conduction Mode (DCM) by applying a simple voltage follower approach to a SEPIC converter to achieve inherent input current shaping over a wide speed range. The precise reference voltage for the DC link is calculated in the outer speed control loop. The proposed BLDC motor drive is modeled using the XSG design tool, and the controller is implemented in FPGA. Hardware co-simulation is used to evaluate the controller's performance under dynamic conditions such as step changes in reference speed and supply voltage. Â© 2022 IEEE.
One-Cycle Controlled Bridgeless SEPIC with Coupled Inductors for PAM Control-Based BLDC Drive
(2019) Prabhu, P.; Urundady, V.
This paper presents a novel approach for the speed control of BLDC motor for residential air conditioning application, using pulse amplitude modulation (PAM) control of voltage source inverter (VSI). PAM control of VSI is accomplished by using a bridgeless SEPIC converter embedded with coupled inductors at the front end and adopting one-cycle control (OCC) technique in the inner voltage control loop. The DC reference voltage required for inner voltage control loop is obtained using a PI controller in the outer speed control loop and speed feedback signal. The PAM control (DC supply voltage control) of VSI reduces switching losses by allowing the operation of VSI at fundamental frequency. Bridgeless SEPIC with coupled inductors is designed to enable PAM control for VSI and is operated in discontinuous conduction mode (DCM) for the complete range of DC link voltage. DCM operation simplifies power factor correction control scheme to a simple voltage follower approach, since it has inherent input current shaping feature. The introduction of coupled inductors in the bridgeless SEPIC converter lowers the overall count of components, allows better integration and lowers the requirement of inductance, compared to conventional bridgeless SEPIC. OCC which is a nonlinear control technique, used in the voltage control loop, enhances the performance with improved startup and transient state response. It also improves the quality of supply current drawn by reducing the distortion compared to PI control technique. The proposed BLDC motor drive is modelled and simulated using MATLAB/Simulink. The performance of proposed system is evaluated for a wide range of speed control. The experimental prototype for bridgeless SEPIC with coupled inductors is implemented. The inherent power factor correction for supply voltage variations is validated using the results. The bridgeless operation of the converter with coupled inductor configuration is also described with experimental waveforms at rated supply voltage of 220 V. 2019, King Fahd University of Petroleum & Minerals.
Power control strategy for grid connected permanent magnet synchronous generator of a distributed generation unit
(2014) Urundady, V.; Vittal, P.K.
This paper describes the studies on the operation and control of a variable speed wave energy conversion system. The wave energy conversion system considered is oscillating-water-column (OWC) based Wells turbine driven permanent magnet synchronous generator connected to the grid by means of fully controlled frequency converter. In such systems primary aim is to achieve a low distortion, high power quality power export from the converter with the objective to regulate the power flow or power factor optimisation. In this paper wave energy conversion system is modelled and control schemes are implemented for regulating the dc link voltage for varying input conditions and for regulating the grid current entering the distribution network and hence the power flow into the grid. Response of the system is investigated under steady state, dynamic and transient conditions. In each case the grid current distortion and the dynamic performance of the converter control schemes are evaluated. Copyright 2014 Inderscience Enterprises Ltd.
Sliding Mode Controller with Integral Action for DC-Link Voltage Control of Grid-Integrated Domestic Photovoltaic Systems
(Springer, 2020) Kumar, N.B.; Urundady, V.
The grid integration of photovoltaic systems is preferred over the islanded mode of operation as the former does not require additional storage element, hence less maintenance and no chemical pollution. To regulate power exchange between the grid and the photovoltaic system, a robust DC-link voltage controller capable of withstanding the intermittent nature of solar energy and sudden variations in load is inevitable. A proportional–integral controller is used for DC-link voltage control, exhibiting oscillations during steady state and overshoot during transients. However, the conventional sliding mode controller reduces the overshoot at the expense of increased steady-state error. This paper proposes a robust sliding mode controller for DC-link voltage control to reduce steady-state error by incorporating integral action to the conventional sliding mode controller. The harmful effect of chattering phenomenon is minimised by limiting the error in the control variable using a signum function. The added features of the work include an incremental conductance method for obtaining maximum power from the photovoltaic system, instantaneous pq theory-based self-tuning filter for the extraction of fundamental component and inverter switching pulse generation using hysteresis current control technique. The grid-integrated photovoltaic system along with all features is modelled and simulated in MATLAB/Simulink platform. The results of numerical simulations carried out for various system conditions illustrate that the proposed controller provides superior performance when compared to proportional integral controller and conventional sliding mode controller in terms of harmonic compensation, power flow balance and speed of response at all system conditions. © 2020, King Fahd University of Petroleum & Minerals.