Faculty Publications
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Item Selection of electric drive for EVs with emphasis on switched reluctance motor(CRC Press, 2023) Pittam, P.K.; Parthiban, P.; Kalpana, R.Different electrical machines have been investigated to check their suitability for electric vehicle (EV) applications. The interior permanent magnet synchronous motor (IPMSM) and brushless DC (BLDC) motor are widely employed in EVs due to the use of permanent magnets (PMs), which provide high torque density and better efficiency. Therefore, PM machines are the preferred choice for applications where a high-efficiency motor is required. However, manufacturers are interested in finding an alternative to PM machines to avoid the issues related to rare-earth magnets. Induction machines (IMs), switched reluctance machines (SRMs) and synchronous reluctance machines (SyncRels) are gaining importance for EVs due to the lack of PMs. The simple and low-cost construction due to lack of PMs or windings on the rotor makes the SRM a potential candidate for EV applications in preference to PM machines and IMs. SRMs are more reliable in high-speed and high-temperature operation due to the absence of rotor excitation. The price volatility, environmental concerns and supply chain issues of rare-earth magnets present in PM machines have become a long-running problem in producing high-efficiency motors [1]. However, the absence of rare-earth magnets in SRMs is an advantage in this aspect. Rotor displacement and rotational stress limit the performance of PM motors in high-speed operation due to excessive centrifugal forces, which cause stress to develop in magnet slots and bridges. However, SRMs can be operated at high speeds due to the lack of slots and bridges in the rotor. The performance of PM machines deteriorates during field-weakening operation, whereas in SRMs, field weakening is a natural phenomenon at high speed. Moreover, SRMs have a wide constant power-speed range compared with PMs and IMs. IMs suffer from rotor copper losses due to the use of die-casting aluminium for rotor conductors, which limits high-temperature operation; usually, copper die-casting is used at high temperature, and this involves an expensive and challenging manufacturing process. Moreover, the independent torque production capability of each phase due to the electrical isolation of each phase endows SRMs with a fault-tolerant nature. In spite of all these advantages, SRMs suffer from high torque ripple, noise and vibration. However, torque ripple doesn't exclude the adaption of SRMs for EV applications; several significant contributions have been made towards torque ripple minimization by modifying rotor geometry and optimized control of phase current. The selection of the electric drive is the crucial step of EV design. This chapter deals with selection criteria and a comprehensive understanding of performance characteristics of different electric drives widely used in EV applications, including PM machines, IMs and SRMs. This chapter mainly deals with how the control principles have been evolved for SRMs to meet the requirements of EV adaption and briefly discusses the control methods established for performance enhancement, such as torque ripple minimization and torque to ampere ratio improvement. This chapter also deals with the adaption of direct torque control (DTC) to SRMs and analyses the reasons behind negative torque generation in phase. This chapter includes recent contributions towards the evolution of DTC over a period of time in terms of sector reorganization, voltage vector reformation and optimized voltage vector selection. This chapter also presents simulation studies of conventional and modified versions of DTC. © 2023 selection and editorial matter, Dharavath Kishan, Ramani Kannan, B Dastagiri Reddy and Prajof Prabhakaran; individual chapters, the contributors.Item Performance evaluation of multi-input converter-based battery charging system for electric vehicle applications(CRC Press, 2023) Kalpana, R.; Kiran, R.; Parthiban, P.This chapter address a dual-input half-bridge DC–DC converter with semi-active full-bridge rectifier at secondary. The proposed configuration is satisfactory to provide power supply to load and instantaneously charge the battery. The proposed configuration has three stages. It includes input variable sources; the isolation stage consists of two HFTs (High Frequency Transformer), and the rectifier stage consists of a semi-active full-bridge rectifier at secondary with a bidirectional buck boost converter for charging and discharging the battery. Complete steady-state analysis and design of the converter have been investigated. An FPGA-based controller was used to implement digital closed loop control in order to minimize the control strategy's complexity. A constant current/constant voltage (CC/CV) mode of control algorithm has been implemented for charging the battery in order to achieve higher efficiency and protection of the battery. The battery charging current is controlled by the output current control loop and has low output voltage ripple, which leads to high efficiency of the system. To confirm the feasibility of the proposed system, an experimental prototype has been developed. Extensive tests have been carried out under varying loads and different input voltage variations. Compared with standard systems, the proposed system has an improved capacity to utilize different sources of power. © 2023 selection and editorial matter, Dharavath Kishan, Ramani Kannan, B Dastagiri Reddy and Prajof Prabhakaran; individual chapters, the contributors.Item Electric energy sources and storage device(Institution of Engineering and Technology, 2024) Kalpana, R.; Manjunath, K.; Chiliveri, V.R.; Kiran, R.[No abstract available]Item An improved power quality converter for three-phase switched mode power supplies(IEEE Computer Society help@computer.org, 2014) Kalpana, R.; Singh, B.; Bhuvaneswari, G.In this paper, an improved power quality converter is presented for harmonic mitigation in SMPS (Switched Mode Power Supply) for telecom power applications with reduced kVA rating. The proposed ac-dc converter is found capable of suppressing less than 23rd harmonic in the supply current along with the power factor improvement close to unity in the wide operating range. The effect of load variation on the SMPS is studied to demonstrate the performance and effectiveness of the improved converter. © 2014 IEEE.Item High-efficiency improved 12kW switched mode telecom rectifier(Institute of Electrical and Electronics Engineers Inc., 2016) P, P.; Kalpana, R.; Singh, B.; Bhuvaneswari, G.In this paper an improved switched mode telecom rectifier for a 12kW telecommunication system is presented. An improved telecom rectifier is a combination of phase-shift transformer based ac-dc converter and passive high pass filter. The phase-shift transformer and high pass filter is realized with a fractional magnetic rating of the load. The supply current is almost sinusoidal with low total harmonic distortion, and the power factor (PF) is close to unity. The complete design of phase-shift transformer based ac-dc converter and passive high pass filter is presented in this paper. The 12kW telecom rectifier is designed, modeled and simulated to reduce the total harmonic distortion (THD) of the input ac mains current and to improve the power factor. A laboratory prototype of phase-shift transformer based ac-dc converter is developed and the results are presented to validate the design topology. © 2015 IEEE.Item Configurations of modular push-pull buck DC-DC converters for 12KW telecom SMPS and its design(Institute of Electrical and Electronics Engineers Inc., 2016) P, P.; Kalpana, R.In this paper the push-pull buck DC-DC converter topologies are presented for 12kW telecom power supply. They have some attractive features compared to boost converters such as meeting the requirement of varying controllable output dc voltage, inherent short-circuit protection, and easy control of inrush current. Their input currents can be controlled in the open loop and much wider voltage loop bandwidth can be achieved. The proposed modular converter is modeled and its various configuration performance is simulated in MATLAB environment along with SIMULINK and Sim Power System (SPS). © 2016 IEEE.Item High performance three-phase PFC rectifiers for telecom power supply(Institute of Electrical and Electronics Engineers Inc., 2016) P, P.; Kalpana, R.Generally telecom power supply requires higher efficiency from the ac input mains to the load end. So the front-end power factor correction (PFC) rectifier should show very high efficiency. In this paper, the front-end ac-dc converter having a boost type PFC rectifier which is a logical solution to the telecom applications is proposed. The Minnesota rectifier and Delta Switch rectifier are discussed for the front-end PFC converter which can be used for power quality improvement. Then the output of PFC rectifier is given to the three-phase high frequency dc-ac converter which intern drives the high frequency transformer (HFT) and produces the voltage level of 60V and 100A. These whole front-end and back-end converter configurations are classified as hybrid telecom power supply. The performance of front-end three-phase PFC rectifier with the back-end dc-dc converter configuration is simulated in the MATLAB Simulink environment and the results are presented in order to validate the design. © 2016 IEEE.Item Improvement in Harmonic Reduction of Zigzag Autoconnected Transformer Based 12-pulse Diode Bridge Rectifier by Current Injection at DC Side(Institute of Electrical and Electronics Engineers Inc., 2017) Vidyasagar, V.S.; Kalpana, R.; Singh, B.To improve the harmonic reduction ability in input line current of 12-pulse diode bridge rectifier (DBR) using zigzag autoconnected transformer with a dc side current injection technique is presented in this paper. Conventional 12-pulse rectifier does not meet the IEEE-519 standard and therefore current injection technique at dc side is used to shape the system current waveform to minimize the harmonic distortion in the input line current. The proposed configuration uses zigzag autoconnected transformer with inherent ability of blocking zero-sequence components which eliminate the requirement of zero sequence blocking transformer (ZSBT). The current injection circuit with interphase reactor (IPR) enables to alter dc current at the rectifier output which further shapes input line currents to near sinewave. The proposed configuration is designed, simulated and analyzed in MATLAB/SIMULINK. Simulation results of proposed configuration for variation in current injection and load on input line current harmonic suppression, power quality parameters are presented in this paper. © 2016 IEEE.Item High performance front-end PFC rectifier for telecom power supplies(Institute of Electrical and Electronics Engineers Inc., 2017) P, P.; Kalpana, R.; Singh, B.; Bhuvaneswari, G.High-current low-voltage (HCLV) rectifiers are used in the telecom industries, electroplating and induction heating system. Typical power rating of these rectifiers varies from tens of kW to hundreds of MW. In this paper, a three-phase three-level boost type PWM rectifier is proposed as an active front-end PFC scheme for telecom load. The proposed active front-end PFC converter is modeled by switching cycle average model and relation between duty ratio and the dc-link capacitor voltage is derived as in terms of system input currents. Also, the switching states have been derived for the feasible converter operation. The detailed analysis of front-end PFC converter is carried out by equivalent circuit. The power quality also well improved by proposed active front-end PFC rectifiers. The experimental setup for a 12 kW active front-end PFC rectifier is developed in the laboratory to validate the MATLAB simulation results. © 2016 IEEE.Item Current injection based front-end power quality improved converter for telecom load(Institute of Electrical and Electronics Engineers Inc., 2017) P, P.; Kalpana, R.; Singh, B.; Bhuvaneswari, G.In this paper a front-end converter having third harmonic current injection technique is used for improving input current shape as near sinusoidal. Here zig-zag transformer is used as the current injection device so that the advantages pertaining to zig-zag transformer is utilized effectively. The third harmonic current injection device along with the three-level boost converter at the output stage will increase the dc-link voltage and the current is injected through zig-zag transformer. The power quality is well improved using third harmonic current modulated front-end structure which is very well applicable to telecom load having the high current low voltage. Extensive simulation is carried out for the 12 kW load and the results are verified through experimental setup. The experimental setup is tested for reduced voltage rating and the test results are presented. © 2016 IEEE.