Bhoopendra Kumar Singh

GENETIC VARIABILITY, INHERITANCE AND CORRELATION FOR MINERAL CONTENTS IN CABBAGE (BRASSICA OLERACEA VAR. CAPITATA L.)

Abstract Brassica vegetables are important sources of dietary minerals. However, information on the inheritance and correlation for content of mineral elements such as iron, zinc, copper, manganese, potassium, and calcium in cabbage, which is essential if the quality of this vegetable is to be improved through breeding, is not available. Therefore, the experiment was set up with seventy-one cabbage genotypes including cultivars, germplasm and F1 hybrids grown in field. Mineral composition of the genotypes tested differed highly significantly indicating the presence of adequate amount of variability. A high heritability (>80%) accompanied by high genetic advance as percentage of mean (>40%) for uptake and accumulation of Fe, Zn, Cu, Mn and Ca indicates the predominance of additive gene, which could be improved by hybridization followed by selection breeding approach. Nevertheless, heterosis breeding would be an imperative in increasing the K content in cabbage heads as indicated by non-additive gene action for K accumulation having high heritability (>80%) and low genetic advance as percentage of mean (<30%). Moreover, both additive and non-additive genes were responsible for individual head weight. A positive correlation for Fe, Zn and Mn contents with other minerals will help in simultaneous selection of mineral elements. Nevertheless, major yield contributing ‘head weight’ was negatively correlated with minerals content and emphasized the selection of smaller head size to maintain the higher minerals content in tissues of cabbage heads. Hence, assessing the heritability, inheritance and correlation for minerals would be useful in the developing mineral-rich and productive genotypes.

220W DC-DC converter for aerospace applications

This paper addresses design issues involved in development of high voltage DC-DC converters such as optimizing isolation transformer parameters (leakage, proximity and Skin Effect), Power MOSFET losses and achieving tight voltage regulation (0.1%) used in Transmit Receive Multi Modules (TRMM). A modified transformer interleaving winding technique is implemented to reduce Skin, Proximity and leakage inductance which are associated with high voltage and high frequency. The proposed techniques are implemented in a proto type of 220W dc-dc converter designed with RCD forward converter topology with current mode control. Silicon Carbide (SiC) MOSFETS are used to improve efficiency of converter. 220W dc-dc converter is having the features of very good regulation (<;0.1%), Ripple and Spike Voltage (<;1%) and high Efficiency (>75%) in all operating conditions and meets MIL-STD-704E/F. The proto is developed in dimensions of 125mm×60mm.

Multiple-output magnetic feedback forward converter with discrete PWM for space application

This paper is aimed at design and development of fixed high frequency Forward Converter Topology operating at resonant reset mode for Space applications. This self-resonant reset mechanism eliminates power loss in the reset circuit, thus simplifying circuitry and increasing efficiency. The galvanic isolation between input and output is implemented with magnetic feedback which is insensitive to component tolerance, radiation and has good temperature stability. Due to unavailability of radiation hardened PWM IC at higher frequency (>500 KHz), discrete PWM controller has been implemented. Hence, magnetic feedback and discrete PWM controller meets the requirements of radiation for DC-DC Converter for space application. The proposed topology is demonstrated with an experimental prototype that delivers three outputs 5V/4A, ±15V/0.667A from an 18-50 V input with better than 75% at full efficiency.

Multiple output forward DC-DC converter with Mag-amp post regulators and voltage feedforward control for space application

This paper aims at design and development of multiple output forward converter with magnetic amplifier (Mag-amp) post regulators and voltage feed forward control for space application. Mag-amp regulates the output against any load variations and provides good load regulation. Voltage feed forward control is used to achieve good line regulation as the duty ratio varies directly as the input voltage. The converter is operating at a fixed frequency of 200 KHz. This paper also covers specification, design challenges and design procedure. A prototype model is developed and experimental results are validated under various operating conditions.

Multiple output forward DC-DC converter with regenerative snubber for space application

Energy regenerative snubber for forward converter topology is presented. The proposed snubber is non-dissipative as it does not contain any resistive element. It is capable of resetting the transformer core along with reducing the spike across the power switch due to leakage inductance of the transformer. It exploits the transformer leakage inductance beneficially in resetting the transformer core. This snubber recovers the energy back to the power source. This snubber can also be adapted to other transformer isolated topologies. The paper presents theoretical analysis and experimental results.

Design and implementation of quad-output flyback converter for space applications

This work is focused on design, analysis and implementation of current mode controlled, quad-output flyback converter. The design of proposed converter illustrates the achievement of tight line, load and cross regulation by using post regulators. The proposed converter is operated at a switching frequency of 100 KHz. The UC1846 PWM controller is used which has features of pulse by pulse current limiting and soft start capability and under voltage lockout with current mode control technique. A separate bias winding is used for converter loop feedback and also start-up circuit is used to enhance soft start in converter. Primary side current mode control scheme is achieved by comparing input inductor current with bias winding output to modulate the width of pulses generated from PWM controller. The proposed converter is implemented on a hardware prototype with a quad-output using the input voltage range from 65-75V with an efficiency greater than 50%. This converter has protection circuits such as under voltage protection as well as over current protection and current fold back circuit and inbuilt EMI filters.

Design and implementation of current mode controlled 150W miniature forward converter for defence application

This paper aims at design and implementation of light weight, smaller size, highly efficient and reliable single output DC-DC converter for defence application. To achieve miniaturization of the converter high switching frequency is selected, which in turn reduces the mass, size of magnetic and output filter components‥ To overcome the limitation of 50% duty cycle in auxiliary winding reset forward converter, RCD reset forward converter is designed and implemented to provide 55% duty cycle at the lower side of the input to deliver 30V/5A. Proposed converter is designed using RCD reset forward converter of switching frequency 150 kHz using UCC28C43 as a PWM controller. The proposed converter delivers 30V/5A from a 15V–45V input voltage range with efficiency better than 75%. The efficiency is greatly improved by clamping the MOSFET voltage stress from 150V to 94V at maximum input voltage. The proposed topology is realized with an experimental prototype of size 112 mm × 65 mm × 15mm.

Design and implementation of Current mode controlled multiple output flyback converter for military applications

This paper is aimed at the design and implementation of a high frequency, multiple output, and miniaturized converter for military applications. The implementation is done using the flyback topology in order to make the converter module compact. The proposed converter design illustrates how to achieve better line, load and cross regulations using post regulators. The converter is operated at a switching frequency of 400 KHz using UC1843 PWM Controller. A separate output bias winding is used for converter loop feedback. Primary side Current mode control scheme is attained by comparing input current with bias winding output to modulate the width of the pulses generated from PWM circuit. The converter is validated with an experimental setup which delivers three outputs with desired efficiency of 70%. A delay circuit is employed to maintain the time delay between the outputs. The flyback converter design is equipped with start-up series pass regulator circuit, inrush current limiting circuit, under voltage as well as over current protection circuits.

A Feed forward Voltage Mode Controlled ZVS based Phase shifted 300W full bridge DC-DC converter for military application

This paper is a conversion solution to an advanced development of critical power supply systems in military application. A compact size high power density i.e. 25.26 watt/inch3 DC-DC converter is designed and developed. An appropriate topology of a ZVS based Phase Shifted full -bridge DC-DC converter is selected based on advantages of reduced switching losses and stresses with fixed switching frequency of 100KHZ. A PWM Controller UC1875 is used which has features of programmable output delay for resonant switching action with both voltage and current modes of controlling options. A feed forward voltage mode control is utilized which is easier to design and analyze with good noise margin and stable modulation process and improved line regulation. The Proposed topology is implemented on a hardware prototype with a single output of 30V/10A using input voltage that ranges from 18-36V with an efficiency greater than 80%. An opto-isolation is provided instead of transformer for feedback loop to minimize the size, complexity and cost. A fault tolerant design, this converter host circuit protection features such as over voltage, over current, efficient thermal protection and inbuilt EMI/EMC filters. The converter is realized in a very small size of 102mm×92mm×20.5mm aluminum package.

Design and development of high frequency 360Watt RCD clamp forward converter for radar applications

This paper deals with design and development of high frequency, high power Resister, Capacitor and Diode (RCD) clamp forward converter for Radar application. RCD clamp reset technique is used to reset the energy stored in the transformer during turn off. It is less expensive than using a tertiary winding, and as it allows duty cycle excursions above 50% and it greatly improves the behaviour in half-cycle dropout tests. The Converter is operating at a fixed frequency of 350 KHz with current mode control technique. Two transformer approaches is used to reduce the power loss and to increase efficiency. The UCC28C43 current mode controller is used as PWM controller to drive the switching MOSFET. The Optocoupler is used in the feedback control circuit for the purpose of isolation and hence it reduces the circuit complexity. This paper also deals with the specifications, design challenges and design procedure. Prototype model is developed and is tested to deliver the regulated output of 12V/30A with 270V input DC bus with efficiency ≥80%.