M. Gopalakrishnan

A Novel Control Technique for a Multi-Output Switched-Resonant Converter

This paper proposes a novel control method for a multi-output switched-resonant converter. Output voltage can be regulated against variations in the supply voltage and load by controlling the voltage of the resonant capacitor (pulse amplitude control). Precise control is possible when pulse amplitude control is combined with pulse number control. The converter is analyzed, and design considerations are explained by using examples. Control implementation is described and load regulation and ripples are analyzed by simulation and hardware results. The topology is modified to obtain an additional negative output without any additional hardware other than a diode. The analysis of such a triple output converter with two positive outputs and one negative output is conducted and confirmed. The topology and control scheme are scalable to any number of outputs.

Multiple-integrated converters for grid-connected PV systems with intermediate DC loads

The centralized grid-connected PV systems have a serious drawback of insolation mismatch among the PV modules when a partial shadow occurs. To overcome this limitation, a decentralized grid connected PV system with multiple integrated converters (MIC) sharing a common grid connected inverter and intermediate dc loads connected through battery is proposed. The proposed multiple integrated converters are incorporated with individual MPPT controllers to track maximum power from the respective PV modules. It also increases power conversion efficiency during partial shadows when there is an insolation mismatch between the modules. The DC loads can be connected through the battery and the excess available power is supplied to the grid. The proposed configuration is simulated for various insolations and temperatures and the simulation results are presented.

Analysis and simulation of a modified single-switch bi-polar multi-output converter

This paper presents the analysis, design & simulation of a single-switch, single-input, bi-polar multi-output dc-dc converter. The proposed single-output converter generates positive low and high voltages and additionally generates a negative low voltage as well. No extra hardware is required for the additional negative output. Alternatively another converter with a high positive output voltage and a low negative output voltage is proposed with both outputs independently controllable. The proposed converter has only one switch and hence the efficiency of the system is improved due to low switching losses. Analysis, design and simulation results for the two alternative converters are presented.

A new non-isolated multi-output converter with four outputs from two switches

This paper presents a non-isolated multi-output converter with four outputs. Only two switches in a half-bridge configuration are required to generate the four outputs. More outputs are also possible without the need of any additional switch. A reference sine wave signal of a particular frequency is generated for each of the outputs. The amplitude of the sine wave is modulated based on supply and load variations. The sum of the various reference sine waves drives a half bridge converter. The square wave output from the half-bridge converter is passed through a low pass filter to minimize cross regulation between the outputs. It is then filtered using four tuned networks at the same chosen frequencies as the references and then rectified to obtain the required outputs. An analysis of the converter is done to show that control is possible by amplitude modulation of the reference sine waves. The design procedure for the resonant components is discussed and a comprehensive simulation of the converter is done for different loads and supply voltages. The results are in agreement with the expectations.

A solution for PBUC problem using payment for power delivered and power allocated method

Unit commitment in the power system schedules on/off states of generating unit that minimize the total fuel cost. In PBUC, the objective is to maximize the profit of the GENCO in the deregulated environment. In deregulated environment, GENCOs works on the bases of forecasted demand, reserve and price where the objective is to maximize their profit. The proposed method uses payment for power delivered and reserve allocated to solve PBUC problem. The proposed approach has been tested on 3 units system. The results of the proposed method have been compared with traditional unit commitment.

Fuel cell based interleaved current-fed boost converter with improved input current sharing

In this paper, a fuel cell based interleaved current-fed half bridge boost converter is presented with improved input current sharing even under a duty cycle mismatch. A separate control circuit for current sharing is thus avoided. This is achieved by using a separate clamp capacitor for each phase unlike other conventional circuits which have a common capacitor. The separate clamp capacitors acts like negative feedback and helps in keeping the input currents balanced. The converter preserves the advantages of conventional half-bridge converter such as smaller input current ripple, high gain with less transformer turns ratio etc. Simulation results based on PSpice, illustrating this idea on the proposed converter is provided.

Asymmetric dual half-bridge PWM-FM converter with quad regulated outputs

Asymmetric dual half-bridge PWM-FM converter with four outputs is discussed. Four independent regulated outputs are obtained with two legs and four switches. Among the four outputs, two are regulated through the switching frequencies of two asymmetrical half-bridge converters and the other two are regulated through duty cycles. The outputs are regulated over a wide range of input voltages and load variations. ZVS is also realized in the proposed topology. Hence it can operate with higher efficiency at higher switching frequencies. Simulation results are obtained for a converter with 48V input and 15V/16A, 12V/20A, 5V/10A & 3.3V/10A outputs.