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In this paper, a deadbeat control is proposed with reduced steady-state error in grid connected inverter system. The proposed method takes into consideration the losses occurring in the inverter during each switching cycle. Initially, a method to track the reference current is proposed and the same is extended for direct power control. The proposed method does not require phase-locked-loop, transformation into rotating reference frame and output voltage sensor thereby improving the transient response. The proposed method is verified for a single-phase grid connected switched capacitor based multilevel inverter. The simulation results of proposed current control are presented for step change in current reference. The proposed deadbeat direct power control is verified for PV connected system with varying irradiance.

Buck-Boost based full-bridge DC-DC converters possess potentials for high gain, high power applications, particularly in solar PV, battery, and fuel-cell fed systems, as the converters feature non-pulsating input and output currents. However, these converters lack attention due to the presence of DC-current in the transformer winding. In this paper, a novel Buck-Boost full-bridge (BBFB) converter with a hybrid control scheme (HCS) mitigating the transformer DC-current is presented. The BBFB converter exhibits inherent soft-switching such that zero voltage switching (ZVS) conditions apply for individual switches. This paper analyzes the BBFB converter extensively, including the discontinuous conduction mode (DCM) operation and the DCM boundary condition. A dynamic behavior of the BBFB converter under a load step change verifies that the HCS scheme does not affect the converter performance. Besides, this work presents a model for the high frequency oscillations that occur in the practical transformer current waveform due to parasitic capacitances. All the analyses and the developed models are verified in simulations and hardware experiments. The developed models are useful for designing the BBFB converter with improved efficiency by ensuring the ZVS operation. Further, the developed models and results provide an insight for the DC voltage gain variations during DCM and continuous conduction mode (CCM). This helps the designer to choose the BBFB converter’s operating mode based on the requirement.

High voltage pulses of the output power ranging from 5 W to 200 W are employed in food processing systems, water treatment process, electroporation, industrial and medical applications etc. The power converter configuration implemented to generate high voltage pulses is selected depending on the peak power rating requirement. In this work, a flyback converter configuration is selected to charge the energy storage capacitor meeting the desired voltage magnitude and charging time constraint. The energy storage capacitor is charged following peak current mode control with boundary conduction mode. In this proposed work, high voltage rectangular pulses of 1000 V magnitude with the desired pulse repetitive rate and pulse width is designed for various case studies and validated through corresponding simulation results.

Traditional SONAR (SOund Navigation And Ranging) systems use conventional rectifiers for converting the input AC voltage for fulfilling the power requirements. The disadvantage of using these rectifiers is elevated losses in the system, resulting in lower system efficiency. The total harmonic distortion (THD) and input power factor (PF) are low. Improved performance with respect to THD and PF could be obtained by using a switched-mode power converter. A soft-switching based buck-boost PFC power converter operating in DCM is proposed in this paper. The steady-state interval of operations of the proposed configuration is presented. The steady-state analysis of the proposed PFC converter is verified in simulations carried out for a full-bridge inverter system with 1 kW / 1200 V rms output fed from the proposed front end PFC converter. The simulation results are in agreement with the analysis.

A multi input bidirectional LCLC resonant converter for hybrid energy systems is proposed. The proposed converter consists of four voltage sources and transfers power from different combination of input sources to DC link based on the power availability with the sources. The converter charge the batteries in battery charging mode thus enabling bidirectional capabilities. All the high frequency operated switches in the converter turn on with ZVS in both the modes of operation. The converter achieves good voltage regulation for the load as well as input voltage variations using frequency modulation. Simulation results and design guidelines are outlined for the proposed converter.

The single-phase boost Power Factor Correction (PFC) converter has become an essential front-end converter in most power electronic systems. The need to ensure good converter performance under constraints of high power density and low costs has made converter control challenging. Deadbeat Predictive Current Control (DPCC) can offer fast control action; however, careful digital implementation is essential to ensure high performance. This paper analyses and presents the various control implementation aspects to be considered for DPCC of the single-phase boost PFC converter with the help of analytical, simulation and experimental studies.

The Series-parallel (s-p) configured Lithium ion batteries find use in many spacecrafts. Cell selection to make a battery pack involves sorting tested cells to meet screening and matching criteria. Cell capacity, cell resistance, and self-discharge could be used for cell selection. Conventionally, data is linearly sorted into ascending or descending order based on one parameter. Matching criteria are applied to choose cells to be put into strings. Cell sorting using the Genetic Algorithm (GA), involving mixed-integer linear optimization, is proposed in this paper. Cells are arranged randomly to match all of the parameters within a set of tight constraints. A better match for the cells is achieved by multiple iterations. GA Improved Cell Sorting Algorithm (GICSA) is verified with experimental data and has given close to 100% cell yield.

In this paper, a loss modulated direct power control method is proposed for a single-phase grid connected photovoltaic system. The proposed method employs the concept of adding the modulated signal corresponding to converter losses with the modulated signal corresponding to power transfer with ideal inverter. The proposed method is explained with the model of grid connected voltage source inverter with and without converter losses. The implementation of the control method does not require phase-locked-loop resulting in improved efficiency and response time. Further, an algorithm is proposed to generate the reference power required to implement the direct power control with maximum power point tracking for multisource photovoltaic system. The proposed control method and algorithm is implemented with switched capacitor based boost multilevel inverter. The simulation results under varying irradiance and reactive power are presented. The results show the good tracking performance of maximum power point along with real and reactive powers.

Finite Set Model Predictive Control (FS-MPC) of three phase Vienna rectifiers has gained popularity due to its superior control action and ability to handle system constraints. However, FS-MPC performance depends largely on the accuracy of the predictive model of the system. The presence of unmodelled converter non-idealities, parameter variations and model inaccuracies leads to input current distortions. A Moving Average (MA) based FS-MPC algorithm is proposed in this paper to improve the input current quality. The proposed MA based FS-MPC algorithm does not require the values of the converter non-idealities and their variations. The proposed MA based FSMPC algorithm is validated in simulation studies.

This paper presents a generalized predictive Discontinuous Conduction Mode (DCM) average current control law and a digital method for conduction mode detection suitable for DC-DC converters and PFC converters. The DCM current controller is derived considering the practical aspects in the digital implementation. The mode detection method does not require additional circuits/sensors. The salient control equations are derived for boost, buck and buck-boost topologies using the derived generalized equations. The derived generalized predictive DCM average current controller and mode detection method are verified in simulations for a boost DC-DC converter and experimentally on a boost PFC converter hardware prototype.

Single stage DC-AC converter with sinusoidal phase shifted full bridge converter as the front end followed by cycloconverter is commonly used for microgrid/EV applications. The operation and analysis of the converter with cycloconverter switching at line frequency and combined line/high frequency are presented in this paper. The control configuration implementation for single stage DC-AC converter with a sinusoidal phase shifted front end followed by a cycloconverter is presented which ensures soft transitions for all the semiconductor devices. The comparison of line frequency switching and combined line/high frequency switching of cycloconverter devices of single stage DC-AC converter in terms of performance and efficiency is presented. Analytical expressions for the computation of losses in the cycloconverter switched at line frequency and combined line/high frequency are proposed. The control, analysis, and mathematical expressions are verified in simulations and 500 W single stage DC-AC converter experimental prototype.

In this paper, a shifting carrier based maximum power point tracking (MPPT) algorithm for multisource converters is proposed. This MPPT algorithm is explained for both low frequency (constant carrier) and high frequency (triangular) carrier signals. The proposed algorithm is applied for a single stage multisource switched capacitor based multilevel inverter for grid connected and stand-alone photovoltaic applications. This converter features high gain, less component count, self capacitor charge balancing, better dispersed value of sources and increased source utilization. The importance of selecting an appropriate pulse width modulation technique for switched capacitor based inverters in order to maintain the capacitor charging time is explained. The proposed technique is able to track the maximum power under varying irradiance levels. The experimental results of the proposed algorithm is presented. The MPPT technique is analyzed and verified in simulation for stand-alone and grid connected applications using MATLAB/Simulink platform.

The paper presents the steady-state analysis of the step-up/step-down operation of the full bridge resonant transition converter (FBRTC). In spite of several work being reported in the literature on the FBRTC converter, the performance differences during the step-up and step-down operations are less investigated. Influence of leakage inductance, magnetizing current of the transformer and switching frequency on the steady-state DC-voltage gain of the step-up/step-down converters is presented with the supporting results. The iterative design methodology for the step-up/step-down converters are proposed to enhance the efficiency. The investigation carried out in this work help the designer to select the appropriate leakage inductance, magnetizing inductance, turns ratio of the transformer and switching frequency of the step-up and step-down converters. The analysis and design methodology are validated in simulations. The performance analysis is verified in a 500 W experimental prototype.

Ion mass analyser is an analytical space instrument employed to characterise the spatial ions. The guiding plates of the ion mass analyser require high voltage drive in the range of 0–5kV and is powered by a low voltage battery source. Flyback converter is widely employed for high voltage low power charging applications, fed from low voltage input source. Implementation of conventional flyback converter topology demand semiconductors of high voltage blocking capability greater than 5 kV to ensure 0–5kV charging and discharging process. Considering the limited commercial availability of high voltage active semiconductors at the operated low power level (

In this work a simple, analytic model is proposed to estimate the depth-dependent temperature profile in multilayered power electronic systems. The proposed model considers both upward and downward heat flow, with heat conduction within the structure and heat convection at the heat sink boundaries. The proposed model is verified with simulations and experimental data obtained on multi-layered power devices like solar cell and a power converter having an insulated gated bipolar transistor (IGBT) and a diode. Besides being computationally efficient, the proposed analytical model predicts the temperature profile as accurate as obtained from commercial numerical simulators. The experimental verification of the model for a multi-layered solar cell structure is also presented.

The design of the current control loop in a boost PFC converter plays a significant role due to the large signal variations in the input waveforms. A predictive average current control law based on triangular modulation considering the converter non-idealities, time variation of waveforms and computation delays is proposed and validated with simulation and experimental results. A digital method for the boost inductance value estimation is also proposed which could be used with predictive current control laws.

A high gain, single-stage DC-AC converter with high frequency AC link is proposed in this paper. The single-stage DC-AC converter has the advantage of high efficiency, less component count and high power density. The proposed converter consists of a high frequency switching buck-boost bridge followed by a low frequency switching cycloconverter. A hybrid sinusoidal PWM switching scheme is used for the buck-boost bridge to control the output and to mitigate the DC-current in the transformer primary winding. In the proposed converter, soft transition is achieved in all the devices. The steady-state voltage gain achieved is twice that of the conventional H-bridge phase-shift converter. The input current is continuous in the proposed converter which reduces the DC bus capacitor requirement for solar PV fed applications. The steady-state analysis with the modes of operation of the proposed converter are presented. A 2 kVA proposed converter feeding the R and RL load is designed and implemented in the simulations and the analytical model is verified. The comparison studies of the proposed converter with the topologies in literature are presented.

This paper presents a control scheme for achieving improved efficiency in a H-bridge buck-boost DC-DC converter. The H-bridge buck-boost converter with conventional control scheme operates at lower efficiency compared to buck and boost converter for the same step down/up action, due to the absence of direct power component. A control scheme is presented in this paper to achieve better efficiency by introducing maximum direct power component without affecting the steady state voltage gain. A hardware prototype of 500 W is tested with the proposed control scheme and an efficiency improvement of 4 % is observed as compared to that of the conventional control.

Spacecraft is generally powered by solar array and battery. The design of power system considers that the energy supported by battery is put back in sunlit while catering to other spacecraft loads. The energy balance estimation over multiple cycles is essential to ensure proper functioning of spacecraft. In this paper, a generic model is developed for estimation of energy balance. Proposed model takes battery configuration, cell open circuit voltage characteristics, resistance characteristics, load profile, generation profile as inputs. Battery voltage, resultant battery current, State of Charge (SOC) and instantaneous internal resistance are output. In a two-step procedure, battery health parameters are estimated and then estimated parameters are used to check energy balance over new load and generation profiles. The load and generation profiles are run in loop helping in establishing stabilized battery voltage (positive energy balance) or voltage walk down over several cycles (negative energy balance). The proposed model is verified with experimental data and is in close agreement.

In this paper, the state-space averaged small-signal model is derived for a non-isolated single-input-multi-output (SIMO) DC-DC converters. When the dynamics of the converters are governed by switched ordinary differential equations (ODEs), the averaged model can be derived through traditional methods. The modelling challenge in non-isolated SIMO converter arises from the differential algebraic nature of the circuit. Here the traditional methods cannot directly be applied. This is addressed using the quasi-Weierstrass transformation (QWT) which transforms the switched DAE system to an equivalent switched ODE system. A small-signal averaged model is obtained for the transformed switched ODE system using the notion of consistency projectors. We take the Zeta-Buck-Boost converter (ZBB) as an example and derive the small signal state-space averaged model for it. Simulations are performed to compare the time-response of the states corresponding to the switching circuit and the small-signal averaged model. A hardware setup of Zeta-Buck-Boost converter is designed and the proposed dynamic model is verified experimentally.

Planar Transformers are popularly used over conventional wire wound transformers for its design accuracy, high power density and low parasitics. For high voltage low power (HVLP) flyback converter with high switching frequency feeding a capacitive load, the leakage inductance and self-capacitance of the transformer along with other semiconductor parasitics significantly affect the performance of the converter. Different transformer winding architectures are explored to choose a transformer design with minimum parasitics. In this paper, rectangular winding planar transformer is evaluated for non-interleaved winding architecture and the spiral winding planar transformer for a high voltage low power flyback converter is evaluated for non-interleaved and interleaved winding architectures. The analytical expressions for leakage inductance and self-capacitance are verified using the frequency response analyzer (FRA) and Finite Element Analysis (FEA) simulation results. The difference in the results obtained from analytical, 2D FEA and measurement results are compared. The designed HVLP rectangular and spiral winding PT is fabricated and tested with high voltage flyback converter prototype for 1 kV/5 W. The analytically computed parasitics of the transformer is verified with FEA model and also from the experimentally observed waveforms.

In the full-bridge converter, DC-current in the transformer exists due to unequal forward voltage drops in the semiconductor devices. A conventional peak current mode control is used to mitigate this DC-current in duty controlled full-bridge converter. In phase-modulated full-bridge converter, unlike duty controlled converter, conventional peak current control is not viable to mitigate the DC-current. A novel control scheme to mitigate this DC-current is proposed which retains the performance characteristics of the converter. With the proposed control scheme, output regulation and DC-current mitigation are implemented in a decoupled manner, therefore output voltage is unaltered during the process of DC-current mitigation. The impact of variations in on-state resistance of the lagging and leading leg MOSFETs on the DC-current magnitude is analyzed. From the analysis, it is observed that the variation in the on-state resistance of the lagging leg MOSFETs causes larger DC-current compared to leading leg. The simulation and experimental results verifying the proposed control scheme is presented.

The single phase boost PFC converter is used as a front end stage in equipments in order to conform to harmonic standards. Due consideration is to be given for the implementation issues in the boost PFC converter due to the large signal variations in the converter waveforms and its wide operating ranges. This paper highlights the practical challenges and implementation aspects with respect to the topology and control in a single phase boost PFC converter. The causes of input current distortion and conduction mode change are analysed. The effect of voltage loop bandwidth on the converter performance is discussed. Digital implementations with PI current controller and with predictive current controller are discussed. Inferences are presented based on equations and experimental results. The experimental tests are carried out on a 50 Hz universal AC input, 400 V DC output, 300 W single phase boost PFC converter hardware prototype operated at a switching frequency of 100 kHz.

This paper presents a modular circuit structure to generate bipolar high voltage pulses from a low voltage battery source. Smart material based actuators and ion analysers require bipolar high voltage output in the range of ± 1 kV to 3 kV for their effective operation. In this paper, two bidirectional flyback converter modules are connected in differential manner to achieve pulses of opposite polarities respectively. Dedicated CPLD control cards are designed to govern the operation of individual module. Each module operate with a two loop control scheme where inner loop detects Minimum Voltage Point (MVP turn on) and output loop controls the peak charging current. The modules operate in a phase shifted manner with control signals communicated between the individual controllers to ensure module level coordination. An experimental prototype fed from 12 V input is designed and control scheme is implemented to obtain ± 2.5 kV bipolar output voltage. The experimental results observed are in good concordance with the simulation results.

Boost type front end Power Factor Correction (PFC) converters are used to obtain a sinusoidal input current which is in phase with the input sinusoidal voltage while at the same time maintaining the output voltage constant. This front end stage is required to conform to harmonic norms. Unlike a DC-DC boost converter with small signal input variations about the quiescent operating point, the boost PFC converter is subjected to large signal variations in every half line cycle. In this paper, the nature of these large signal variations and effect of a linear controller in this converter is analyzed. Further, certain issues that lead to performance degradation in the converter are highlighted based on simulation results.

In high voltage (HV) flyback charging circuits, the importance of transformer parasitics holds a significant part in the overall system parasitics. The resonance between magnetising inductance and resonant capacitance cause significant deviations in voltage gain. This effect is predominant in the case of very lightly loaded high voltage flyback converters when used for bipolar output voltages. In this paper, two circuit configurations are proposed to obtain the bipolar output voltage from a high voltage(HV) flyback for lightly loaded circuits. The operational similarities and the advantages/limitations of the two configurations are presented. The effect of transformer winding capacitance on the achievable gain in a bipolar operation is analysed in both the approaches. The analysis is verified in simulation and hardware implementation for high voltage bipolar flyback converters with valley mode switching to achieve minimum switching loss and device stress.

This paper presents hardware implementation of a quasi-resonant bi-directional flyback converter (QR-BFC). The design of power stage, control stage and feedback sensing stage is presented specifically for a low power high voltage capacitive load charging and discharging application. The design objective is to achieve faster charge and discharge process with high efficiency, small size and low cost. The converter operates in three modes — charge, discharge and burst mode. Power stage design presents guidelinies for selection of power stage elements of the converter. The control stage design presents implementation of a minimum voltage point (MVP) switching logic of primary and secondary MOSFETs by use of basic logic gates in a low cost CPLD. The isolated feedback sensing design stage presents a resistive capacitive divider circuit for implementation of burst mode voltage regulation. Experimental results are presented with a hardware prototype design.

Bidirectional flyback dc-dc converters are widely used for low power capacitive load charging. The performance of such converters are highly dependent on device parasitics which are mostly capacitive in nature. Implementation of soft switching methods like first resonant valley mode switching exploit their presence to minimize the device stress and loss. However in the process, these parasitic capacitances consume some energy supplied from the source. This trapped energy becomes significant at high operating voltage. In this paper a detailed analytical model of charging process of such converters has been established. The analytical model is used to show the role of parasitic capacitance in limiting the maximum achievable output voltage. A hardware prototype has been established based on optimal charging principles and experimental results obtained from it are also presented.

A significant influence of parasitics is perceived in high voltage low power flyback converters. The sinusoidal resonance between the magnetising inductance and the parasitic capacitance results in apparent deviations in voltage gain unlike the conventional flyback converter. This effect is predominant in case of very lightly loaded converter where the major portion of the input energy is consumed in charging the parasitic capacitances. The paper presents an analytical expression for steady state voltage gain of flyback converter in high voltage low power applications. Insight on sinusoidal resonance between the magnetising inductance and the parasitic capacitances is outlined and the effects of converter operating with fixed frequency is addressed. Profile of converter voltage gain and switch stress with variation in switching frequency is examined from which a range of frequency which offers optimal gain along with zero voltage stress during turn on is observed. A control scheme which deploys variable switching frequency thereby facilitating Zero Voltage Switching is investigated. Analysis of converter employing zero voltage switching scheme is carried out and the analytical equations governing the operation are derived. Simulation model and hardware prototype is built to validate the analytical results.

In high voltage (HV) flyback charging circuits, the importance of transformer parasitics holds a significant part in the overall system parasitics. The HV transformers have a larger number of turns on the secondary side that leads to higher self-capacitance which is inevitable. The conventional wire-wound transformer (CWT) has limitation over the design with larger self-capacitance including increased size and volume. For capacitive load in flyback charging circuit these self-capacitances on the secondary side gets added with device capacitances and dominates the load. For such applications the requirement is to have a transformer with minimum self-capacitances and low profile. In order to achieve the above requirements Planar Transformer (PT) design can be implemented with windings as tracks in Printed Circuit Boards (PCB) each layer is insulated by the FR4 material which aids better insulation. Finite Element Model (FEM) has been developed to obtain the self-capacitance in between the layers for larger turns on the secondary side. The modelled hardware prototype of the Planar Transformer has been characterised for open circuit and short circuit test using Frequency Response Analyser (FRA). The results obtained from FEM and FRA are compared and presented.

The phase modulated full bridge resonant transition converters are widely used for high gain, high power applications. For such applications, the difference in the output voltage predicted from the lossless DC gain model and the actual output voltage is significant. Hence the DC gain loss model for this converters is proposed and analyzed in this paper. The six intervals of operation of the converter are analyzed with non-ideal parameters like winding resistance (R L ) of the output filter inductor, on-state resistance (R on ) of MOSFETs, resistance (R diode ) and forward voltage drop (V D ) of output rectifier diodes. The DC gain loss model is derived from the analysis of these intervals. The optimal choice of turns ratio and switching frequency based on the proposed DC gain loss mode is presented. The proposed DC gain loss model is validated in the simulations. The experimental prototype for 250 W is implemented, verifying the model and design presented in this paper.