Analysis of device parasitics in a high voltage bidirectional flyback charging circuit
01 Dec 2016-pp 1-6
TL;DR: In this article, a detailed analytical model of the charging process of bidirectional flyback dc-dc converters has been established and a hardware prototype is established based on optimal charging principles and experimental results obtained from it are also presented.
Abstract: 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.
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TL;DR: In this article, an energy-based analysis and simplified energybased model for high voltage low power (HVLP) flyback charging circuits is derived, which is appropriate to describe and define the HVLP converter behavior in terms of load energy component and circulating energy component.
Abstract: Generally, battery-fed capacitive loads are charged to high voltages in series of switching cycles with smaller fragments of energy delivered to the load in every cycle to ensure an efficient charging process. In high voltage low power (HVLP) flyback charging circuit, significant portion of input energy drawn from the source in a cycle is utilized by the effective parasitic capacitance of the HV transformer and semiconductor devices and circulated back to the source at the end of the cycle. This reduces the energy delivered to the load per cycle and hence the net energy delivered in the charging process. In this paper, an energy-based analysis and simplified energy-based model for HVLP charging circuits is derived. An energy-based approach is appropriate to describe and define the HVLP converter behavior in terms of load energy component and circulating energy component. The derived energy-based model is extended to obtain analytical closed-form expressions governing the essential parameters of the charging circuit. The proposed energy-based model and analytical formulation of essential parameters are experimentally validated on a 0–2.5 kV programmable high voltage charging circuit prototype fed from 12 V input battery source.
8 citations
Cites background or methods from "Analysis of device parasitics in a ..."
...The control scheme followed in the charging phase is variable switching frequency (MVP) operation [32], [33], [36], [37] with constant PCMC....
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...Design procedure of HV flyback charging circuit with reduced voltage stress is presented in [32], [33], [36], and [37]....
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...Detailed single switching cycle based analytical model of HVLP bidirectional flyback converter, including the dominant parasitic capacitance effect, is presented in [34]–[37]....
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01 Jun 2018
TL;DR: A modular circuit structure to generate bipolar high voltage pulses from a low voltage battery source using two bidirectional flyback converter modules connected in differential manner to achieve pulses of opposite polarities respectively is presented.
Abstract: 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 ± 25 kV bipolar output voltage The experimental results observed are in good concordance with the simulation results
2 citations
References
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TL;DR: In this paper, a control which regulates the output down to zero load and maintains soft switching at light loads was proposed for a flyback DC/DC converter with 380 V/19 V, 65 W output voltage regulation.
Abstract: The soft switching of a flyback converter can be achieved by operating the circuit in the critical conduction mode. However, the critical-mode operation at light loads cannot be maintained due to a very high switching frequency and the loss of the output voltage regulation. A control which regulates the output down to the zero load and maintains soft switching at light loads is proposed. The proposed control scheme was implemented in the 380 V/19 V, 65 W flyback DC/DC converter.
111 citations
"Analysis of device parasitics in a ..." refers background in this paper
...This minimizes the switch node capacitance energy loss and peak resonant current levels [2] - [6]....
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TL;DR: In this article, a lookup table-based digital controller is applied to achieve on-line efficiency optimization by programming switching frequencies and operating modes based on the efficiency optimization processes, which is verified by experimental results on a low cost 65 W flyback dc-dc prototype.
Abstract: This paper presents an approach to efficiency optimization in digitally controlled flyback dc-dc converters over wide ranges of operating conditions. Efficiency is characterized and optimized based on power loss modeling and multivariable nonlinear constrained optimization over power-stage and controller parameters. A valley switching technique is adopted to reduce MOSFET turn-on switching loss in discontinuous conduction mode. An optimization procedure is formulated to minimize power loss weighted over a range of operating points, under a cost constraint. A lookup table-based digital controller is applied to achieve on-line efficiency optimization by programming switching frequencies and operating modes based on the efficiency optimization processes. The proposed on-line efficiency optimization approach is verified by experimental results on a low cost 65 W flyback dc-dc prototype.
109 citations
TL;DR: In this article, a flyback-type of a transformer-coupled DC/DC power converter supplies a train of current pulses to charge an energy-storage capacitor to a desired high voltage, converting input DC power obtained from a lower voltage DC source.
Abstract: A flyback-type of a transformer-coupled DC/DC power converter supplies a train of current pulses to charge an energy-storage capacitor to a desired high voltage, converting input DC power obtained from a lower voltage DC source. The energy-storage capacitor is charged to a specified voltage within a specified time with minimum peak and RMS currents in the transistor, the rectifier diode, the transformer windings and the DC power source, minimizing the i/sup 2/R losses. This is done by generating: (1) energy-storage current pulses in the power transistor and the transformer primary winding in which the current increment from the beginning to the end of a pulse is only a small fraction of the final (peak) value; and (2) energy-delivery flyback current pulses in the capacitor and the transformer secondary winding in which the current decrement from the beginning to the end of a pulse is only a small fraction of the initial (peak) value. Recommended methods are: (1) hysteretic current-mode control with current sensing in both transformer windings; (2) peak-current-commanding current-mode control with switching frequency or transistor-nonconducting time varying in a prescribed way during the charging; or (3) valley-current-commanding current-mode control with switching frequency or transistor-conducting time varying in a prescribed way during the charging. Compared with one nonoptimal method, peak currents are reduced by a factor of about 2 and i/sup 2/R power losses are reduced by a factor of about 1.33.
58 citations
"Analysis of device parasitics in a ..." refers methods in this paper
...As defined in [1] an optimal charging method is one which minimizes charging time, peak and rms currents in the switch and transformer windings to minimize the losses as well as the device ratings....
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21 Mar 2009
TL;DR: In this paper, a DC/DC converter topology for charging high voltage bulk capacitors for pulsed load applications is presented, which is a compact variant of the flyback converter with completely soft switching, variable frequency control, and optimal magnetics design.
Abstract: This paper presents a DC/DC converter topology for charging high voltage bulk capacitors for pulsed load applications. The topology is a compact variant of the flyback converter with completely soft switching, variable frequency control, and optimal magnetics design. This converter is capable of efficiently transferring power from 30 V input to a capacitor charging from 0 V to 6 kV. The specific application for this converter is a pulsed sparker for a sonobouy application, but this can apply to a large number of applications, such as defibrillators, communications, pulsed weapons systems, and industrial applications. The proposed converter was experimentally tested, and found to have peak efficiency greater than 92%, with an average efficiency greater than 89% for the entire charging cycle. The power density of the prototype is greater than 1 kW/L, with the potential to achieve 2.5 kW/L.
34 citations
TL;DR: In this paper, an HV bidirectional flyback converter for capacitive load is discussed in terms of configuration and working principle, considering the parasitic elements as well as the core loss effect.
Abstract: With the advancement of material science, various smart materials with intrinsic capacitive property are emerging. The high-voltage (HV) power electronics converters with bidirectional energy flow functionality for supplying the capacitive load are highly demanded. A switching cycle-based analytical model of an HV bidirectional converter driving capacitive load is beneficial in thoroughly understanding the operational behavior, investigating the energy efficiency, and optimizing the design. In this paper, an HV bidirectional flyback converter for capacitive load is generally discussed in terms of configuration and working principle. Considering the parasitic elements as well as the core loss effect, the converter is modeled with analytical formulas for one switching cycle. The comparison between the model-based calculation results and prototype experiments-based measurement results are used to validate the analytical model.
18 citations