Modeling, Analysis, and Implementation of High Voltage Low Power Flyback Converter Feeding Resistive Loads
TL;DR: In this article, an analytical energy-based model is derived, which includes the effect of parasitic capacitances, and is valid for steady state and dynamics of HVLP flyback converters feeding resistive loads.
Abstract: In High Voltage flyback converters, the dominant factor that influences a converter operation is the parasitic capacitance. A significant portion of input energy is utilized in charging the parasitic capacitances of the circuit, which is circulated back to the source at the end of every switching cycle. The circulating energy is a function of output voltage, load power, and parasitic capacitances and remains significant in High Voltage Low Power (HVLP) applications. This energy transfer phenomenon involving parasitic capacitances results in a reduced fraction of input energy reaching the load in every cycle, thereby resulting in an apparent deviation in the converter operating point compared to ideal flyback in case of resistive loads. An analytical energy-based model is derived, which includes the effect of parasitic capacitances, and is valid for steady state and dynamics of HVLP flyback converters feeding resistive loads. The influence of parasitic capacitances on the switch voltage of the converter is exploited to achieve Zero Voltage Switching (ZVS), thereby minimizing the turn- on loss. The proposed analytical model is verified through simulation and experimental results on 1.5 kV/ 5 W and 1.5 kV/ 200 mW resistive loads.
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13 citations
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
TL;DR: A high step-up quasi-resonant converter that minimizes switching loss over a wide range of input voltages by employing a bidirectional switch and corresponding switching modulation achieves the main switch with almost zero voltage, and therefore incurs very little switching loss at all active switches.
Abstract: This article proposes a high step-up quasi-resonant converter that minimizes switching loss over a wide range of input voltages. By employing a bidirectional switch and corresponding switching modulation, the proposed converter achieves the main switch with almost zero voltage, and therefore incurs very little switching loss at all active switches. Moreover, no instantaneous reactive current flows through the circuit under wide variations of input voltages and loads. The duty cycle of primary-side switches is fixed to 0.5; then, the input and clamp capacitor voltages become identical, and thereby the following resonant capacitor voltages remain in balance. As a consequence, the proposed converter becomes compact and achieves high boost-ratio and high efficiency over a wide range of input voltages. The operating principle of the converter is presented along with its design procedure. 400-W/380-V prototype of the proposed converter has been implemented and tested at 40–60 V to verify its effectiveness.
6 citations
DOI•
TL;DR: In this paper , a high precision primary-side regulation (PSR) strategy for the active clamp flyback (ACF) converter is proposed to deal with the non-ideal circuit characteristics as well as to enhance the control accuracy.
Abstract: The active clamp flyback (ACF) converter has been widely adopted because of the feature of isolation, soft-switching, and high conversion efficiency. On the other hand, due to the characteristic of the circuit cost reduction and the fast control response, the primary-side regulation (PSR) has become a popular control method for isolated power converters. However, high precision PSR strategies for ACF converters are not exposed. Therefore, the aim of this article is to propose a high precision PSR strategy for the ACF converter. Relations between the primary-side current and the secondary-side current are analyzed and derived. Both of the continuous conduction mode operation and the discontinuous conduction mode operation will be considered. The output voltage control mode or the output current control mode can be selected via the proposed strategy. In addition, a secondary-side losses compensation (SSLC) strategy is developed to deal with the non-ideal circuit characteristics as well as to enhance the control accuracy. Operational principles and thorough mathematical derivations will also be revealed. Finally, both simulation and experimental results obtained from a 100 W prototype circuit demonstrate the performance and feasibility of the proposed PSR and SSLC strategy. Validations show that the control accuracy of the output voltage and the output current are 98.54% and 98.42%, respectively.
3 citations
TL;DR: In this paper , a high precision primary-side regulation (PSR) strategy for the active clamp flyback (ACF) converter is proposed to deal with the non-ideal circuit characteristics as well as to enhance the control accuracy.
Abstract: The active clamp flyback (ACF) converter has been widely adopted because of the feature of isolation, soft-switching, and high conversion efficiency. On the other hand, due to the characteristic of the circuit cost reduction and the fast control response, the primary-side regulation (PSR) has become a popular control method for isolated power converters. However, high precision PSR strategies for ACF converters are not exposed. Therefore, the aim of this article is to propose a high precision PSR strategy for the ACF converter. Relations between the primary-side current and the secondary-side current are analyzed and derived. Both of the continuous conduction mode operation and the discontinuous conduction mode operation will be considered. The output voltage control mode or the output current control mode can be selected via the proposed strategy. In addition, a secondary-side losses compensation (SSLC) strategy is developed to deal with the non-ideal circuit characteristics as well as to enhance the control accuracy. Operational principles and thorough mathematical derivations will also be revealed. Finally, both simulation and experimental results obtained from a 100 W prototype circuit demonstrate the performance and feasibility of the proposed PSR and SSLC strategy. Validations show that the control accuracy of the output voltage and the output current are 98.54% and 98.42%, respectively.
2 citations
References
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TL;DR: In this article, the authors present analytical expressions for calculating leakage inductance, self-capacitance, and ac resistance in transformer winding architectures, ranging from the common noninterleaved primary/secondary winding architecture, to an interleaved, sectionalized, and bank winded architecture.
Abstract: Transformer parasitics such as leakage inductance and self-capacitance are rarely calculated in advance during the design phase, because of the complexity and huge analytical error margins caused by practical winding implementation issues. Thus, choosing one transformer architecture over another for a given design is usually based on experience or a trial and error approach. This paper presents analytical expressions for calculating leakage inductance, self-capacitance, and ac resistance in transformer winding architectures (TWAs), ranging from the common noninterleaved primary/secondary winding architecture, to an interleaved, sectionalized, and bank winded architecture. The calculated results are evaluated experimentally, and through finite-element simulations, for an RM8 transformer with a turns ratio of 10. The four TWAs such as, noninterleaved and nonsectioned, noninterleaved and sectioned, interleaved and nonsectioned, and interleaved and sectioned, for an EF25 transformer with a turns ratio of 20, are investigated and practically implemented. The best TWA for an RM8 transformer in a high-voltage bidirectional flyback converter, used to drive an electro active polymer based incremental actuator, is identified based on the losses caused by the transformer parasitics. For an EF25 transformer, the best TWA is chosen according to whether electromagnetic interference due to the transformer interwinding capacitance, is a major problem or not.
47 citations
Additional excerpts
...Several transformer winding architectures for HVLP applications are investigated in [8]....
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TL;DR: In this paper, the authors presented a digital control technique to achieve valley switching in a bidirectional flyback converter used to drive a dielectric electroactive polymer-based capacitive incremental actuator.
Abstract: This paper presents a digital control technique to achieve valley switching in a bidirectional flyback converter used to drive a dielectric electroactive polymer-based capacitive incremental actuator. This paper also provides the design of a low input voltage (24 V) and variable high output voltage (0–2.5 kV) bidirectional dc–dc flyback converter for driving a capacitive incremental actuator. The incremental actuator consists of three electrically isolated mechanically connected capacitive actuators. It requires three high-voltage (HV) (2–2.5 kV) bidirectional dc–dc converters to accomplish the incremental motion by charging and discharging the capacitive actuators. The bidirectional flyback converter employs a digital controller to improve the efficiency and charge/discharge speed using the valley switching technique during both charge and discharge processes, without the need to sense signals on the output HV side. Experimental results verifying the bidirectional operation of a HV flyback converter are presented using a 3-kV polypropylene-film capacitor as the load. The energy-loss distributions of the converter are presented when 4- and 4.5-kV HV mosfet s are used on HV side. The flyback prototype with a 4 kV mosfet demonstrated 89% charge energy efficiency to charge the capacitive load from 0 V to 2.5 kV, and 84% discharge energy efficiency to discharge it from 2.5 kV to 0 V.
40 citations
"Modeling, Analysis, and Implementat..." refers background in this paper
...Research on efficiency optimization for HVLP applications reveals that the major loss in converter operation is the switch node capacitance loss [16], [17] and is addressed by variablefrequency Quasi-Resonant (QR) mode of operation, which exploits the converter behavior and turns the active switch ON with zero voltage switching (ZVS turn-ON) [18]....
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...The inner loop includes two high-speed comparators (TLV3501), where comparator 1 compares the switch voltage (Vds) and input voltage (Vin) and generates a trigger corresponding to Vds < Vin [18]....
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...The minimum and maximum turn ratios are calculated considering reduced voltage stress on the primary MOSFET and the HV diode, respectively [18]....
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TL;DR: The Swedish Institute of Space Physics developed a miniature ion precipitation analyzer for planetary missions (MIPA) as mentioned in this paper, which was accepted to fly on board both the ESA BepiColombo mission to Mercury (2014) and the Indian Chandrayaan-1 mission to the Moon (2007).
32 citations
"Modeling, Analysis, and Implementat..." refers background in this paper
...5–3 kV to scan and focus ions of a specific energy level and is electrically modeled as a resistive load of 20–50 MΩ [2]....
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27 Sep 2004
TL;DR: In this paper, the effects of parasitic parameters in the discontinuous conduction mode of a flyback transformer in a small-sized high-voltage power supply were investigated and simulation and experimental results were provided to show the validity of the analysis.
Abstract: Modelling and analysis of the high-voltage flyback transformer utilised in small-sized high-voltage power supplies are presented. The equivalent circuit model, frequency characteristics and transient behaviour are investigated to analyse the effects of parasitic parameters in the discontinuous conduction mode. Simulation and experimental results are provided to show the validity of the analysis.
31 citations
"Modeling, Analysis, and Implementat..." refers background in this paper
...Circuit-based mode equations of HV flyback converter operating in discontinuous and critical conduction modes including the parasitic capacitance effect are presented in [13]–[15]....
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14 Mar 1999
TL;DR: A proper understanding of the influence of these parasitic components and a method that allows determination of their values will help designers optimize their power converters.
Abstract: High-frequency operation of power converters has made it clear that the parasitic components associated with power transformers have an important influence on the behavior of the converter. Leakage inductance is often considered to be the most important parameter to take into account when designing a transformer. However, when dealing with low-power applications, self-capacitance and mutual capacitance values may play a much more important role. A proper understanding of the influence of these parasitic components and a method that allows determination of their values will help designers optimize their power converters.
27 citations