Normalized statical analysis with frequency and load variation for the class-E converter based on piezoelectric transformers

Piezoelectric transformers (PTs) allow the design of promising power supply applications, increasing efficiency, reducing size, facilitating the achievement of high transformation ratio, besides providing high immunity against electromagnetic noise. Due to the electrical equivalent model having resonant characteristics, some resonant topologies are used to build these power supplies, i.e. the Class-E converter. In order to make easier the analysis of high order converters, it's possible to use a normalized analysis method. The control of the Class-E converter using PTs is implemented through the switching frequency and duty cycle variation. The static gain is achieved though the switching frequency variation, while the duty cycle is adjusted with the purpose of achieving soft switching for different frequencies and loads. This paper shows a normalized analysis of this process, including a normalized frequency and load variation, without the need of design parameters. Experimental results for a 3W step-down converter are shown for a universal 85-260VAC input and out put voltage 6 V DC, to validate the proposed method.

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Comparison of Control Concepts for Off-Line Power Supplies using Piezoelectric Transformers in Class-E Topology

37th IEEE Power Electronics Specialists Conference ◽

10.1109/pesc.2006.1712118 ◽

2006 ◽

Cited By ~ 3

Author(s):

S. Nittayarumphong ◽

F.E. Bisogno ◽

M. Radecker ◽

A.V. Carazo ◽

H. Guldner ◽

...

Keyword(s):

Power Supplies ◽

Piezoelectric Transformers ◽

Class E

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Switching Losses in a SiC-Based DC-DC Multilevel Boost Converter

Materials Science Forum ◽

10.4028/www.scientific.net/msf.717-720.1241 ◽

2012 ◽

Vol 717-720 ◽

pp. 1241-1244

Author(s):

Omid Mostaghimi ◽

Nicolas G. Wright ◽

Alton B. Horsfall

Keyword(s):

Duty Cycle ◽

Conversion Ratio ◽

Design Parameters ◽

Switching Frequency ◽

Multilevel Converters ◽

Switching Losses ◽

Light Load ◽

High Switching Frequency ◽

Operation Results ◽

Voltage Conversion

In the aerospace industry where the weight and power density are important design parameters, high frequency operation results in smaller passive components. Furthermore, to achieve a large voltage conversion ratio, which is a goal for payload systems, the use of transformers increases the size and power losses of the system. To fulfill the space and weight requirements, a transformer-less SiC-based DC-DC multilevel converter providing high voltage conversion ratios without an extremely high duty cycle has been realized. The experimental high switching frequency and low current results for a conventional, 3-level and 4-level converter utilizing Si and SiC based COTS diodes are presented. SiC-based multilevel converters show a higher efficiency due to the low reverse recovery and fast switching of the diodes, which results in a higher voltage conversion ratio. This translates to a lower duty cycle to obtain the required output voltage, whilst eliminating the need for complex filtering even under light load conditions.

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High Power Density, High-Voltage Parallel Resonant Converter Using Parasitic Capacitance on the Secondary Side of a Transformer

Electronics ◽

10.3390/electronics10141736 ◽

2021 ◽

Vol 10 (14) ◽

pp. 1736

Author(s):

Jaean Kwon ◽

Rae-Young Kim

Keyword(s):

Power Density ◽

High Voltage ◽

Electrostatic Precipitator ◽

Power Supplies ◽

Equivalent Model ◽

Resonant Converter ◽

High Voltage Power Supply ◽

Resonant Capacitor ◽

Parasitic Components ◽

Secondary Side

High-voltage DC power supplies are used in several applications, including X-ray, plasma, electrostatic precipitator, and capacitor charging. However, such a high-voltage power supply has problems, such as a decrease in reliability, owing to an increase in output ripple voltage, and a decrease in power density, owing to an increase in volume. Therefore, this study proposes a method for improving the power density of a parallel resonant converter using the parasitic capacitor of the secondary side of the transformer. Due to the fact that high-voltage power supplies have many turns on the secondary side, a significant number of parasitic capacitors are generated. In addition, in the case of a parallel resonant converter, because the transformer and the primary resonant capacitor are connected in parallel, the parasitic capacitor component generated on the secondary side of the transformer can be equalized and used. A parallel cap-less resonant converter structure developed using the parasitic components of such transformers is proposed. Primary side and secondary side equivalent model analyses are conducted in order to derive new equations and gain waveforms. Finally, the validity of the proposed structure is verified experimentally.

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AC Current Ripple in Three-Phase Four-Leg PWM Converters with Neutral Line Inductor

Energies ◽

10.3390/en14051430 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1430

Author(s):

Aleksandr Viatkin ◽

Riccardo Mandrioli ◽

Manel Hammami ◽

Mattia Ricco ◽

Gabriele Grandi

Keyword(s):

Numerical Simulations ◽

Pulse Width Modulation ◽

Neutral Line ◽

Experimental Tests ◽

Performance Comparison ◽

Design Parameters ◽

Switching Frequency ◽

Three Phase ◽

Ac Current ◽

Current Ripple

This paper presents a comprehensive study of peak-to-peak and root-mean-square (RMS) values of AC current ripples with balanced and unbalanced fundamental currents in a generic case of three-phase four-leg converters with uncoupled AC interface inductors present in all three phases and in neutral. The AC current ripple characteristics were determined for both phase and neutral currents, considering the sinusoidal pulse-width modulation (SPWM) method. The derived expressions are simple, effective, and ready for accurate AC current ripple calculations in three- or four-leg converters. This is particularly handy in the converter design process, since there is no need for heavy numerical simulations to determine an optimal set of design parameters, such as switching frequency and line inductances, based on the grid code or load restrictions in terms of AC current ripple. Particular attention has been paid to the performance comparison between the conventional three-phase three-leg converter and its four-leg counterpart, with distinct line inductance values in the neutral wire. In addition to that, a design example was performed to demonstrate the power of the derived equations. Numerical simulations and extensive experimental tests were thoroughly verified the analytical developments.

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