Analysis and Validation of Variable Transformers

Suarez, Camilo; Cobaleda, Diego Bernal; Martínez, Wilmar

doi:10.1109/isie45552.2021.9576416

Cited by 5 publications

(8 citation statements)

References 15 publications

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“…As there is no information in the literature that relates a VT with a Dual-Active-Bridge (DAB), in this paper the model proposed by the authors in [10] is modified and implemented using the small signal model of the DAB proposed in [11]. In this application the VT is intended to improve the efficiency of a DAB converter working in a wide range of voltages and loads, as it contributes to compensating the output voltage variations by modifying the converter's transformer equivalent turns ratio keeping a soft switching operation.…”

Section: Fig 1: Gyrator Capacitor Representationmentioning

confidence: 99%

“…3b is presented next, the equations are shown in TABLE I. The model is proposed in [11] and is used to determine the Leakage inductance L lk , the magnetizing inductance L mag and the equivalent turns ratio n eq according to the variations on the control variable reluctance ℜ v .…”

Section: B Dual Active Bridge Soft Switching Regionmentioning

confidence: 99%

“…Inductances L ℜ1 , L ℜ2 , L ℜv are related to the previous mentioned permances P 1 , P 2 , Γ o respectively, as the model in [11] is reflected to the primary side, the permeances needs to be multiplied by the second power of the number of turns in the primary winding n 2 p P i =L ℜi . With the variations shown in Fig.…”

Section: B Dual Active Bridge Soft Switching Regionmentioning

confidence: 99%

“…5b and the small signal model, the oscillations due to non-orthogonal fluxes coming from the primary and secondary winding, vary from 160µ[H] -130µ[H] which is translated to 0.15µ[H * turns] -0.12µ[H * turns] According to these values, the n eq is around 2.5, and the variations in the permeance ∆Γ = 20%. TABLE I: Transformer small-signal-model according to [11]…”

Section: B Dual Active Bridge Soft Switching Regionmentioning

confidence: 99%

“…As mentioned before, authors in [11] propose a small signal model of a variable transformer. This model is tested using a Dual Active Bridge converter, as the voltages in these type of application depends mainly on Battery levels, the dynamic of the system is considerably slower than the ferrite dynamic response.…”

Section: Linearization and Control Designmentioning

confidence: 99%

See 4 more Smart Citations

Linear Control Compensator for a Variable-Transformer in Wide-Voltage Power Converters

Cobaleda

Tian

Suarez

et al. 2022

2022 IEEE 31st International Symposium on Industrial Electronics (ISIE)

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This work presents the design and simulation of a controllable magnetic device. The device can help the Dual Active Bridge converter (DAB) to operate in the soft switching region for wide-load applications. The control law is based on the modification of the ferrite-core's permeance for Variable-Transformers (VT). The frecuency-domain's model of the VT control leg is obtained using the Gyrator-Capacitor theory. Finally, this model is found by the premise that the interactions of the transformer's main fluxes are minimum in the control leg, furthermore this paper also proposed a ferrite-core construction that reduces these interactions, therefore the induced voltage in the control winding is also minimized, meaning the parallel interactions of the fluxes are reduced. The results shows that the perturbations are manageable for the control scheme and do not affect the device operation.

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Section: Fig 1: Gyrator Capacitor Representationmentioning

confidence: 99%

Section: B Dual Active Bridge Soft Switching Regionmentioning

confidence: 99%

Section: B Dual Active Bridge Soft Switching Regionmentioning

confidence: 99%

Section: B Dual Active Bridge Soft Switching Regionmentioning

confidence: 99%

Section: Linearization and Control Designmentioning

confidence: 99%

See 3 more Smart Citations

Linear Control Compensator for a Variable-Transformer in Wide-Voltage Power Converters

Cobaleda

Tian

Suarez

et al. 2022

2022 IEEE 31st International Symposium on Industrial Electronics (ISIE)

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Analysis of Wide Voltage Variation in LLC Converters Using Variable Transformers

et al. 2022

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Magnetically Controlled Transformer With Variable Turns Ratio and Low Series Inductance: Analysis and Implementation Toward Its Application in SMPS

Buitrago,

Cobaleda,

Martinez

2023

IEEE Trans. Power Electron.

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A comprehensive description of magnetically controlled transformers is presented in this paper to asses their potential in isolated and resonant power converters. These converters benefit from implementing variable magnetics as the soft switching zones and voltage operating ranges are extended, along with fixed or quasi-fixed frequency operation. To represent the variation of the transformer's equivalent turns ratio and parallel-series inductance, the cantilever model is selected. Moreover, two novel transformer structures employing parallel pre-magnetization are introduced; only off-the-shelf magnetic cores are required for their implementation. In conjunction with small signal analytical expressions, an adapted SPICE model is provided and compared to FEA simulations. Additionally, the impact of the stray inductance of the structures is assessed, improving the understanding of this controllable magnetic device's constraints and trade-offs. Experimental results align with the derived models and prove the proposed structures to provide significant variations in transformer equivalent turns ratio, keeping a relatively high parallel-series inductance ratio.

show abstract

Analysis and Validation of Variable Transformers

Cited by 5 publications

References 15 publications

Linear Control Compensator for a Variable-Transformer in Wide-Voltage Power Converters

Linear Control Compensator for a Variable-Transformer in Wide-Voltage Power Converters

Analysis of Wide Voltage Variation in LLC Converters Using Variable Transformers

Magnetically Controlled Transformer With Variable Turns Ratio and Low Series Inductance: Analysis and Implementation Toward Its Application in SMPS

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