Closed-Loop Control of a Three-Port Series Resonant Converter

Multi-port DC-DC converters are a promising solution for a wide range of applications involving multiple DC sources, storage elements, and loads. Multi-active bridge (MAB) converters have attracted the interest of researchers over the past two decades due to their potential advantages such as high power density, high transfer ratio, and galvanic isolation, for example, compared to other solutions. However, the coupled power flow nature of MAB converters makes their control implementation difficult, and due to the multi-input, multi-output (MIMO) structure of their control systems, a decoupling control strategy must be designed. Various control and topology-level strategies are proposed to mitigate the coupling effect. This paper discusses the operating principles, applications, methods for analyzing power flow, advanced modulation techniques, and small signal modelling of the MAB converter. Having explained the origin of cross-coupling, the existing power flow decoupling methods are reviewed, categorized, and compared in terms of effectiveness and implementation complexity.

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“…[ 79,[114][115][116][117]124,160] [ 63,72,96,165,166] Model-free (black-box) Easy to implement. Robust to uncetenities.…”

Section: Tdamentioning

confidence: 99%

“…Ideal decoupling was the first proposed and is the most often implemented approach for the MAB converter. Using ideal decoupling, the inverse of the steady-state values of the gain matrix can be implemented in feed-forward to ideally eliminate the coupling effect, for which the decoupling terms [165] are:…”

Section: Control-level Decouplingmentioning

confidence: 99%

A Survey on Multi-Active Bridge DC-DC Converters: Power Flow Decoupling Techniques, Applications, and Challenges

et al. 2023

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“…Although such a simple control scheme is one benefit of the MSRC, the lack of energy storage in a magnetizing inductance leads to difficulty in maintaining ZVS in all load cases because the phase angle needed for the power flow may not align with the direction of the resonant current required to discharge the relevant switch parasitic output capacitance(s); which depends on the resonant tank impedance and output impedance [14]. However the control approach was expanded in [17] where the switching frequency was also varied (in a similar manner to an LLC, [18] or for a dual-active-bridge (DAB), [19], [20]) while still using phase shift control with a decoupling network to distribute power flow among the output ports. This additional freedom gives two benefits: the effective impedance of the resonant tank networks can be varied to extend the ZVS region for lower loads, and the control could continually "perturb and disturb" to find the best balance of switching and magnetic losses by ensuring that, as long as the port voltages were similar, ZVS was achieved with the smallest switching frequency possible.…”

Section: Introductionmentioning

confidence: 99%

“…power from HV to LV batteries) is also much less than the OBC's rated power [22]. Such scenarios can bring out poor performance from the switching frequency control given in [17] since it operates the MSRC partly like an LLC where low load power flow is achieved with higher switching frequencies and thus generally lower efficiency due to the risk of higher AC magnetic component losses and other switching related losses. Secondly, this poor light-load efficiency due to high switching frequency is compounded when port voltage ratios diverge from the transformer turns-ratio and thus uniform ZVS is no longer achieved.…”

Section: Introductionmentioning

confidence: 99%

“…To mitigate this effect while keeping all the advantages offered by the MSRC, this paper proposes a further augmentation of the switching-frequency and phase control from [17]. Specifically, this paper shows how super-imposing symmetrically aligned "duty cycle" modulation (later referred to as duty cycle mode) together with the phase angle and switching frequency control, can both improve light load efficiency (via reduced switching frequency and resonant currents) and widen the ZVS region for given power flow conditions (thus reducing switching losses).…”

Section: Introductionmentioning

confidence: 99%

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Increasing Light Load Efficiency in Phase-Shifted, Variable Frequency Multiport Series Resonant Converters

Langbauer,

Connaughton,

Vollmaier

et al. 2023

IEEE Access

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Multiport power conversion topologies provide the functionality of more single (and independent) converters but with just one transformer having multiple windings (i.e., ports). In automotive on-board chargers, the multiport approach combined with symmetrical series resonant circuits, the so-called multiport series resonant converter (MSRC), enable the required galvanic isolated connection from the gridside converter (i.e., usually an AC-DC power factor correction (PFC) stage) to the vehicle's batteries, i.e., the main high-voltage (HV) traction and the auxiliary low-voltage (LV), theoretically allowing to achieve increased power densities and enabling a flexible (and bidirectional) power routing among the different ports. High efficiency figures are normally specified in the considered application field for a very wide voltage ratios among the different ports, due to the variability of battery voltages, thus requiring proper and optimized control strategies of the underlying converter. The variation of the battery voltage is in fact highly affecting the MSRC operation, especially for light loads at a low state-of-charge, and high losses can be experienced since zero voltage switching conditions are lost. Beside the conventional control approach of the MSRC, where the power flow is set with a phase-shift between the individual full bridges or by changing the switching frequency, this paper proposes a novel and coordinated approach, including the manipulation of both and the additional modulation of the duty-cycle as a function of the grid-side DClink voltage (i.e., the output of the PFC stage), aiming at introducing a zero-voltage interval on the full bridge output voltages. A full mathematical description of the adopted converter topology is reported, also including accurate simulation models for losses estimation allowing a fair comparison between the proposed duty-cycle mode control and the conventional control strategy. Detailed operation guideline for achieving zero-voltage switching within the connected full bridges is also reported. Experimental results validate the proposal and highlight a significant peak and average efficiency improvements with respect to standard control approaches.INDEX TERMS multiport series resonant converter, modulation scheme, light load efficiency, DC/DC converter, battery chargers, energy and power routing, automotive converters

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Digital Closed Loop Control of a Three Port Series Resonant Converter for Electric Vehicles

Kozielski,

Mudiyanselage,

Pradhan

et al. 2024

2024 IEEE Applied Power Electronics Conference and Exposition (APEC)

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Closed-Loop Control of a Three-Port Series Resonant Converter

Cited by 6 publications

References 11 publications

A Survey on Multi-Active Bridge DC-DC Converters: Power Flow Decoupling Techniques, Applications, and Challenges

A Survey on Multi-Active Bridge DC-DC Converters: Power Flow Decoupling Techniques, Applications, and Challenges

Increasing Light Load Efficiency in Phase-Shifted, Variable Frequency Multiport Series Resonant Converters

Digital Closed Loop Control of a Three Port Series Resonant Converter for Electric Vehicles

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