Full Digital Control and Multi-Loop Tuning of a Three-Level T-Type Rectifier for Electric Vehicle Ultra-Fast Battery Chargers
The rapid development of electric vehicle ultra-fast battery chargers is increasingly demanding higher efficiency and power density. In particular, a proper control of the grid-connected active front–end can ensure minimum passive component size (i.e., limiting design oversizing) and reduce the over...
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doaj-cbf941136f4941e7b668c0f7d9ad32b92021-07-01T00:27:16ZengMDPI AGElectronics2079-92922021-06-01101453145310.3390/electronics10121453Full Digital Control and Multi-Loop Tuning of a Three-Level T-Type Rectifier for Electric Vehicle Ultra-Fast Battery ChargersDavide Cittanti0Matteo Gregorio1Eugenio Bossotto2Fabio Mandrile3Radu Bojoi4Energy Department “Galileo Ferraris”, Politecnico di Torino, 10129 Torino, ItalyEnergy Department “Galileo Ferraris”, Politecnico di Torino, 10129 Torino, ItalyEnergy Department “Galileo Ferraris”, Politecnico di Torino, 10129 Torino, ItalyEnergy Department “Galileo Ferraris”, Politecnico di Torino, 10129 Torino, ItalyEnergy Department “Galileo Ferraris”, Politecnico di Torino, 10129 Torino, ItalyThe rapid development of electric vehicle ultra-fast battery chargers is increasingly demanding higher efficiency and power density. In particular, a proper control of the grid-connected active front–end can ensure minimum passive component size (i.e., limiting design oversizing) and reduce the overall converter losses. Moreover, fast control dynamics and strong disturbance rejection capability are often required by the subsequent DC/DC stage, which may act as a fast-varying and/or unbalanced load. Therefore, this paper proposes the design, tuning and implementation of a complete digital multi-loop control strategy for a three-level unidirectional T-type rectifier, intended for EV ultra-fast battery charging. First, an overview of the operational basics of three-level rectifiers is presented and the state-space model of the considered system is derived. A detailed analysis of the mid-point current generation process is also provided, as this aspect is widely overlooked in the literature. In particular, the converter operation under unbalanced split DC-link loads is analyzed and the converter mid-point current limits are analytically identified. Four controllers (i.e., dq-currents, DC-link voltage and DC-link mid-point voltage balancing loops) are designed and their tuning is described step-by-step, taking into account the delays and the discretization introduced by the digital control implementation. Finally, the proposed multi-loop controller design procedure is validated on a 30 kW, 20 kHz T-type rectifier prototype. The control strategy is implemented on a single general purpose microcontroller unit and the performances of all control loops are successfully verified experimentally, simultaneously achieving low input current zero-crossing distortion, high step response and disturbance rejection dynamics, and stable steady-state operation under unbalanced split DC-link loading.https://www.mdpi.com/2079-9292/10/12/1453digital controlgrid-connected convertersthree-level T-type rectifierVIENNA rectifieractive front-endpower factor corrector |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Davide Cittanti Matteo Gregorio Eugenio Bossotto Fabio Mandrile Radu Bojoi |
spellingShingle |
Davide Cittanti Matteo Gregorio Eugenio Bossotto Fabio Mandrile Radu Bojoi Full Digital Control and Multi-Loop Tuning of a Three-Level T-Type Rectifier for Electric Vehicle Ultra-Fast Battery Chargers Electronics digital control grid-connected converters three-level T-type rectifier VIENNA rectifier active front-end power factor corrector |
author_facet |
Davide Cittanti Matteo Gregorio Eugenio Bossotto Fabio Mandrile Radu Bojoi |
author_sort |
Davide Cittanti |
title |
Full Digital Control and Multi-Loop Tuning of a Three-Level T-Type Rectifier for Electric Vehicle Ultra-Fast Battery Chargers |
title_short |
Full Digital Control and Multi-Loop Tuning of a Three-Level T-Type Rectifier for Electric Vehicle Ultra-Fast Battery Chargers |
title_full |
Full Digital Control and Multi-Loop Tuning of a Three-Level T-Type Rectifier for Electric Vehicle Ultra-Fast Battery Chargers |
title_fullStr |
Full Digital Control and Multi-Loop Tuning of a Three-Level T-Type Rectifier for Electric Vehicle Ultra-Fast Battery Chargers |
title_full_unstemmed |
Full Digital Control and Multi-Loop Tuning of a Three-Level T-Type Rectifier for Electric Vehicle Ultra-Fast Battery Chargers |
title_sort |
full digital control and multi-loop tuning of a three-level t-type rectifier for electric vehicle ultra-fast battery chargers |
publisher |
MDPI AG |
series |
Electronics |
issn |
2079-9292 |
publishDate |
2021-06-01 |
description |
The rapid development of electric vehicle ultra-fast battery chargers is increasingly demanding higher efficiency and power density. In particular, a proper control of the grid-connected active front–end can ensure minimum passive component size (i.e., limiting design oversizing) and reduce the overall converter losses. Moreover, fast control dynamics and strong disturbance rejection capability are often required by the subsequent DC/DC stage, which may act as a fast-varying and/or unbalanced load. Therefore, this paper proposes the design, tuning and implementation of a complete digital multi-loop control strategy for a three-level unidirectional T-type rectifier, intended for EV ultra-fast battery charging. First, an overview of the operational basics of three-level rectifiers is presented and the state-space model of the considered system is derived. A detailed analysis of the mid-point current generation process is also provided, as this aspect is widely overlooked in the literature. In particular, the converter operation under unbalanced split DC-link loads is analyzed and the converter mid-point current limits are analytically identified. Four controllers (i.e., dq-currents, DC-link voltage and DC-link mid-point voltage balancing loops) are designed and their tuning is described step-by-step, taking into account the delays and the discretization introduced by the digital control implementation. Finally, the proposed multi-loop controller design procedure is validated on a 30 kW, 20 kHz T-type rectifier prototype. The control strategy is implemented on a single general purpose microcontroller unit and the performances of all control loops are successfully verified experimentally, simultaneously achieving low input current zero-crossing distortion, high step response and disturbance rejection dynamics, and stable steady-state operation under unbalanced split DC-link loading. |
topic |
digital control grid-connected converters three-level T-type rectifier VIENNA rectifier active front-end power factor corrector |
url |
https://www.mdpi.com/2079-9292/10/12/1453 |
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