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| Main Authors: | , , |
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| Format: | Preprint |
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2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2507.10086 |
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| _version_ | 1866908503183982592 |
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| author | Qian, Guanyu Yan, Haoxian Cui, Xiaofan |
| author_facet | Qian, Guanyu Yan, Haoxian Cui, Xiaofan |
| contents | Fast-response voltage regulation is essential for data-center Voltage Regulation Modules (VRMs) powering Artificial Intelligence (AI) workloads, which exhibit both small-amplitude fluctuations and abrupt full-load steps. This paper introduces a control scheme that integrates a linear controller and a nonlinear controller for variable-frequency Series-Capacitor Buck (SCB) converters. First, an accurate small-signal model is derived via a Switching-Synchronized Sampled State-Space (5S) framework, yielding discrete-time transfer functions and root-locus insights for direct digital design. A critical concern for SCB converters is series-capacitor oscillation during heavy load steps if the strict switching sequence is not maintained. To accelerate large-signal transients, a time-optimal control strategy based on Pontryagins Maximum Principle (PMP) relaxes the switching constraints to compute time-optimal switching sequences. A transition logic is then proposed to integrate the high-bandwidth small-signal controller and the large-signal controller. Simulations demonstrate a rapid output voltage recovery under a heavy load step-up, over ten times faster than a linear controller-only design. Preliminary hardware tests indicate a stable rejection to heavy load disturbances with zero steady-state error. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_10086 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Fast-Response Variable-Frequency Series-Capacitor Buck VRM Through Integrated Control Approaches Qian, Guanyu Yan, Haoxian Cui, Xiaofan Applied Physics Systems and Control Fast-response voltage regulation is essential for data-center Voltage Regulation Modules (VRMs) powering Artificial Intelligence (AI) workloads, which exhibit both small-amplitude fluctuations and abrupt full-load steps. This paper introduces a control scheme that integrates a linear controller and a nonlinear controller for variable-frequency Series-Capacitor Buck (SCB) converters. First, an accurate small-signal model is derived via a Switching-Synchronized Sampled State-Space (5S) framework, yielding discrete-time transfer functions and root-locus insights for direct digital design. A critical concern for SCB converters is series-capacitor oscillation during heavy load steps if the strict switching sequence is not maintained. To accelerate large-signal transients, a time-optimal control strategy based on Pontryagins Maximum Principle (PMP) relaxes the switching constraints to compute time-optimal switching sequences. A transition logic is then proposed to integrate the high-bandwidth small-signal controller and the large-signal controller. Simulations demonstrate a rapid output voltage recovery under a heavy load step-up, over ten times faster than a linear controller-only design. Preliminary hardware tests indicate a stable rejection to heavy load disturbances with zero steady-state error. |
| title | Fast-Response Variable-Frequency Series-Capacitor Buck VRM Through Integrated Control Approaches |
| topic | Applied Physics Systems and Control |
| url | https://arxiv.org/abs/2507.10086 |