2026-09-24T22:23:18Zhttps://researchcommons.waikato.ac.nz/server/oai/request

oai:researchcommons.waikato.ac.nz:10289/106242017-12-08T00:47:49Zcom_10289_2222col_10289_2223

Supercapacitor-based linear converter for voltage regulator modules Wickramasinghe, Thilini Chintha Prabha Kumari Kularatna, Nihal Steyn-Ross, D. Alistair This thesis investigates a linear converter technique suitable for microprocessor voltage regulator modules (VRMs). The original linear regulator is the patented supercapacitor assisted low-dropout regulator (SCALDO). A less complex, lower cost design was achieved by reducing the number of switches in the original SCALDO and adding a second low dropout regulator (LDO). In the initial implementation of this reduced-switch SCALDO (RS-SCALDO), output regulation failed due to the presence of a parasitic body-diode in standard LDOs. The body-diode forms an unwanted discharge path to ground for the supercapacitor. In order to block this path, an application specific LDO that operates in the third quadrant of a MOSFET current-vs-voltage transfer function was investigated. A 3.5-to-1.5 V RS-SCALDO was designed with a supercapacitor, two LDOs and two switches. Compared with the standard SCALDO approach, this new design halves the number of switches required. Discrete MOSFET-based high-current LDOs were developed and combined with a common feedback control circuit. Voltage identification (VID) capability was implemented using a digital potentiometer. Theoretically, when an LDO converts 3.5 V to 1.5 V a maximum efficiency of 1.5/3.5(~43%) can be achieved. According to the general theory of SCALDO, a single supercapacitor configuration can achieve nearly twice the linear regulator efficiency. The 3.5-to-1.5 V, 5 A RS-SCALDO achieved an approximate end-to-end efficiency of 80%, thus, agreeing with SCALDO general theory. Large-signal analysis was used to model MOSFET non-linearities and predict the performance of LDOs, switches and the overall system. Matlab modeling predictions for body-diode behaviour were cross-checked via SPICE simulation; the results agreed with bench measurements. RS-SCALDO regulators cycle at very low frequencies, usually in the range of millihertz to hertz. Therefore, electromagnetic interference emitted by high-frequency switched-mode VRMs is not an issue here. Compared to typical high-frequency VRMs, RS-SCALDO topology provides similar efficiencies with the high slew-rate and low noise output of a linear regulator. In generalized SCALDO configuration with n supercapacitors, a total of 3n+1 switches required; in contrast RS-SCALDO reduces the switch count to 2n. With the elimination of the body-diode parasitics, the technique can be extended to much higher currents. University of Waikato 2016 Thesis en https://hdl.handle.net/10289/10624 https://researchcommons.waikato.ac.nz/bitstreams/df2acd36-789c-4a86-8d6f-7ad15e6b24ff/download d344a13f2823cbf3b75c225b01fb8a2b https://researchcommons.waikato.ac.nz/bitstreams/518c78f3-1834-4399-afe3-4b65978b1003/download 54ddfaae9e939fb9fe062bd0161afbd5 https://researchcommons.waikato.ac.nz/bitstreams/b9988c89-46d3-4664-8fc5-9cf04fd303bb/download 02e0847522c281a42c0c038573fdcebb All items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated. DC-DC converter Efficiency Supercapacitors