Power Management Subsystem Research Articles

Ultrasonic wireless power links for battery-free condition monitoring in metallic enclosures

This paper presented a novel ultrasonic wireless power link (UWPL) to provide power supply for embedded condition monitoring of enclosed metallic structures, where recharging or replacing batteries can be problematic. Two piezoelectric transducers are adopted to establish the wireless power links, within which one transducer is used to generate ultrasonic waves and the other is to receive the transferred ultrasonic energy and to energize the associated embedded condition monitoring units. A power management solution is established to regulate the receiver output into a constant voltage suitable for sensing application. A theoretical model was established to understand the UWPL dynamics and to analyze the energy budget balance between the UWPL and the sensing power demands. A finite element model was built to validate the proposed idea. The UWPL was then experimentally implemented using two piezoelectric transducers and tested in aluminium plates with different thickness. A power management sub-system was developed and tested for sensing applications. An output power of 1.73 mW was obtained on a 1.5 kΩ resister with the input voltage of 15 V at 42.6 kHz through a 6 mm-thick aluminium plate. Sufficient power can be transferred over a large distance via metallic structures, showing the capability in implementing battery-free condition monitoring of enclosed metallic structures, such as petroleum pipelines, engines, and aluminium airframe.

Marvell ThunderX3: Next-Generation Arm-Based Server Processor

Marvell ThunderX3 is the third-generation Arm-based server processor from Marvell. This article describes the architecture of ThunderX3, going into details of core microarchitecture. ThunderX3 is distinctive among mainstream processors in supporting four SMT threads. The article describes the threading microarchitecture of ThunderX3 and highlights threading benefits. The article also touches on the on-chip interconnect and L3-cache and the power management subsystem. Initial benchmark results from silicon show 30%+ single thread and up to 3X socket level performance gains over the prior generation resulting in industry-leading single thread and socket level performance.

A 130-nm Ferroelectric Nonvolatile System-on-Chip With Direct Peripheral Restore Architecture for Transient Computing System

Owing to its unique capability to sustain computation progress over power outages, a nonvolatile processor (NVP) is promising for energy-harvesting-powered Internet-of-Things devices. However, the widespread application of NVP is continually blocked by the system integration issues and the configuration overheads of peripheral devices. This paper presents a nonvolatile system-on-chip (NVSoC) with improved integration level, power management flexibility, and system wake-up speed. An on-chip power management subsystem is designed to minimize the number of external components while supporting versatile power policies. And a direct peripheral restore architecture is outlined, which enables a fast and parallel re-configuration of peripheral devices after the resumption of power supply. A test chip is fabricated in a 130-nm ferroelectric-CMOS process with 22.09-mm2 area. Measurement results show 6 $\times $ higher data throughput as compared with a conventional NVP when facing power failures.

A Self-Powered System for Large-Scale Strain Sensing by Combining CMOS ICs With Large-Area Electronics

We present a 2nd-generation system for high-resolution structural-health monitoring of bridges and buildings. The system combines large-area electronics (LAE) and CMOS ICs via scalable interfaces based on inductive and capacitive coupling. This enables architectures where the functional strengths of both technologies can be leveraged to enable large-scale strain sensing scalable to cm resolution yet over large-area sheets. The system consists of three subsystems: (1) a power-management subsystem, where LAE is leveraged for solar-power harvesting, and CMOS is leveraged for power conversion and regulation; (2) a sensing subsystem, where LAE is leveraged for dense strain sensing, and CMOS is leveraged for multi-sensor acquisition; and (3) a communication subsystem, where LAE is leveraged for long-range interconnects, and CMOS is leveraged for low-power transceivers. The power-management subsystem achieves 30% efficiency for DC-AC power inversion and inductive power delivery to the CMOS IC and 80.5% overall efficiency for generating three voltages via DC-DC converters. The sensing subsystem has a readout noise level of 23 μStrainRMS (141 μStrainRMS including sensor noise), at an energy/meas. of 148 nJ and 286 nJ for readout and sensor-accessing control, respectively. The communication subsystem achieves an energy/bit of 14.6 pJ/4.3 pJ (Tx/Rx) at a distance of 7.5 m and a data rate of 2 Mb/s.

Performance evaluation of a polymer electrolyte membrane fuel cell system for powering portable freezer

A polymer electrolyte membrane fuel cell (PEMFC) powered portable freezer has been developed. The PEMFC system is composed of an air-cooled fuel cell stack module with combined oxidant and coolant flow, a fuel supply subsystem with two metal hydride canisters, a power management subsystem with a DC–DC converter and a lead acid battery, and a control electronics subsystem. The vapor compression refrigeration cycle has been adopted for refrigerating. The control logic for fuel cell stack operation, cabinet temperature maintenance and fuel canister replacement has been designed for a stable system operation. To estimate PEMFC system performance, the stack power output, parasitic loss and battery charging power are measured for various external loads. The PEMFC system provides a rated power output of 200.5W at 13.4V with balance-of-plant (BOP) efficiency of 72%. The maximum system efficiency based on lower heating value (LHV) is 37% at 120.7W. The PEMFC powered freezer stably operates with the continuous replacement of hydrogen canisters, and the cabinet temperature drops to −21.8°C when the ambient temperature is 26.6°C.

A 65 nm 32 b Subthreshold Processor With 9T Multi-Vt SRAM and Adaptive Supply Voltage Control

An energy-efficient SoC with 32 b subthreshold RISC processor cores, 32 kB conventional cache memory, and 9T ultra-low voltage (ULV) SRAM based on a flexible and extensible architecture was fabricated on a 2.7 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> test chip in 65 nm low power CMOS. The processor cores are based on a custom standard cell library that was designed using a multiobjective approach to optimize noise margins, switching energy, and propagation delay simultaneously. The cores operate over a supply voltage range from 200 mV (best samples) to 1.2 V with clock frequencies from 10 kHz to 94 MHz at room temperature. The lowest energy consumption per cycle of 9.94 pJ is observed at 325 mV and 133 kHz. A 2 kb ULV SRAM macro achieves minimum energy per operation at averages of 321 mV (0.030 σ/μ), 567 fJ (0.037 σ/μ), and 730 kHz (0.184 σ/μ), for equal number of 32 b read/write operations. The off-chip performance and power management subsystem provides dynamic voltage and frequency scaling (DVFS) combined with an adaptive supply voltage generation for dynamic PVT compensation.

Optimization design of the stratospheric airship’s power system based on the methodology of orthogonal experiment

The optimization design of the power system is essential for stratospheric airships with paradoxical requirements of high reliability and low weight. The methodology of orthogonal experiment is presented to deal with the problem of the optimi- zation design of the airship's power system. Mathematical models of the solar array, regenerative fuel cell, and power management subsystem (PMS) are presented. The basic theory of the method of orthogonal experiment is discussed, and the selection of factors and levels of the experiment and the choice of the evaluation function are also revealed. The proposed methodology is validated in the optimization design of the power system of the ZhiYuan-2 stratospheric airship. Results show that the optimal configuration is easily obtained through this methodology. Furthermore, the optimal configuration and three sub-optimal configurations are in the Pareto frontier of the design space. Sensitivity analyses for the weight and reliability of the airship's power system are presented.

Development of Proton Exchange Membrane Fuel Cell System for Portable Refrigerator

A proton exchange membrane (PEM) fuel cell system for powering a portable refrigerator is developed. The PEM fuel cell system consists of an air-cooled stack with combined oxidant and coolant flow, a hydrogen supply subsystem with two metal hydride canisters, a power management subsystem with a DC-DC converter and a rechargeable battery, and a control electronics subsystem. To analyze the performance of the PEM fuel cell system, the stack power output, the balance-of-plant (BOP) power consumption and the battery charging power are measured at various external loading conditions. The BOP system shows low efficiency of 20.7% under no-load condition, while it increases to 72.3% at 200.5 W system power output.

200 W급 휴대용 고분자 전해질막 연료전지 시스템 개발

A 200 W portable polymer electrolyte membrane fuel cell (PEMFC) system is developed. The PEMFC system consists of an air-cooled fuel cell stack module, a fuel supply subsystem, a power management subsystem, and a control electronics subsystem. The control logic is designed for the stable system operation. The system-level performance evaluation discloses that the present PEMFC system provides a rated power output of 200.5 W at 13.4 V with the maximum balance-of-plant (BOP) efficiency of 72%, and maximum system efficiency based on lower heating value (LHV) is 37% at 120.7 W system power output.

A ZigBee multi-powered wireless acquisition device for remote sensing applications in precision viticulture

This paper is part of a long-term effort to introduce precision viticulture in the region of Demarcated Region of Douro. It presents the architecture, hardware and software of a platform designed for that purpose, called MPWiNodeZ. A major feature of this platform is its power-management subsystem, able to recharge batteries with energy harvested from the surrounding environment from up to three sources. It allows the system to sustain operation as a general-purpose wireless acquisition device for remote sensing in large coverage areas, where the power to run the devices is always a concern. The MPWiNodeZ, as a ZigBee™ network element, provides a mesh-type array of acquisition devices ready for deployment in vineyards. In addition to describing the overall architecture, hardware and software of the monitoring system, the paper also reports on the performance of the module in the field, emphasising the energy issues, crucial to obtain self-sustained operation. The testing was done in two stages: the first in the laboratory, to validate the power management and networking solutions under particularly severe conditions, the second stage in a vineyard. The measurements about the behaviour of the system confirm that the hardware and software solutions proposed do indeed lead to good performance. The platform is currently being used as a simple and compact yet powerful building block for generic remote sensing applications, with characteristics that are well suited to precision viticulture in the DRD region. It is planned to be used as a network of wireless sensors on the canopy of vines, to assist in the development of grapevine powdery mildew prediction models.

Photovoltaic, Gravitationally Stabilized, Solid-State Satellite Solar Power Station

The salient feature of a gravitationally-stabilized satellite solar power system (SSPS) for a photovoltaic system is that the large solar array is separated into smaller segments or subunits, joined together in a linear array oriented along the local vertical. Applicability of gravitational stabilization to the design of photovoltaic SSPS is demonstrated. Both actively controlled systems using multiple solar panels oriented to the sun and passively controlled systems requiring no sun orientation are considered and determined to be feasible. Expressions for gravity-gradient induced tension and restoring torques about the local vertical are assessed. Particular attention is directed to the applicability of solid-state approaches to the design of SSPS. It is shown that an all solid-state SSPS utilizing the LITOMIC (light-to-microwave conversion) concept is feasible but that a hybrid system employing a combination of both solid-state and cryogenic cooled low-voltage techniques to the design of the power management and distribution subsystem may also provide a solution.