Designing efficient FPGA tiles for power-constrained ultra-low-power applications

High power consumption of Field-Programmable Gate Arrays (FPGAs) makes them a less attractive choice for ultra-low-power applications. Depending on the power source, ultra-low-power systems could either be constrained by power (energy harvesting systems) or by energy (battery-powered systems). In this work, we are evaluating four different FPGA tiles to find the one that is better suited for both power-constrained and energy-constrained systems. Ultra-low-power systems apply voltage downscaling to reduce the power consumption. However, the operational limits of different blocks do not allow conventional FPGA to be operated at very low voltage. Therefore, their logic capacity can only be increased by 2–4 times by applying voltage downscaling. In this work, we identified the blocks in FPGA tiles that are vulnerable at low voltage and replace them with alternate circuits. The results indicate that, by slight modifications in the conventional FPGA tiles, logic capacity can be increased up to 8 times, whereas power-delay-product can be reduced up to 74%.     

基于电压阈值的判断汽车蓄电池电量的方法

本文介绍了一种判断汽车蓄电池电量的方法。通过对汽车蓄电池电压进行监测,以电压临界值与电流变化率为指标,带以温度补偿修正,当汽车蓄电池电量过低时监测系统发出警报。该监测系统能在汽车动态时判断发动机能否正常启动,发电机能否正常工作;在汽车静态时能判断蓄电池是否正常。     

LMI‐Based Robust PID Controller Design for Voltage Control of Islanded Microgrid

This paper presents the design of a robust proportional integral derivative (PID) controller for the control of a single phase microgrid voltage. A microgrid consists of loads, distributed generation units and several power‐electronics interfaced LC filter and voltage source inverter. These loads are unknown and parameters are uncertain which produce unmodeled load dynamics. This unmodeled load dynamics reduces the voltage tracking performance of the microgrid. The proposed controller gives the robustness of the system with unmodeled load dynamics. Under different kinds of uncertainties, PID controller guarantees the stability and provides zero steady‐state error and fast transient response. The robustness and optimal performance of the controller is obtained by using linear matrix inequality approach. The performance of the controller under different uncertainties is studied. Results indicate the robustness and high voltage tracking performance of the microgrid system.     

Energy and transition-aware runtime task scheduling for multicore processors

Many embedded or portable devices have large demands on running real-time applications. The designers start to adopt the multicore processors in these devices. The multi-core processors, however, cause much higher power consumption than ever before. To resolve this problem, many researchers have focused their studies on designing the energy-aware task scheduling algorithms for multicore processors. Conventional scheduling algorithms assumed that each core can operate under different voltage levels. However, they have not considered the effects of voltage transition overheads, which may defeat the benefit of task scheduling. In this paper, we aim to resolve this scheduling problem with voltage transition overhead consideration. We formalize this problem by an integer linear programming model and propose a heuristic algorithm for a runtime environment. The experimental results show that the proposed online heuristic algorithm can obtain the comparable results with the optimal scheduling derived by the offline integer linear programming approach.     

动态闪变电压检测及电机智能自启动系统设计

为迅速准确地提取闪变电压的特征值,克服电压闪变对生产造成的损失,设计了一种智能自启动防护系统.该系统通过对闪变跌落电压实时性检测方法的分析,运用"abc-bq"变换的检测算法,检测出闪变电压波动起止时刻和有效值.同时,系统对闪变电压跌落造成的生产设备停机可以实行自动恢复或报警,为连续性生产工艺提供了一种有效的防护.     

基于IEC闪变仪测试系统的仿真研究

为了更加准确地评估风电注入电网后引起的电压波动和闪变等电能质量变化的严重程度,根据IEC闪变仪的测试原理,利用短时间闪变值Pst衡量电能质量变化.在Matlab/Simulink环境下搭建了闪变仪测量系统的模型,并对此系统及其各环节进行了设计和研究;同时,采用线性插值法计算Pst.仿真分析表明,引入增益环节后,系统低频段误差减小,可应用于风电引起的闪变测试.     

基于Linux动态频率调整的DPM方案

在嵌入式系统中,提出一个基于Linux动态频率调整(DFS)的动态电源管理(DPM)方案。该方案可以实现2个及2个以上级别的频率调整,为用户提供系统频率等级设定接口,从而增加用户自主选择功能,解决单纯依靠系统自动调整频率等级的数量限制问题,并将应用层、内核层、驱动层程序分开以增强代码可移植性。在S3C2440A平台的实验结果验证了该方案的可行性。     

Nonlinear adaptive output feedback control of series resonant DC–DC converters

The problem of regulating the output voltage of DC-to-DC series resonant converters (SRC) is addressed. The difficulty is threefold: (i) the converter model involves discontinuous and highly nonlinear terms and is controlled through a modulating frequency signal; (ii) all state variables are not accessible to measurements; (iii) the load is uncertain and may even be varying. An adaptive output feedback controller, involving online state variable estimation, is designed and shown to ensure quite satisfactory tracking performances. The controller development is performed using the adaptive backstepping control approach combined with the high-gain observer design technique.     

Nonlinear control design for excitation controller and power system stabilizer

The paper focuses on the design of excitation controller and power system stabilizer (PSS) control schemes to enhance voltage regulation and transient stability. To design the excitation controller, the nonlinear models of the synchronous generator and electrical system are suitably arranged to give an input-output nonlinear model, which is subsequently made linear by a compensating law. The PSS control scheme is designed according to a new approach, based on the inverse system theory, which guarantees satisfactory swing damping by reducing the mutual influence between transient stability and voltage regulation. The results obtained by numerical simulations in different operating conditions confirm the effectiveness of the proposed design, also in the presence of model parameter inaccuracy.