A new design for an ultra-low power, low phase noise differential 10 GHz LC voltage-controlled oscillator (VCO) which is biased in the subthreshold regime, is presented in the 0.18 μm CMOS process, for the first time...A new design for an ultra-low power, low phase noise differential 10 GHz LC voltage-controlled oscillator (VCO) which is biased in the subthreshold regime, is presented in the 0.18 μm CMOS process, for the first time. The designed circuit topology is an NMOS only cross-coupled LC-tank VCO which has an extra symmetric centre tapped inductor between the source ends of the cross-coupled transistors. Using this inductor leads to an improvement of the phase noise of VCO about 3.5 dB. At the supply voltage of 0.46 V, the output phase noise is -107.8 dBc/Hz at 1 MHz offset frequency from the carrier frequency of 10.53 GHz, so that the dc power consumption is only 0.346 mW. Tuning range is between 10.53 GHz to 11.35 GHz which is 7.5% and the figure of merit is -193.8 dB, which this result shows that this is the first VCO design in the subthreshold regime at this frequency. This VCO can be used for multi-standard wireless LAN communication protocols 802.11a/b/g easily by a frequency division of 2 or 4 respectively.展开更多
Modern fault-resilient microgrids(MGs)require the operation of healthy phases during unbalanced short-circuits to improve the system reliability.This study proposes a differential power based selective phase tripping ...Modern fault-resilient microgrids(MGs)require the operation of healthy phases during unbalanced short-circuits to improve the system reliability.This study proposes a differential power based selective phase tripping scheme for MGs consisting of synchronous and inverter-interfaced distributed generators(DGs).First,the differential power is computed using the line-end superimposed voltage and current signals.Subsequently,to make the scheme threshold-free,a power coefficient index is derived and used for identifying faulted phases in an MG.The protection scheme is tested on a standard MG operating in either grid-connected or islanding mode,which is simulated using PSCAD/EMTDC.The efficacy of the scheme is also assessed on the OPAL-RT manufactured real-time digital simulation(RTDS)platform.Further,the performance of the proposed protection scheme is compared with a few existing methods.The results show that the selective tripping of faulted phases in MGs can be achieved quickly and securely using the proposed scheme.展开更多
有源电力滤波器(active power filter,APF)由于其突出性能已被证明是谐波抑制的有效手段之一,然而APF主电路为电压源逆变器(voltage source inverter,VSI),是一个非线性多变量、强耦合的系统,难以建立精确的数学模型,从而给控制器设计...有源电力滤波器(active power filter,APF)由于其突出性能已被证明是谐波抑制的有效手段之一,然而APF主电路为电压源逆变器(voltage source inverter,VSI),是一个非线性多变量、强耦合的系统,难以建立精确的数学模型,从而给控制器设计及应用带来困难。该文基于微分几何理论提出一种状态反馈精确线性化方法,推导出非线性坐标映射以及非线性反馈变换方程,将APF系统精确线性化,最终实现三相并联电压型APF有功、无功解耦控制器的设计。最后使用Matlab进行仿真并基于DSP和FPGA构成的双微处理器结构设计控制器进行了实验,仿真及实验结果表明,该控制策略能较好的实现APF的解耦控制,具有较好的补偿特性,经该控制算法补偿,谐波畸变率限制在2%以下,同时给出数字PI控制的实验结果作为比较。展开更多
文摘A new design for an ultra-low power, low phase noise differential 10 GHz LC voltage-controlled oscillator (VCO) which is biased in the subthreshold regime, is presented in the 0.18 μm CMOS process, for the first time. The designed circuit topology is an NMOS only cross-coupled LC-tank VCO which has an extra symmetric centre tapped inductor between the source ends of the cross-coupled transistors. Using this inductor leads to an improvement of the phase noise of VCO about 3.5 dB. At the supply voltage of 0.46 V, the output phase noise is -107.8 dBc/Hz at 1 MHz offset frequency from the carrier frequency of 10.53 GHz, so that the dc power consumption is only 0.346 mW. Tuning range is between 10.53 GHz to 11.35 GHz which is 7.5% and the figure of merit is -193.8 dB, which this result shows that this is the first VCO design in the subthreshold regime at this frequency. This VCO can be used for multi-standard wireless LAN communication protocols 802.11a/b/g easily by a frequency division of 2 or 4 respectively.
文摘Modern fault-resilient microgrids(MGs)require the operation of healthy phases during unbalanced short-circuits to improve the system reliability.This study proposes a differential power based selective phase tripping scheme for MGs consisting of synchronous and inverter-interfaced distributed generators(DGs).First,the differential power is computed using the line-end superimposed voltage and current signals.Subsequently,to make the scheme threshold-free,a power coefficient index is derived and used for identifying faulted phases in an MG.The protection scheme is tested on a standard MG operating in either grid-connected or islanding mode,which is simulated using PSCAD/EMTDC.The efficacy of the scheme is also assessed on the OPAL-RT manufactured real-time digital simulation(RTDS)platform.Further,the performance of the proposed protection scheme is compared with a few existing methods.The results show that the selective tripping of faulted phases in MGs can be achieved quickly and securely using the proposed scheme.
文摘有源电力滤波器(active power filter,APF)由于其突出性能已被证明是谐波抑制的有效手段之一,然而APF主电路为电压源逆变器(voltage source inverter,VSI),是一个非线性多变量、强耦合的系统,难以建立精确的数学模型,从而给控制器设计及应用带来困难。该文基于微分几何理论提出一种状态反馈精确线性化方法,推导出非线性坐标映射以及非线性反馈变换方程,将APF系统精确线性化,最终实现三相并联电压型APF有功、无功解耦控制器的设计。最后使用Matlab进行仿真并基于DSP和FPGA构成的双微处理器结构设计控制器进行了实验,仿真及实验结果表明,该控制策略能较好的实现APF的解耦控制,具有较好的补偿特性,经该控制算法补偿,谐波畸变率限制在2%以下,同时给出数字PI控制的实验结果作为比较。
