Chip design of a 5.8-GHz fractional-N frequency synthesizer with a tunable G_m-C loop filter

This paper proposes a novel Gm-C loop filter instead of a conventional passive loop filter used in a phase-locked loop. The innovative advantage of the proposed architecture is tunable loop filter bandwidth and hence the process variations of passive elements of resistance R and capacitance C can be overcome and the chip area is greatly reduced. Furthermore, the MASH 1-1-1 sigma-delta （ZA） modulator is adopted for performing the fractional division number and hence improves the phase noise as well. Measured results show that the locked phase noise is -114.1 dBc/Hz with lower Gm-C bandwidth and -111.7 dBm/C with higher Gm-C bandwidth at 1 MHz offset from carrier of 5.68 GHz. Including pads and built-in Gm-C filter, the chip area of the proposed frequency synthesizer is 1.06 mm2. The output power is -8.69 dBm at 5.68 CHz and consumes 56 mW with an off-chip buffer from 1.8-V supply voltage.

An area-saving dual-path loop filter for low-voltage integrated phase-locked loops

This paper proposes an area-saving dual-path loop filter（LPF）for low-voltage integrated phase-locked loops（PLLs）.With this LPF,output current of the lowpass-path charge-pump（CP）is B times（B〉1）as great as that of the integration-path CP.By adding voltages across these two paths,the zero-capacitance is magnified B times equivalently.As a result,the chip size is greatly reduced.Based on this LPF,a 1.2 V 3.5 GHz-band PLL is fabricated in SMIC 0.18μm RFCMOS technology.Its zero-capacitance is only 1/30 of that in conventional second-order LPFs. Measured data show that,at a frequency of 3.20 GHz,phase noise is–120.2 dBc/Hz at 1 MHz offset,reference spur is–72 dBc,and power is 24 mW.

A phase-locked loop using ESO-based loop filter for grid-connected converter: performance analysis

An extended state observer(ESO)-based loop filter is designed for the phase-locked loop(PLL)involved in a disturbed grid-connected converter(GeC).This ESO-based design enhances the performances and robustness of the PLL,and,therefore,improves control performances of the disturbed GeCs.Besides,the ESO-based LF can be applied to PLLs with extra filters for abnormal grid conditions.The unbalanced grid is particularly taken into account for the performance analysis.A tuning approach based on the well-designed PI controller is discussed,which results in a fair comparison with conventional PI-type PLLs.The frequency domain properies are quantitatively analysed with respeet to the control stability and the noises rejection.The frequency domain analysis and simulation results suggesti that the performances of the generated ESO-based controllers are comparable to those of the PI control at low frequency,while have better ability to atenuate high-frequency measurement noises.The phase margin decreases slightly,but remains acceptable.Finally,experimental tests are conducted with a hybrid power hardwarein-the-loop benchmark,in which balanced/unbalanced cases are both explored.The obtained results prove the effectiveness of ESO based PLLs when applied to the disturbed GeC.

Wavelength-Tunable Single Frequency Ytterbium-Doped Fiber Laser with Loop Mirror Filter

By using a loop mirror filter, a novel wavelength-tunable single-frequency ytterbium-doped fiber laser is developed to select single longitudinal modes in a linear cavity. The output wavelength could be tuned 2.4 nm intervals range from 1063.3 to 1065.Tnrn with the temperature change of the fiber Bragg grating. The maximum output power could reach 32 m W while the pump power increases to 120 m W. The corresponding optical-to-optical conversion efficiency is 26.7% and the slope efficiency is 33.9%, respectively. The output power fluctuation is below 2%, and its highest signal-to-noise ratio is 60 dB.

Tunable Single-Passband Microwave Photonic Filter Based on Sagnac Loop and Fabry-Perot Laser Diode

A tunable single-passband microwave photonic filter is proposed and demonstrated, based on a laser diode (LD) array with multiple optical carriers and a Fabry-Perot (F-P) laser diode. Multiple optical carriers in conjunction with the F-P LD will realize a filter with multiple passbands. By adjusting the wavelengths of the multiple optical carriers, multiple passbands are merged into a single passband with a broadened bandwidth. By varying the number of the optical carrier, the bandwidth can be adjusted. The central frequency can be tuned by adjusting the wavelength of the multiple optical carriers simultaneously. A single-passband filter implemented by two optical carriers is experimentally demonstrated.

A tunable comb filter using single-mode/multimode/polarization-maintaining-fiber-based Sagnac fiber loop

A novel tunable comb filter composed of a single-mode/multimode/polarization-maintaining-fiber-based Sagnac fiber loop is proposed and experimentally demonstrated. The filter tunability is achieved by rotating the polarization controller. The spectral shift is dependent on rotation direction and the position of the polarization controller. In addition, the adjustable range achieved by rotating the half-wave-plate polarization controller is twice higher than that of the quarter-wave-plate one.

All-fibre flat-top comb filter based on high-birefringence photonic crystal fibre loop mirror

A novel all-fibre flat-top comb filter based on a high birefringence photonic crystal fibre loop mirror is proposed and demonstrated. We simulate theoretically its output spectra and experimentally realize a flat-top output with a high extinction ratio. Compared to filters consisting of the conventional Panda polarization maintaining fibre, filters based on a high birefringence photonic crystal fibre loop mirror have better temperature stability. This kind of filter can be expected to be used widely in Wavelength-division-multiplexing(WDM) systems in the future.

一种适用于复杂电网下的高精度锁相环

针对现有并网逆变器在电网电压谐波复杂的情况下难以精确锁定电压频率和相位的问题,结合传统锁相环结构与自适应算法的理论提出一种高精度的锁相方法。依据对传统锁相环在复杂电网下的弊端分析,确定了锁相环采用传统低通滤波器、带通滤波器时的滤波效果与延时的矛盾关系。根据最小均方算法的高自适应特性与快速跟踪特点,结合锁相环中坐标变换公式,确定算法的输入输出以及权重矩阵,构建基于派克变换的最小均方算法矩阵模型。通过将所需的电压正序分量设置为不断更新的权重矩阵来进行高精度的滤波,同时通过引入均方瞬时误差和自相关估计均值来进行变步长控制,提高滤波更新速度,以适用于复杂程度不确定的电网电压进行自适应滤波锁相。对仿真和样机实验的结果表明:采用基于派克变换的最小均方算法的改进型双二阶广义积分锁相方法,可以在不降低动态响应速度的前提下,提高锁相环的滤波效果,进而提高并网逆变器在电网畸变严重场景下锁定电压频率和相位的跟踪精度。

Novel Control Strategy for Multi-Level Active Power Filter without Phase-Locked-Loop

Active power filter (APF) using novel virtual line-flux-linkage oriented control strategy can not only realizes no phase-locked-loop (PLL) control, but also achieves a good inhibitory effect to interfere. However, there are some problems in the conventional method, such as the error of amplitude, the shift of phase angle and the non-determinacy of initial oriented angle. In this paper, two one-order low-pass filters are adopted instead of the pure integrator in the virtual line-flux-linkage observer, which can steady the phase and amplitude. Furthermore, an original scheme of harmonics detection under the rotating coordinate is advanced based on the simplified space vector pulse width modulation (SVPWM) strategy. Meanwhile, by using the new SVPWM algorithm, the voltage space vector diagram of the three-level inverter can be simplified and applied into that of two-level inverter, and this makes the control for Neutral Point potential easier.

基于卡尔曼滤波的改进ADRC风电制动器控制策略研究

为了提高风电制动器的抗干扰能力和控制精度,在传统三闭环系统的基础上,提出改进自抗扰控制并融合卡尔曼滤波算法.在扩张状态观测器中引入速度跟踪情况,将传统的“大带宽、小误差”改进为“小带宽、小误差”,提高观测器的观测效率.在误差反馈控制率中引入新型指数趋近律的滑模控制,增强控制效果.在电流环中引入卡尔曼滤波算法,降低电流噪声.通过MATLAB/Simulink建立风电制动系统的数学模型,与传统自抗扰控制策略和PID控制策略进行对比分析.结果表明:改进后的控制策略提高了响应速度,降低了启动转矩和电流噪声;制动器在不同工况下均展现出来良好的控制效果和抗干扰能力,提升了系统的鲁棒性和动态性能.

考虑MAF延时和前馈补偿的高压直流快速锁相环

同步参考坐标系锁相环是高压直流(high voltage direct current,HVDC)同步触发控制系统中广泛应用的一种窄带宽锁相环,在交流系统故障引起相位跳变情况下,其动态响应缓慢。为增大锁相环的带宽,一种滑动平均滤波器(moving average filter,MAF)被前置于锁相环路,然而MAF本身存在响应延迟,制约了锁相环的同步速度。为了缓解响应延迟问题,文中提出一种考虑MAF延时和前馈补偿的HVDC快速锁相环。首先,利用MAF线性暂态特征预测相位变化,并分别针对故障接入和切除引起的相位跳变问题提出不同的补偿策略;接着,利用不变性原理对锁相环路进行前馈补偿,在负反馈控制和前馈补偿共同构成的复合校正控制系统的作用下,锁相环能够在较小PI参数下实现快速响应;最后,将所提快速锁相环在CIGRE HVDC标准模型和三峡—上海直流工程模型中进行仿真验证。结果表明,该快速锁相环能够有效缓解滤波器响应延迟的制约,缩短失锁时间,进而提高高压直流逆变侧抵御换相失败的能力。

基于主动式阻尼的混合式步进电机转速振荡抑制控制

混合式步进电机因其特殊的机械结构导致自身阻尼极小,在实际运行过程中会发生振荡过大,甚至失步的问题。为提高混合式步进电机的控制品质,提出一种基于主动式阻尼的步进电机转速振荡抑制方法。首先,将电机模型转化至同步旋转dq坐标系,将电流i_d控制恒为额定电流,利用位置误差和速度误差调节电流i_q生成瞬时转矩,抑制电机运行时存在的振荡现象。其次,为实现电机闭环反馈控制,提出一种将同步频率提取滤波器(SFF)与三阶锁相环(PLL~3rd)相结合的无传感器控制方法。SFF可以滤除反电动势信号中的高次谐波,PLL~3rd能消除转速变化过程中的稳态误差。实验证明,该方法有效抑制了步进电机运行过程中的振荡现象,提升了电机的运行品质。

基于暂态响应时间分析与暂稳态模式识别的锁相环参数自适应方法

锁相环的设计对保障交流网络中设备安全运行有着重要意义,锁相环实现方法与参数设计对锁相环的响应时间、抗扰能力等控制特性起到重要影响。本文通过结合小信号频域模型与大信号状态空间模型,分析同步坐标系锁相环的暂稳态响应特性,得出各参数设计对于锁相环控制特性的影响;在理论分析基础上,提出了基于响应时间与暂稳态模式识别的锁相环参数自适应框架。仿真与实验结果验证了所提出的参数自适应方法可以通过实现参数动态调节,达到对锁相环暂态快速响应与稳态抗扰的设计要求。

CMG框架超低速无电流环矢量控制研究

针对控制力矩陀螺框架在超低速工况下存在转速测量精度低、多源扰动力矩及非线性摩擦等问题,提出了基于无电流环矢量控制的超低速驱动控制方法。首先,建立超低速工况下的框架电机的机电模型,设计了无电流环磁场矢量控制器(field-oriented control,简称FOC);其次,针对转速测量精度的问题,设计了转速观测器作为反馈环节。结果表明,与方波驱动法相比,该方法无换相转矩,提高了转速测量精度,且在面对多源扰动、非线性摩擦时具有鲁棒性。仿真和实验结果验证了该方法的可行性和有效性。

基于内环修正CDKF算法的锂电池SOC估计

针对现有中心差分卡尔曼滤波算法(CDKF)每次滤波仅进行一次状态更新,无法充分发挥其修正作用的问题,提出一种基于内环修正的中心差分卡尔曼滤波算法(ILCDKF)。采用带遗忘因子的递推最小二乘法(FFRLS)辨识二阶RC等效电路模型的参数;在CDKF算法的量测更新阶段,依据状态误差协方差矩阵建立状态修正机制,通过内环状态修正以提高滤波精度;通过美国联邦城市运行工况(FUDS)和动态应力测试工况(DST)下的仿真实验来验证所提算法的有效性,结果表明,所提算法与扩展卡尔曼滤波算法(EKF)、无迹卡尔曼滤波算法(UKF)及CDKF相比,在荷电状态(SOC)估计精度和收敛速度方面均有所提升。

基于电荷泵锁相环的快速跳频技术研究

针对传统电荷泵锁相环在跳频锁定过程中锁定时间较长的问题,对传统环路滤波器的结构进行了优化,设计了一种新的环路滤波器结构。通过在环路滤波器上添加辅助预置电压电路和开关动态切换电路,实现了电荷泵锁相环的快速跳频锁定。理论分析表明,使用优化后的环路滤波器的系统锁定时间小于使用优化前环路滤波器的系统锁定时间。实测实验分析表明,使用优化后的环路滤波器的锁定时间缩短为优化前锁定时间的0.38倍(升频跳频)和0.34倍(降频跳频),由此可见,优化的环路滤波器结构可大大缩短系统跳频锁定时间。

一种高频锁相频率合成器的设计与实现

为满足高频率信号基准的需求,设计了5.5GHz频率的锁相频率合成器。采用电荷泵锁相环(CPPLL)为核心器件,组合适配的压控振荡器(VCO),再搭配环路滤波器与反馈网络,并且使用MCU控制板与上位机软件进行参数配置,完成了目标频率的输出。实践证明方案可行有效,输出的信号频率不仅误差小,并且具有较好的杂散抑制,可为同类方案的设计和调试提供一定参考。

基于MGAN环路滤波视频编码技术的监控系统设计

为提高变电站环境监测运行效率,提出一种改进的对抗神经网络环路滤波视频编码技术的环境监控系统。首先,根据系统功能性和非功能性需求,将系统分为视频采集层、边缘计算层、云平台层3大模块,并进行了详细设计;然后,基于生成对抗神经网络(GAN),重点设计了边缘计算层视频编码技术,提出一种多层次的GAN(记为MGAN)环路滤波视频编码技术;对系统功能和非功能进行了测试。结果表明,系统可实现实时监控、多路监控、智能保存和视频编码功能,满足安全性、稳定性、可靠性非功能需求,所设计的基于MGAN的环路滤波视频编码技术能有效提高视频编码质量,进一步提高变电站视频及环境监控系统的运行效率,具有一定的实际应用价值。

Digital implementation and analysis of a high dynamic frequency tracking loop

In the wireless guidance system, the signals that receiver received has obvious Doppler shift for the high dynamic characteristic of the carrier. A new solution of carrier frequency tracking loop with frequency modifying system is put forward. The characteristic of cross product auto frequency control and the second order loop filter in this loop are analyzed. The simulation shows that this loop can accomplish frequency tracking well in high dynamic circumstance.

直流母线小电容永磁同步电机驱动系统网侧电流谐波抑制策略

直流母线采用小电容永磁同步电机驱动系统具有降低成本和延长运行寿命的优势。但在系统运行时网侧电流中存在大量的谐波,这将会影响网侧电流质量。为了改善小电容永磁同步电机(PMSM)驱动系统的网侧电能质量,该文提出一种基于阻抗重塑的有源阻尼控制方法,以抑制网侧电流谐波。通过对驱动系统进行建模,分析影响网侧电流谐波的因素,建立母线电流与网侧电流的数学关系。采用有源阻尼控制方法,提取母线电压谐波信号,以最优电压补偿的方式构建反馈回路,重塑驱动系统的特定频率处的等效阻抗,以实现网侧电流谐波的改善。同时,为了抑制电压补偿模块对电流内环扰动的影响,设计电流环级联双频陷波器,并通过系统极点图进行了稳定性分析。仿真结果和实验分析验证了所提控制方法的有效性。