Double-ring high-frequency common-mode switching oscillation current sensor for inverter-fed machine winding insulation monitoring

Insulation failure significantly contributes to the unpredictable shutdown of power equipment.Compared to the partial discharge and high-frequency(HF)injection methods,the HF common-mode(CM)leakage current method offers a non-intrusive and highly sensitive alternative.However,the detection of HF CM currents is susceptible to interference from differential-mode(DM)currents,which exhibit high-amplitude and multifrequency components during normal operation.To address this challenge,this paper proposes a double-ring current sensor based on the principle of magnetic shielding for inverter-fed machine winding insulation monitoring.The inner ring harnesses the magnetic aggregation effect to isolate the DM current magnetic field,whereas the outer ring serves as the magnetic core of the Rogowski current sensor,enabling HF CM current monitoring.First,the magnetic field distributions of the CM and DM currents were analyzed.Then,a correlation between the sensor parameters and signal-to-noise ratio of the target HF CM current was established.Finally,an experimental study was conducted on a 3-kW PMSM for verification.The results indicate that the proposed double-ring HF CM sensor can effectively mitigate DM current interference.Compared to a single-ring sensor,a reduction of approximately 40%in the DM component was achieved,which significantly enhanced the precision of online insulation monitoring.

A Hybrid Five-Level Single-Phase Rectifier with Low Common-Mode Voltage

Rectifiers with high efficiency and high power density are crucial to the stable and efficient power supply of 5G communication base stations,which deserves in-depth investigation.In general,there are two key problems to be addressed:supporting both alternating current(AC)and direct current(DC)input,and minimizing the common-mode voltage as well as leakage current for safety reasons.In this paper,a hybrid five-level single-phase rectifier is proposed.A five-level topology is adopted in the upper arm,and a half-bridge diode topology is adopted in the lower arm.A dual closed-loop control strategy and a flying capacitor voltage regulation method are designed accordingly so that the compatibility of both AC and DC input is realized with low common voltage and small passive devices.Simulation and experimental results demonstrate the effectiveness and performance of the proposed rectifier.

THE DESIGN OF BALANCED AMPLIFIER BASED ON COMMON-MODE FEEDBACK

The balanced operational amplifier including its merits and designing methods is discussed by comparing its performance to a conventional differential output amplifier when used in a single balanced stage. A balanced OTA circuit design is also presented.

Regenerative Braking Energy Recovery System of Metro Train Based on Dual-Mode Power Management

In order to fully utilize the regenerative braking energy of metro trains and stabilize the metro DC traction busbar voltage,a hybrid regenerative braking energy recovery system with a dual-mode power management strategy is proposed.Firstly,the construction of the hybrid regenerative braking energy recovery system is explained.Then,based on the power demand of low-voltage load in metro stations,a dual-mode power management strategy is proposed to allocate the reference power of each system according to the different working conditions,and the control methods of each system are set.Finally,the correctness and effectiveness of the dual-mode strategy are verified through simulation,and the proposed braking energy utilization scheme is compared with other singleform utilization schemes.The results illustrate that the hybrid system with the dual-mode strategy can effectively recycle the regenerative braking energy of metro train and inhibit the busbar voltage fluctuation;the proposed braking energy utilization scheme has certain advantages on energy recovery and DC bus voltage stabilization compared with other single-form schemes;the proposed power management strategy can correctly allocate the reference power of each system with a lower construction cost.

Novel Modulation Strategy to Achieve Neutral-point Voltage Balance, Common-mode Voltage, and Switching Loss Reduction for Neutral-point Clamped Three-level Inverters

Carrier-based pulse width modulation (CBPWM) and virtual space vector pulse width modulation (VSVPWM) are briefly reviewed for neutral-point-clamped three-level inverters (NPC TLI). A new modulation strategy referred to as N3S_CBPWM is then proposed to simultaneously consider multiple goals, such as the-neutral-point voltage (NPV) balance, switching loss, and common-mode voltage (CMV) reduction. For N3S_CBPWM in each switching cycle, the three-phase switching actions are zero, one, and two. In addition, the constraint conditions of the modulation waves are provided based on the reduction of the CMV. Subsequently, N3S_CBPWM, CBPWM, and VSVPWM are compared in terms of the NPV balance capability, switching loss, and CMV reduction. Finally, the feasibility and superiority of the proposed N3S_CBPWM are verified experimentally.

一种高性能共模反馈CMOS运算放大器

介绍了一种具有高增益,高电源抑制比(CMRR)和大带宽的两级共源共栅运算放大器。此电路在两级共源共栅运算放大器的基础上增加共模反馈电路,以提高共模抑制比和增加电路的稳定性。电路采用0.35μm标准CMOS工艺库,在Cadence环境下进行仿真。结果显示,该放大器增益可达到101 dB,负载电容为10 pF时,单位增益带宽大约为163 MHz,共模抑制比可达101dB,电路功耗仅为0.5 mW。

Realization of Fully Differential Fourth-Order Bessel Filter with Accurate Group Delay

A fully differential R-MOSFET-C fourth-order Bessel active lowpass filter employing fully differential operational amplifier,passive resistors,and current-steering MOS transistors as a variable resistor is proposed.This proposed implementation relies on the tunability of current-steering MOS transistors operating in the triode region counteracting the concert deviation of resistor in the integrated circuit manufacturing technology in orde r that the group delay of Bessel active filter could be designed accurately.The amplifier is not only with voltage common-mode negative feedback,but also with current common-mode negative feedback,which will benefit for the stability of its D C operating point.0.75μs group delay fourth-order Bessel lowpass filter,whic h is synthesized according to passive doubly terminated RLC prototype lowpass filter,demonstrates better than -65dB THD using 100kHz,2.5V pp signal in Taiwan UMC 2P2M(2-poly,2-metal)5.0V,0.5μm CMOS technology.

集成过抽样∑-△A/D转换器设计研究

运用CMOS集成电路设计处理对象为语音信号的二阶∑-DA/D转换器。采用全差动设计、共模反馈电路和开关电容积分器实现二阶∑-DA/D转换器。

一种低功耗全差分交叉耦合环形振荡器设计

提出了芯片内部振荡器的一种设计方案,该振荡器采用了全差分环形振荡器的结构,其延迟单元使用了共模反馈和交叉耦合晶体管对对频率进行调节校准,抑制相位噪声能力强。还提出了一种新型的基准源结构,这种结构产生的电流温漂系数小、电源抑制比高。该设计基于CSMC 0.35μm CMOS工艺,测试结果表明,在3.3V的低电源电压下,振荡频率抖动范围很小,中心频率在11.4MHz,功耗仅为1.4mW。

用于MEMS微电容检测的全差分放大器

设计了一种用于MEMS电容传感器的低噪声低失调全差分运算放大器。微传感器传感电容一般很小,传感电容的变化更小。低噪声低失调放大器大大提高了整个传感器检测电路精度。该放大器采用连续时间共模反馈方法稳定共模输出、低阻结点斩波和动态匹配方法以期达到有稳定输出的低噪声低失调全差分放大器,给出基于HJTC 0.18μm CMOS 1P6M工艺的仿真结果,经过精心设计,各项指标达到或超过应用要求。

Data-processing induced GPS-positioning error

Global Positioning System data processing is affected by many non-tectonic factors, including the common-mode errors （CME） in station-position time series. The characteristics and origins of CME are still not clear, due to uneven distribution of global GPS networks and the lack of reliable data of the position time series. In this work, data from 241 continuous GPS stations were reprocessed in a consistent way and the results were compared with those generated at Jet Propulsion Laboratory （JPL）. Improvements of residual positions were obtained for many low-quality stations, especially those located in Asia and Australia.

Dynamic Linkage between the North Pacific and the Tropical Pacific:Atmosphere-Ocean Coupling

In this study, dynamic linkage of atmosphere-ocean coupling between the North Pacific and the tropical Pacific was demonstrated using a large number of ensemble perturbed initial condition experiments in a fully coupled fast ocean-atmosphere model （FOAM）. In the FOAM model, an idealized mixed layer warming was initiated in the Kuroshio-Oyashio extension region, while the ocean and atmosphere remained fully coupled both locally and elsewhere. The modeling results show that the warm anomalies are associated with anomalous cyclonic winds, which induce initial warming anomalies extending downstream in the following winter. Then, the downstream warming spreads southwestward and induces SST warming in the equatorial Pacific via surface wind-evaporation-SST feedback. Warming in the tropical Pacific is further reinforced by Bjerknes＇ feedback.

Cyber Attack Protection and Control of Microgrids

Recently, the smart grid has been considered as a next-generation power system to modernize the traditional grid to improve its security, connectivity, efficiency and sustainability.Unfortunately, the smart grid is susceptible to malicious cyber attacks, which can create serious technical, economical, social and control problems in power network operations. In contrast to the traditional cyber attack minimization techniques, this paper proposes a recursive systematic convolutional(RSC) code and Kalman filter(KF) based method in the context of smart grids.Specifically, the proposed RSC code is used to add redundancy in the microgrid states, and the log maximum a-posterior is used to recover the state information, which is affected by random noises and cyber attacks. Once the estimated states are obtained by KF algorithm, a semidefinite programming based optimal feedback controller is proposed to regulate the system states, so that the power system can operate properly. Test results show that the proposed approach can accurately mitigate the cyber attacks and properly estimate and control the system states.

Influence of motor cable on common-mode currents in an inverter-fed motor drive system

Induction motor drive systems fed by cables are widely used in industrial applications. However, high-frequency switching of power devices will cause common-mode（CM） voltages during operation, leading to serious CM currents in the motor drive systems. CM currents through the cables and motors in the drive systems can cause electromagnetic interference（EMI） with the surrounding electronic equipment and shorten the life of induction motors. Therefore, it is necessary to analyze the CM currents in motor drive systems. In this paper, high-frequency models of unshielded and shielded power cables are formulated. The frequency-dependent effects and mutual inductances of the cables are taken into account. The power cable parameters are extracted by the finite element method and validated by measurements. High-frequency models of induction motors and inverters are introduced from existing works. The CM currents at the motor and inverter terminals are obtained, and the influence of the cable length and cable type on the CM currents is analyzed. There is a good agreement between the experimental results and the CM currents predicted by the proposed models.

Common Mode EMI Reduction through PWM Methods for Three-Phase Motor Controller

Pulse-width sequences are identified as the determining factor for common-mode(CM)voltage,which together with CM path generate CM current.This paper introduces a series of pulse-width modulation(PWM)methods,which are focusing on reducing CM noise of three-phase inverters as motor controller.Firstly,theoretic analysis and PWM reduction methods of CM voltage for general three-phase two-level inverters are introduced.Analysis results indicate that the realization of CM noise reduction should take switching frequency and loop impedance into consideration together to avoid CM resonant phenomenon.The regular three-phase two-level inverter is incapable of eliminating CM voltage because of the limitation of topology.Then,optimal PWM methods applied to for advanced topologies can be utilized to eliminate the CM voltage theoretically.Two typical typologies presented in this paper are three-level inverters and paralleled inverters.Three-level inverters can achieve zero-CM output voltage by selecting zero-CM voltage vectors at the expense of power quality.However,for paralleled inverters,zero-CM PWM method is able to achieve zero CM voltage output,as well as the improved output current harmonics and voltage balancing.

Hybrid Common-mode EMI Filter Design for Electric Vehicle Traction Inverters

A feedforward current-sense current-compensation(CSCC)active EMI filter(AEF)for the direct current-side common-mode(CM)electromagnetic interference(EMI)suppression of high-power electric vehicle traction inverters is analyzed and designed.A detailed design of the components with formulas is provided based on an analysis of the CSCC AEF,including the CSCC AEF topology and its implementation.The feedforward active filter stage was implemented using a simple current transformer and a small circuit board.Only a small passive filter with a high resonant frequency is required for high-frequency noise attenuation.The filter’s effectiveness was validated using the simulation results and experimental measurements.

NOVEL DESIGN OF A BIOELECTRIC AMPLIFIER WITH MINIMIZED MAGNITUDE AND PHASE ERRORS

A new design of a bioelectric amplifier that has better parameters than conventional designs is presented. The design allows the construction of bioelectric amplifier with improved parameters in terms of common-mode rejection ratio and phase and magnitude errors. The voltage gain is easily adapted to a wide range of biomedical applications. The experimental and simulation results of the designed bioelectric amplifier are also included.

Design of a wideband common-mode filter using approximate closed-loop pattern of compact C-shaped defected ground structure

A compact common-mode filter is proposed to suppress common-mode noise for application of high-speed differential signal traces. The filter adopts one big C-shaped defected ground structure （DGS） cell in the left of ground plane and two small C-shaped DGS cells with opposite direction in the right of ground plane. Because these DGS cells have different dimensions, the filter has three adjacent equivalent resonant points, which can suppress wideband common-mode noise effectively. The left C-shaped DGS and its adjacent C-shaped DGS cell form an approximate closed structure, which can efficiently reduce the influence of the mutual capacitance. The filter provides a common-mode suppression from 3.6 GHz to 14.4 GHz over 15 dB while it has a small size of 10 minx 10 mm. The fractional bandwidth of the filter is 120%, and the differential signals still keep good signal integrity. The experimental results are in good agreement with the simulated results.

Dual-current-injection CSCC Active Common-mode EMI Filters with High Insertion Loss for DC-DC Converters

With the increase in the switching frequency and power density,DC-DC converters encounter more severe electromagnetic interference(EMI)problems.To suppress the common-mode EMI generated by converters,as well as maintain the high-power-density of converters,the active EMI filter(AEF)has attracted increasing interest owing to its small volume.The EMI suppression effect of the common single-stage single-sense single-injection AEF is confined because of the limited insertion loss,and the volume of the multi-stage AEF will be bulky.To solve this problem,this paper proposes a compact dual-current-injection current-sense current-compensation(DCJ-CSCC)AEF to increase the insertion loss in the entire conducted EMI frequency band,as well as considering the volume of the AEF.The structure and operating principle of the proposed AEF are introduced.Finally,taking a boost converter as an example,the effectiveness and advantages of the proposed DCJ-CSCC AEF were verified through a simulation and experiment,the results show that the proposed AEF has a better EMI suppression effect on the entire conducted EMI frequency band with a similar volume compared with existing single-injection feedforward current-sense current-compensation(FF-CSCC)and feedback current-sense current-compensation(FB-CSCC)AEFs.This paper provides a new selection for EMI suppression in DC-DC converters.

Modified coupled map car-following model and its delayed feedback control scheme

A modified coupled map car-following model is proposed, in which two successive vehicle headways in front of the considering vehicle is incorporated into the optimal velocity function. The steady state under certain conditions is obtained. An error system around the steady state is studied further. Moreover, the condition for the state having no traffic jam is derived. A new control scheme is presented to suppress the traffic jam in the modified coupled map car-following model under the open boundary. A control signal including the velocity differences between the following and the considering vehicles, and between the preceding and the considering vehicles is used. The condition under which the traffic jam can be well suppressed is analysed. The results are compared with that presented by t^onishi et al. （the KKH model）. The simulation results show that the temporal behaviour obtained in our model is better than that in the KKH model. The simulation results are in good agreement with the theoretical analysis.