Digital fixed-frequency hysteresis current control of a BLDC motor applied for aerospace electrically powered actuators

In the conventional cascade control structure of aerospace electrically powered actuators, the current（or electromagnetic torque） loop plays a critical role in realizing a rapid response for a digitally controlled Brush Less Direct Current（BLDC） motor. Hysteresis Current Control（HCC） is an effective method in improving the performance of current control for a BLDC motor.Nevertheless, the varying modulating frequency in the traditional HCC causes severe problems on the safety of power devices and the electromagnetic compatibility design. A triangular carrier-based fixed-frequency HCC strategy is expanded by relaxing the constraints on the rising and descending rates of the winding current to advance the capability of HCC to realize fixed-frequency modulation in the steady state. Based on that, a new flexible-bound-size quasi-fixed-frequency HCC is proposed, and the range feasible to realize fixed-frequency modulation control can cover the entire running process in the steady state. Meanwhile, a corresponding digital control strategy is designed,and four digitalization rules are proposed to extend the capacity to achieve fixed-frequency modulation control to the unsteady working state, that is, a novel fixed-frequency modulation is realized.Simulation and experimental results prove the effectiveness of this improved fixed-frequency HCC strategy.

Magnetoresistance hysteresis in the superconducting state of kagome CsV_(3)Sb_(5)

The hysteresis of magnetoresistance observed in superconductors is of great interest due to its potential connectionwith unconventional superconductivity.In this study,we perform electrical transport measurements on kagome superconductorCsV_(3)Sb_(5)nanoflakes and uncover unusual hysteretic behavior of magnetoresistance in the superconducting state.This hysteresis can be induced by applying either a large DC or AC current at temperatures(T)well below the superconductingtransition temperature(T_(c)).As T approaches T_(c),similar weak hysteresis is also detected by applying a smallcurrent.Various scenarios are discussed,with particular focus on the effects of vortex pinning and the presence of timereversal-symmtery-breaking superconducting domains.Our findings support the latter,hinting at chiral superconductivityin kagome superconductors.

Enhanced superelasticity and reversible elastocaloric effect in nano-grained NiTi alloys with low stress hysteresis

Solid-state cooling technologies have been considered as potential alternatives for vapor compression cooling systems.The search for refrigeration materials displaying a unique combination of pronounced caloric effect,low hysteresis,and high reversibility on phase transformation was very active in recent years.Here,we achieved increase in the elastocaloric reversibility and decrease in the friction dissipation of martensite transformations in the superelastic nano-grained NiTi alloys obtained by cold rolling and annealing treatment,with very low stress hysteresis(6.3 MPa)under a large applied strain(5%).Large adiabatic temperature changes(△T_(max)=16.3 K atε=5%)and moderate COP_(mater)values(maximum COP_(mater)=11.8 atε=2%)were achieved.The present nano-grained NiTi alloys exhibited great potential for applications as a highly efficient elastocaloric material.

Noncovalent cross-linked engineering hydrogel with low hysteresis and high sensitivity for flexible self-powered electronics

In this study,the hydrogel network was reinforced by covalent-like hydrogen bonding,and the strong binding ability of boron-nitrogen coordination served as the main driving force.Among them,acrylamide(AM)and 3-acrylamidophenylboronic acid(AAPBA)were the main body,and the numerous hydroxyl groups in the trehalose(Treh)molecule and other polymer groups formed strong hydrogen bonding interactions to improve the mechanical properties of the PAM/PAAPBA/Treh(PAAT)hydrogel and ensured the simplicity of the synthesis process.The hydrogel possessed high strain at break(1239%),stress(64.7 kPa),low hysteresis(100%to 500%strain,corresponding to dissipation energy from 1.37 to 7.80 kJ/m^(3)),and outstanding cycling stability(retained more than 90%of maximum stress after 200 ten-sile cycles).By integrating carbon nanotubes(CNTs)into PAAT hydrogel(PAATC),the PAATC hydrogel with excellent strain response performance was successfully constructed.The PAATC conductive hydro-gel exhibited high sensitivity(gauge factor(GF)=10.58 and sensitivity(S)=0.304 kPa^(-1)),wide strain response range(0.5%-1000%),fast response time(450 ms),and short recovery time(350 ms),excellent fatigue resistance,and strain response stability.Furthermore,the PAATC-based triboelectric nanogener-ator(TENG)displayed outstanding energy harvesting performance,which shows its potential for appli-cation in self-powered electronic devices.

A Selective‑Response Hypersensitive Bio‑Inspired Strain Sensor Enabled by Hysteresis Effect and Parallel Through‑Slits Structures

Flexible strain sensors are promising in sensing minuscule mechanical signals,and thereby widely used in various advanced fields.However,the effective integration of hypersensitivity and highly selective response into one flexible strain sensor remains a huge challenge.Herein,inspired by the hysteresis strategy of the scorpion slit receptor,a bio-inspired flexible strain sensor(BFSS)with parallel through-slit arrays is designed and fabricated.Specifically,BFSS consists of conductive monolayer graphene and viscoelastic styrene–isoprene–styrene block copolymer.Under the synergistic effect of the bio-inspired slit structures and flexible viscoelastic materials,BFSS can achieve both hypersensitivity and highly selective frequency response.Remarkably,the BFSS exhibits a high gage factor of 657.36,and a precise identification of vibration frequencies at a resolution of 0.2 Hz through undergoing different morphological changes to high-frequency vibration and low-frequency vibration.Moreover,the BFSS possesses a wide frequency detection range(103 Hz)and stable durability(1000 cycles).It can sense and recognize vibration signals with different characteristics,including the frequency,amplitude,and waveform.This work,which turns the hysteresis effect into a"treasure,"can provide new design ideas for sensors for potential applications including human–computer interaction and health monitoring of mechanical equipment.

A Hybrid Compensation Scheme for the Input Rate-Dependent Hysteresis of the Piezoelectric Ceramic Actuators

A hybrid compensation scheme for piezoelectric ceramic actuators(PEAs)is proposed.In the hybrid compensation scheme,the input rate-dependent hysteresis characteristics of the PEAs are compensated.The feedforward controller is a novel input rate-dependent neural network hysteresis inverse model,while the feedback controller is a proportion integration differentiation(PID)controller.In the proposed inverse model,an input ratedependent auxiliary inverse operator(RAIO)and output of the hysteresis construct the expanded input space(EIS)of the inverse model which transforms the hysteresis inverse with multi-valued mapping into single-valued mapping,and the wiping-out,rate-dependent and continuous properties of the RAIO are analyzed in theories.Based on the EIS method,a hysteresis neural network inverse model,namely the dynamic back propagation neural network(DBPNN)model,is established.Moreover,a hybrid compensation scheme for the PEAs is designed to compensate for the hysteresis.Finally,the proposed method,the conventional PID controller and the hybrid controller with the modified input rate-dependent Prandtl-Ishlinskii(MRPI)model are all applied in the experimental platform.Experimental results show that the proposed method has obvious superiorities in the performance of the system.

RELIABLE HYSTERESIS CURRENT CONTROLLED DUAL BUCK HALF BRIDGE INVERTER

A highly efficient and re liable topology-dual buck half bridge inverter (DBI) is introduced. The existenc e of discontinuous conduction mode (DCM) operation state requires the bias of in du ctor current for DBI implemented with linear controllers like ramp comparison SP WM (RCSPWM) controllers. A novel operation scheme for DBI and a hysteresis curre nt controlled dual buck half bridge inverter (HCDBI) are proposed. The bias curr ent required by RCSPWM DBI is eliminated and conduction losses are dramatically reduced. HCDBI has greatly improved the modulation performance in DCM region for the benefit of its excellent command tracking capability. The operational schem e and control strategy are presented. Power losses of the conventional half brid ge inverter (CHBI) and HCDBI are compared with mathematical computation, and exp erimental verification is also executed. Both calculational and experimental res ults verify that HCDBI has a superior switching performance over CHBI. Its exce llent high frequency operational capacity provides another access to realize high fre quency operation of inverters.

一类微分项中含Hysteresis的抛物型方程

本文通过引入导出算子分离 Hysteresis与微分 ,证明了一个微分项中含Hysteresis的抛物型方程古典解的存在唯一性 .

EFFECT OF FIBER FAILURE ON QUASI-STATIC UNLOADING/RELOADING HYSTERESIS LOOPS OF CERAMIC MATRIX COMPOSITES

The two-parameter Weibull model is used to describe the fiber strength distribution.The stress carried by the intact and fracture fibers on the matrix crack plane during unloading/reloading is determined based on the global load sharing criterion.The axial stress distribution of intact fibers upon unloading and reloading is determined based on the mechanisms of fiber sliding relative to matrix in the interface debonded region.The interface debonded length,unloading interface counter slip length,and reloading interface new slip length are obtained by the fracture mechanics approach.The hysteresis loops corresponding to different stresses considering fiber failure are compared with the cases without considering fiber failure.The effects of fiber characteristic strength and fiber Weibull modulus on the fiber failure,the shape,and the area of the hysteresis loops are analyzed.The predicted quasi-static unloading/reloading hysteresis loops agree well with experimental data.

运动心电图试验ST/HR滞后(Hysteresis)与冠心病之间关系的研究

目的 探讨平板心电图运动试验ST/HR滞后与冠心病之间的关系及临床意义。方法 对可疑冠心病的136例患者在1周之内分别进行了平板运动试验和冠状动脉造影检查,并计算出心电图运动试验ST/HR滞后最大值。结果 136例患者,传统的ST段压低标准,阳性者86例,可疑阳性21例,其中真阳性78例;ST/HR滞后标准,阳性者83例,真阳性75例。传统的ST段压低标准与ST/HR滞后标准诊断冠心病的敏感性、特异性、准确性分别为714%、862%、758%和903%、868%、890%。结论 平板心电图运动试验ST/HR滞后标准能明显的改进心电图运动试验对冠心病的诊断作用,是检测心肌缺血有价值的指标。

一个主部含Hysteresis的抛物型方程

引入导出算子分离Ｈｙｓｔｅｒｅｓｉｓ与微分，证明了一个主部含Ｈｙｓｔｅｒｅｓｉｓ的抛物型方程古典解的存在唯一性。

一个具Hysteresis的电报方程（英文）

讨论一个具Hysteresis的电报方程.首先给出Ishlinskiǐhysteresis算子的一些性质,然后得到这个方程C1+α,α强解存在性.

一个具Hysteresis的拟线性抛物方程

讨论一个具Hysteresis的电报方程。首先给出了Ishlinskiǐ hysteresis算子的一些性质,然后得到了这个方程C1+α,α强解存在性。

两个具有Hysteresis的发展方程(英文)

研究如下两个具有Hysteresis的发展方程 :utt-Δu +F(u) =f,ut- (F(ux) ) x=f.通过引进Hysteresis算子的逆 ,证明了第一个方程一维初值问题古典解和多维初边值问题强解的存在惟一性以及第二个方程一维初边值问题光滑强解的存在性 .

一个具有Hysteresis的双曲方程(英文)

讨论了一个具有 Hysteresis的双曲方程 。

低温固体界面间接触导热“hysteresis”现象的研究

文中以强化低温固体界面间的接触导热为出发点 ,实验测定了低温环境下两种金属界面在过度加载前后的接触热导值 ,指出过度加载是一种经济有效的强化导热方法 ,对卸载过程接触热导率大于同次加载过程接触热导的“hysteresis”

一个含Hysteresis两相Stefan问题

考虑了一个具有表面张力、动力条件和 Hysteresis的两相 Stefan问题 ,并得到这个问题关于时间的局部古典存在唯一性。

一个含Hysteresis的波动方程

讨论了IshIinskiǐhysteresis算子的性质,给出了一个具弹塑性阻尼的波动方程的古典解存在唯一性.

一类含hysteresis的自控系统模型

很多自控系统都存在时滞效应,描述有害物质反应扩散过程的数学模型就是某种含时滞的微分方程。由于迟滞因子的非线性特性,如函数的许多优良性质被破坏,使得许多具有迟滞特性的模型几乎无法进行分析,因此在一般自控系统的建模中,人们都略去时滞因素。首先根据空气净化系统的功能原理引进了一类时滞算子,通过一系列细致分析给出了时滞算子的若干重要性质。然后主要利用不动点定理证明了含时滞的微分方程整体古典解存在唯一性,最后提出了精细地测算净化设备投资与效益的决策模型。

一个主部含Hysteresis的两相Stefan问题

考虑一个具有表面张力和动力条件，且主部含有Ｈｙｓｔｅｒｅｓｉｓ的两相Ｓｔｅｆａｎ问题，并得到这个问题关于时间的局部古典解存在唯一性。