ROBUST ADAPTIVE CONTROL SCHEME FOR IMPROVING LOW-SPEED PROFILE TRACKING PERFORMANCE OF HYBRID STEPPING MOTOR SERVO DRIVE

A robust adaptive control approach is presented to improve the performance of the control scheme proposed in the authors＇ previous work, aiming at producing a low ripple hybrid stepping motor servo drive for precision profile tracking at a low speed. In order to construct a completely integrated control design philosophy to reduce torque ripple and at the same time to enhance tracking performance, the properties of nonlinear uncertainties in the system dynamics are uncovered, and then incorporated into the design of the controller. The system uncertainties concerned with ripple dynamics and other external disturbances are composed of two categories. The first category of uncertainties with linear parameterization arising from the detention effect is dealt with by the wellknown adaptive control method. A robust adaptive method is used to deal with the second category of uncertainties resulting from the non-sinusoidal flux distribution. The μ-modification scheme is used to cease parameter adaptation by the robust adaptive control law, thus ensuring that the trajectory tracking error asymptotically converges to a pre-specified boundary. Experiments are performed with a typical hybrid stepping motor to test its profile tracking accuracy. Results confirm the proposed control scheme.

Contribution to the Full 3D Finite Element Modelling of a Hybrid Stepping Motor with and without Current in the Coils

The paper presents our contribution to the full 3D finite element modelling of a hybrid stepping motor using COMSOL Multiphysics software. This type of four-phase motor has a permanent magnet interposed between the two identical and coaxial half stators. The calculation of the field with or without current in the windings (respectively with or without permanent magnet) is done using a mixed formulation with strong coupling. In addition, the local high saturation of the ferromagnetic material and the radial and axial components of the magnetic flux are taken into account. The results obtained make it possible to clearly observe, as a function of the intensity of the bus current or the remanent induction, the saturation zones, the lines, the orientations and the magnetic flux densities. 3D finite element modelling provide more accurate numerical data on the magnetic field through multiphysics analysis. This analysis considers the actual operating conditions and leads to the design of an optimized machine structure, with or without current in the windings and/or permanent magnet.

Static-torque Characteristics of Three-phase Hybrid(HB) Stepping Motors and Influence of Way of Winding Connection on Operating Characteristics of Motors of This Kind

The paper presents the static-torque characteristics of three-phase hybrid stepping motors and discusses the influence of way of winding connection on operating characteristics of motors of this kind.

Research on simulation system of virtual three-phase stepping motor

To change the current phenomenon of ＂Being an armchair strategist＂ in the research of a stepping motor, the virtual simu- lation system of stepping motor was developed using virtual reality technique. The basic principle of stepping motor was expounded. The development strategy of the simulation software is introduced. Some key problems and their solutions, including coordinate transformation of rotor and order of on-off electricity for stator, were put forward in system development. Finally, there are three virtual simulation examples of the on-off electricity way in this paper. This work provides a valuable auxiliary tool for the study of the stepping motor.

Linear Piezoelectric Stepping Motor with Broad Operating Frequency

The existing resonant linear piezoelectric motors must operate with high working voltage in resonant condition,resulting in their narrow operating frequency range and poor running stability.Here,with the large displacement output characteristics of piezoelectric stacks,the trajectory at the drive foot of stator is firstly produced with two space quadrature piezoelectric actuators excited by sawtooth wave and square wave.Secondly,the friction drive principle of motor is used to analyze the working mechanisms of the continuous stepping motion.Finally,the motor prototype is designed and experiments are carried out.The experimental result shows that the motor can stably operate within the scope of 350 Hz to 750 Hz.When the excitation voltage is 30 Vand pre-load is 3Nor10 N,the lateral amplitude of the drive foot is approximately 4μm and the stable average interval ranges from3.1μm to 3.2μm with the error rate of 5%—7.5%.

MINIMUN TIME OPTIMAL CONTROL OF STEPPING MOTOR

The paper describes a new method of the stepping motor moimun time optimal control with closed-loop control. A mathematical model and optimal control strategy for the optimal control of stepping motor are proposed. Realizing technology for accelerating

Six-step Voltage Control of PM Brushless AC Motors under High Speed Flux-weakening Operation for EV/HEV Applications

The torque-speed characteristics of brushless motor having an interior permanent magnet rotor and a sinusoidal back-emf waveform are compared experimentally when it is operated in brushless AC(BLAC) mode and brushless DC (BLDC) modes with both 2-phase,120° conduction(BLDC-120) and 3-phase,180° conduction(BLDC-180).Particular emphasis is on high-speed,six-step voltage controlled,flux-weakening operation.It is shown that for EV/HEV applications,even for interior PM brushless motors which have sinusoidal back-emf waveforms,in order to achieve maximum torque per ampere capability over wide operation speed range,it is advantageous to employ a hybrid operation mode-BLAC operation in the constant torque region and six-step voltage control(BLDC-180 operation,together with current phase control) in the flux-weakening region.

Numerical Modeling of the Coupled Electromagnetic and Mechanical Phenomena of Linear Stepping Motors

In this paper, we propose an electromagnetic-mechanical model based on the finite element and Macro-Element (ME) technique to analyse and study the dynamic characteristics of a Tubular Linear Switched Reluctance Stepping Motor (LSRSM). After the resolution of the non-linear electromagnetic equation governing the behaviour of the different materials of the motor using the nodal-based finite element method, this equation is then coupled to the mechanical equation firstly through the magnetic force computed by Maxwell stress tensor, and secondly by the modified flux distribution due to the moving part. Because of the precision required in the mobile part displacement and the very small air gap of stepping motors, the simulation of the movement is assured by the Macro-Element (ME) technique compared to other movement techniques that present many disadvantages. The validity of the developed model is verified through the comparison of the computed displacement of the LSRSM moving part with those given experimentally [2]. The Results shows satisfactory agreement. The obtained dynamic characteristics, particularly the starting magnetic force, are obtained by considering two values of the supplying currents.

A hybrid stepping motor system with dual CPU

An indirect method of measuring the rotor position based on the magnetic reluctance variation is presented in the paper. A single-chip microprocessor 80C196KC is utilized to compensate the phase shift produced by the process of position signals. At the same time, a DSP (Data Signal Processor) unit is used to realize the speed and current closed-loops of the hybrid stepping motor system. At last, experimental results show the control system has excellent static and dynamic characteristics.

A Step Motor Driver For the Let-off Mechanism of Looms

It is simple with good quality,and versatile with low costto use a step motor drive for the let-off mechanism ofweaving machines.This paper deals with the investiga-tion of this mechanism about the warp tension detectingand the design of the step motor drive system,which ispracticable,reliable and with low power consumption.So it is worthwhile to spread and push forward its appli-cation.

Development of an underactuated prosthetic hand with the step motor

We present the development of a novel prosthetic hand based on the underactuated mechanism. The aim is focused on increasing its dexterity while keeping the same dimension and weight of a traditional prosthetic device. The hybrid step motor is used as the actuator, which enables the finger to keep enough high contact torque on the grasped object with less energy consumption provided by the holding torque. The grasping force of the finger is estimated from the base joint torque, and the adoption of impedance control has provided compliance in the grasping. Also a parallel observer is used to switch over between the impedance control and the torque holding mode. The experimental results show the effectiveness of the design and control strategy.

Numerical simulation of flow separation over a backward-facing step with high Reynolds number

Large eddy simulation (LES) explicitly calculates the large-scale vortex field and parameterizes the small-scale vortices.In this study,LES and κ-ε models were developed for a specific geometrical configuration of backward-facing step (BFS).The simulation results were validated with particle image velocimetry (PIV) measurements and direct numerical simulation (DNS).This LES simulation was carried out with a Reynolds number of 9000 in a pressurized water tunnel with an expansion ratio of 2.00.The results indicate that the LES model can reveal largescale vortex motion although with a larger grid-cell size.However,the LES model tends to overestimate the top wall separation and the Reynolds stress components for the BFS flow simulation without a sufficiently fine grid.Overall,LES is a potential tool for simulating separated flow controlled by large-scale vortices.

Detection of rotor position by harmonic back EMF of hybrid step motor

The magnhc network model of a hybrid step motor is established by the air gap rate permeance method,and the expression of harmonic back EMF is deduced, and from the analysis above, a vovel use of harmonic backEMF sed to extract rotor peition is proposed and a new position sensor integral with the motoris designed .Experi-ments verified the correctness of the theorecal analysis. Ths type of rotor position sensor lays a foundation for closed-loop conrol of step motor.

Impact of Geomagnetically Induced Currents Secondary Event on the High-Voltage Synchronous Motors

It is justified that during geomagnetic storms the high voltage synchronous engines are being impacted by high current harmonics of even sequences powered by power transformer due to geo-induced high voltage currents flowed through the windings. Equivalent circuits of step down substation and HV synchronous motors are made for making it possible to consider a saturation of power transformer magnetic system and higher current harmonics availability in stator windings. Analytic expressions for higher current harmonics and extra capacity losses calculation in stator windings are received, as well as the calculation of induction torques allowing to denote a rate of geomagnetic processes impact on synchronous engine operation at various step down substation parameters.

An Experimental Investigation on the Dynamic Behavior of Step Motor Drives

Step motors, compared to other drive systems, are low-cost and easy to use devices. However, despite these undeniable advantages, they are characterized by some critical running conditions, due to the loss of synchronization between the stator＇s magnetic field and the rotor. In order to theoretically investigate such a behavior, several complex mathematical models have been developed, which require several parameters to be defined. For most step motors, such parameters cannot be easily drawn from their data-sheets; on the contrary, in this paper the authors refer to a simplified electro-mechanical model where the most of the parameters are known from data-sheets. The dependence between electrical and mechanical quantities can be investigated by an experimental point of view. At this aim, a specific novel test rig has been designed and developed for either static or dynamic characteristics measurement of small size step motors. In particular, the test rig allow to measure rotor＇s angular position, motor＇s torque, currents flowing in the motor＇s phases. The paper ends with the report of the results of several experimental tests, carried-out on a small-size motor in different running conditions, and with some preliminary remarks on the basis of the measures analysis.

Numerical Study on Claw-pole Electric Motors for Electronic Expansion Valves

电子膨胀阀在变频空调系统中能精确调节制冷剂流量，有助于提高空调系统的能效和改善空调环境的热舒适性。研究电子膨胀阀用爪极永磁步进电机有助于提高电子膨胀阀稳定性和可靠性。对电子膨胀阀的电机力矩特性进行数值分析，在保持转子尺寸、通电电流和定转子之间气隙不变的前提下，通过改变爪极形状尺寸，分析了爪极形状参数对电子膨胀阀用爪极式步进电机白定位力矩和保持力矩的影响，认为在满足一定自定位力矩的前提下，保持力矩越大越好，并以此为基础对电机的爪极尺寸进行了优化，认为合理设计爪极尺寸参数，能够使电机的保持力矩和自定位力矩达到最佳，对电子膨胀阀步进电机的研究和设计有借鉴价值。

An Improved Binary Wolf Pack Algorithm Based on Adaptive Step Length and Improved Update Strategy for 0-1 Knapsack Problems

Binary wolf pack algorithm (BWPA) is a kind of intelligence algorithm which can solve combination optimization problems in discrete spaces.Based on BWPA, an improved binary wolf pack algorithm (AIBWPA) can be proposed by adopting adaptive step length and improved update strategy of wolf pack. AIBWPA is applied to 10 classic 0-1 knapsack problems and compared with BWPA, DPSO, which proves that AIBWPA has higher optimization accuracy and better computational robustness. AIBWPA makes the parameters simple, protects the population diversity and enhances the global convergence.

基于S7-200 PLC的PID参数自整定方法

基于西门子S7-200 PLC的PID参数自整定功能及PID模拟量闭环控制器原理,结合工程实践,介绍了西门子S7-200 PLC在PID模拟量闭环控制器中的应用方法。论文分析了PID模拟量闭环控制器的控制特点及参数自整定规则,说明如何实现西门子S7-200 PLC的PID温度控制模块对PID模拟量闭环控制器的在线自整定和自调整,并通过V4.0版的编程软件STEP7-Micro/WIN进行实例仿真,介绍了S7-200 PLC的PID自整定参数的最优组合方法。

基于STEP和VC++的CAX系统集成技术研究

本文在详细阐述基于中性文件的CAX系统集成层次结构基础上,通过建立EXPRESS/中性文件/C++之间的数据类型映射、STEP-AP203实体/C++类/中性文件实体实例/C++类对象之间的映射、STEP-AP203实体/C++类继承关系映射,奠定了基于STEP和VC++的CAX系统集成的理论基础,并重点介绍了"词法分析模块"和"VC++对象定义模块"的实现方法。

太阳X-EUV成像望远镜波长选择装置

太阳X射线-极紫外射线（X-EUV,X rays-Extreme Ultraviolet）成像望远镜是我国专门服务于空间天气预报研究的太阳短波成像监测仪器,望远镜工作在0.4～10 nm的X射线波段和19.5 nm的极紫外谱段,能够提供全日面、高分辨率的成像观测.波长选择装置是该望远镜的一个重要子系统,可以增强望远镜动态响应范围,有助于获取更多的反演日冕等离子体参数,这些参数可用来诊断日冕活动.该装置的运动控制具有低功耗的特点,能够满足空间应用环境的特殊要求.其中,步进电机精位置控制是设计的重点,有2种光电编码矩阵可以用于位置检测,从工程可实现角度优选出其中一种,并且从工程可靠性角度分析了该光电编码矩阵的故障模式,提出了在轨故障处理的预案.