基于转矩逆模型的SRM转矩脉动抑制研究

开关磁阻电机转矩逆模型的精度对于采用电流控制方式实现转矩控制的系统有很大的影响,文中采用经细菌群体趋药性算法优化后的最小二乘支持向量机建立开关磁阻电机的转矩逆模型,获得电流-转矩-角度特性;进而结合转矩分配函数和电流控制环构SRM转矩控制系统。通过仿真实验表明,该转矩逆模型准确地反映了电机的电流-转矩-角度特性,提高了开关磁阻电机控制系统中电流控制环的精度,并对该系统转矩脉动的抑制有重要作用。     

Performance evaluation for a limited-angle torque motor

Describes the performance evaluation of a limited-angle torque motor, using a simple piecewise analytical approach to overcome system nonlinearities. A block-diagram model developed from a combination of measurement and manufacturer's data is shown to be capable of accurately predicting both the steady-state and the dynamic performance. The approach described is of valuable assistance in the design of a complex multiloop nonlinear controller that is needed for a drive system containing the motor     

Probabilistic voltage harmonic analysis of direct torque controlled induction motor drives

In high frequency motor-drives such as direct torque controlled (DTC) induction motor drives, the motor harmonic loss, and electromagnetic interference are largely affected by the spectrum of the motor input voltage. Nonlinear elements in the control loop of DTC drive make harmonic analysis of the drive very complex compared to classical pulsewidth modulated controlled drives. In this paper, a probabilistic method to study the harmonic contents of voltage in DTC of induction motors is presented. The DTC voltage chain is simulated with a random process. Then, the autocorrelation function of voltage vectors is calculated and its power spectrum density is obtained. The effect of flux and torque hysteresis controller bands, machine parameters, and inverter dc-link voltage on the motor voltage spectrum is investigated. Major harmonics in the DTC voltage spectrum are specified and their behaviors are described. Simulation and experimental results are presented to justify the theoretical analysis.     

Control of switched reluctance motor torque for force controlapplications

The paper presents a method for controlling switched reluctance motor (SRM) torque for force control applications. SRMs are used in AdeptOne robots, and the authors perform experiments with two robots, controlled in coordination, in grasping and manipulation of various objects. The object and robot parameters are not exactly known, and adaptive methods are used to control the overall system. These methods are model-based control techniques which require high bandwidth torque control. This requirement is typical for high precision mechanisms. SRM characteristics are very nonlinear. In particular the torque ripple, friction, and the torque versus position and current relationships were analyzed in the context mentioned above, and specifically, for force control applications. The proposed method is based on a new commutation algorithm and a measured torque versus position and current relationship, used to smooth the SRM's torque ripple, hence generating a torque output nearly independent of position. Furthermore, the internal friction is estimated on-line, and compensated for. This renders a high accuracy torque tracking. The torque control method is based on feedback from the motor angular velocity, motor angle, armature current, and feedforward for friction compensation and cancellation of nonlinear effects. The method has been tested experimentally on Adept motors and the results were very encouraging. The method has been also used for adaptive control of two coordinated Adept robots     

Band-constrained technique for direct torque control of induction motor

In this paper, a novel technique for the direct torque control (DTC) of an induction motor is proposed, which overcomes the trouble of high torque ripple afflicting the conventional DTC technique. With the novel technique, the inverter voltage vector selected from the switching table is applied for the time interval needed by the torque to reach the upper (or the lower) limit of the band, where the time interval is calculated from a suitable modeling of the torque dynamics. By this approach, the control system emulates the operation of a torque hysteresis controller of analog type since the application time of the inverter voltage vector is dictated by the allowed torque excursion and not by the sampling period. It is shown by experimental results that the technique yields a considerable reduction of the torque ripple. A further and ultimate reduction is obtained by compensating for the delay inherent in the discrete-time operation of the control system. The outcome is that the torque ripple of the motor is constrained within the hysteresis band of the torque controller, for a band of customary value. An ancillary merit of the technique is the almost full elimination of the average torque error inherent in the conventional technique. If the hysteresis band is shrunk, the torque ripple is bound to swing out the band limits. Under this circumstance, an extension of the technique is developed, which helps keep the torque ripple at minimum. To assess the characteristics of the proposed DTC technique, the following quantities: average torque error, rms value of the torque ripple, and inverter switching frequency are measured for different stator flux angular speeds and hysteresis bands of the torque and flux controllers. As a comparison, the same quantities are given for the conventional DTC technique.     

在线转矩分配函数控制开关磁阻电机策略分析

开关磁阻电机(SRM)因双凸极结构,其内部磁场非线性导致运行过程中会产生较大的噪声和转矩脉动。根据开关磁阻电机数学模型,以四相8/6极SRM作为研究对象,用Matlab/Simulink搭建基于在线TSF策略的转矩脉动控制系统模型。系统将实时转矩跟踪参考转矩,将不确定性因素进行整体逼近减小误差,实现在线TSF控制。仿真结果表明,所提系统建模方法能有效地抑制转矩脉动,并增加其稳定性,为实际电机控制系统的设计提供新的思路及参考依据。     

基于Saber的异步电动机直接转矩控制系统仿真

为了验证基于三电平逆变器异步电动机直接转矩控制系统的可行性和有效性,利用Saber仿真软件优良的模块化和分级式的系统仿真能力,建立了异步电动机直接转矩控制系统中定子磁链与电磁转矩观测器、扇区判断、空间电压开关矢量表以及二极管箝位型三电平逆变器等子系统的仿真模型,并根据直接转矩控制原理最终构建了完整的系统仿真模型。利用所构建的系统仿真模型进行了仿真实验,仿真分析结果证明建立的系统模型是有效的,表明直接转矩控制系统具有良好的动态响应性能。     

动压陀螺马达力矩测量系统的设计

以工控机、马达力矩测量平台、数据采集卡为核心,设计了一种新型动压陀螺马达力矩测量系统,能够实时动态地对加速度计(陀螺)动压马达启动时的静摩擦转矩及运转时动摩擦转矩进行精确测量。同时,基于LabVIEW软件平台完成了系统软件设计,实现了动压陀螺马达力矩、转速、电流、电压等数据的实时采集及实时曲线显示。该系统可实现对马达性能的实时监控,完成无人值守的自动化测试。     

无轴承异步电机新型直接转矩控制研究

针对无轴承异步电机(Bearingless Induction Motor,BIM)传统直接转矩控制中转矩脉动大,悬浮性能不佳等问题,提出了一种基于滑模变结构的直接转矩控制方法 (SMVS-DTC)。首先根据转矩误差和磁链误差构造出相应的滑模切换面,然后采用指数趋近律设计了直接转矩控制器。在此基础上对所提方法进行了仿真和实验研究。仿真和实验结果表明,该方法有效地减小了转矩脉动和磁链脉动,并且提高了BIM转速动态响应和稳定悬浮性能。     

Nonlinear sliding-mode torque control with adaptive backsteppingapproach for induction motor drive

In this paper, the nonlinear sliding-mode torque and flux control combined with the adaptive backstepping approach for an induction motor drive is proposed. Based on the state-coordinates transformed model representing the torque and flux magnitude dynamics, the nonlinear sliding-mode control is designed to track a linear reference model. Furthermore, the adaptive backstepping control approach is utilized to obtain the robustness for mismatched parameter uncertainties. With the proposed control of torque and flux amplitude, the controlled induction motor drive possesses the advantages of good transient performance and robustness to parametric uncertainties, and the transient dynamics of the induction motor drive can be regulated through the design of a linear reference model which has the desired dynamic behaviors for the drive system. Finally, some experimental results are demonstrated to validate the proposed controllers     

New hybrid fuzzy controller for direct torque control induction motor drives

A new hybrid fuzzy controller for direct torque control (DTC) induction motor drives is presented in this paper. The newly developed hybrid fuzzy control law consists of proportional-integral (PI) control at steady state, PI-type fuzzy logic control at transient state, and a simple switching mechanism between steady and transient states, to achieve satisfied performance under steady and transient conditions. The features of the presented new hybrid fuzzy controller are highlighted by comparing the performance of various control approaches, including PI control, PI-type fuzzy logic control (FLC), proportional-derivative (PD) type FLC, and combination of PD-type FLC and I control, for DTC-based induction motor drives. The pros and cons of these controllers are demonstrated by intensive experimental results. It is shown that the presented induction motor drive is with fast tracking capability, less steady state error, and robust to load disturbance while not resorting to complicated control method or adaptive tuning mechanism. Experimental results derived from a test system are presented confirming the above-mentioned claims.     

Discussion on “An effective method for rotor resistanceidentification for high-performance induction motor vectorcontrol” [and reply]

In the original paper (Chan et al., see ibid. vol. 37, p. 477-82, 1990), the authors presented results based on the machine parameters of a 1 kW, four-pole induction motor listed in the Appendix. Here, the author discusses what he feels is some confusion regarding the inductance terms and their values. His comments and the original authors' reply are presented     

Real-time IP position controller design with torque feedforwardcontrol for PM synchronous motor

A digital signal processor (DSP)-based permanent magnet (PM) synchronous motor (SM) drive with a proposed recursive least-square (RLS) estimator and real-time integral-proportional (IP) position controller is introduced in this study. First, the rotor inertia constant, the damping constant, and the disturbed load torque of the synchronous motor are estimated by the proposed RLS estimator, which is composed of an RLS estimator and a torque observer. Next, the IP position controller is real-time designed according to the estimated rotor parameters, to match the time-domain command tracking specifications. Then, the observed disturbance torque is fed forward, to increase the robustness of the synchronous motor drive     

Development and testing of the torque control for the permanent-magnet synchronous motor

Hybrid electrical vehicles and electrical vehicles are being actively developed. A hybrid electric vehicle motor design requires high efficiency, high power/weight ratio, and reliability from low rotor speed to high rotor speed. The permanent-magnet synchronous motor is used in order to fulfill these requirements. The purpose of this paper is to develop a permanent-magnet synchronous motor control method for all rotor speeds. This method increases the torque and the efficiency at high speed when compared to the ordinary current error feedback method. A method composed of two compensators is proposed to achieve this objective. One of the compensators controls the torque using the voltage phases. The other one is the ordinary current error feedback. Several correcting methods for the voltage phase compensator have been proposed for the compensator for many control demands. The validity of the proposed method was confirmed using simulation and experimental evaluations.     

A low-cost sensorless technique for load torque estimation in ahybrid stepping motor

This paper presents a method of torque measurement in a hybrid stepping motor without the use of speed or position sensors. It is shown that torque ripple can be minimized by appropriate shaping of the phase-current pulses and that efficiency can be maximized when the level of mechanical load applied to the shaft is known. A controller is described which generates a signal related to the mechanical load by observation of the phase-current profile using a novel low-complexity technique. Practical results are presented, showing the torque estimation relative to measured torque     

A maximum torque control with a controlled capacitor for asingle-phase induction motor

This paper presents a new method to achieve a maximum torque for a single-phase induction motor. An AC adjustable capacitor using an electronic switch in parallel with a capacitor is proposed. The capacitor is short-circuited in a different period by an electronic switch during each cycle to vary the effective value of the AC capacitor. Two new optimization algorithms, which obtain a maximum starting torque by adjusting the effective capacitor, are proposed. No starting capacitor or centrifugal switch is used here. A theoretical analysis, and simulated and experimental results are presented in this paper     

A theoretical analysis of the “let-go” phenomenon

A mathematical analysis is presented that provides a theoretical explanation for the “let-go” neuromuscular stimulation phenomenon. This analysis includes consideration of electrophysiological, bioelectrical, and anthropometric factors that are involved in accidental electrical stimulation of forearm musculature during “let-go”     

An “add-on” analysis of large open circular-cylindricalcavities

The add-on method utilizes previously acquired solutions for sub-problems, comprising portions of a scatterer, as a part of the analysis. The process of adding the remainder of the solution is a relatively efficient one, assuming that the initial stage of the sub-problem has been performed. The “add on” method is based on two basic principles: A. Superposition is used to break up the unknown current into two components, the first one being a readily computable solution to a simple short circuited problem, and the second one is excited by a current source over the aperture area, and is the only one requiring computation. B. A gradual algorithm is used for the computation of the second current component for many sub-problems. Principle A leads to a purely algebraic algorithm of principle B, with no integral operators. In this work, this formulation is extended to the cylindrical case. In this ease, the aperture region is a portion of a circle complementing the circular conducting shell, thus it shrinks as the conductor increases in size and no truncation is needed. The short circuit current for the closed circular cylinder is computed rapidly using the FFT. The cylindrical problem is solved for large cylinders in three ways: (1) a direct Moment Method solution, (2) a direct spatial decomposition solution based on the MoM matrix and invoking the matrix partitioning technique, and (3) the cylindrical add-on scheme. All solutions are identical, however, the computational advantage of the add-on technique is quite apparent, as seen from the analysis of the operation count as well as from numerical examples     

A method for suppressing torque ripple of an AC motor by currentamplitude control

The authors examine a thyristor motor torque ripple suppression method that is simple in configuration. A simplified method of calculating motor torque ripple is introduced. This method enables calculation of velocity fluctuation due to torque ripple in the vicinity of the resonant frequency. Calculation results show that operation around the resonant frequency constitutes a problem. The current amplitude control method is effective for suppressing the torque ripple at the resonant frequency. This method detects the velocity fluctuation component and controls the current amplitude to eliminate that component. The velocity fluctuation component is detectable by using a filter that has a differential element. In addition, it is shown that the characteristic of the control system can be calculated with the aid of a Bode diagram, and its effectiveness is confirmed through simulation. From simulation results, this suppression method is found to be effective in reducing the velocity fluctuation to a practical level     

基于Buck-Boost的无刷直流电机换相转矩脉动抑制研究

针对永磁无刷直流电机存在的传统换相时转矩脉动大的问题,提出基于Buck-Boost变换器抑制无刷直流电机换相转矩脉动的方法。首先分析换相转矩脉动产生的原因,然后给出了在电机三相逆变器前加Buck-Boost变换器的拓扑电路图及调整直流母线电压的原理,从而达到换相的关断相与开通相的电流变化速率相同、抑制换相转矩的目的。通过Simulink进行仿真,仿真结果表明,该方法能够有效抑制永磁无刷直流电机换相转矩脉动。