On-line mechanical unbalance estimation for permanent magnet synchronous machine drives

An on-line mechanical unbalance estimation for permanent magnet synchronous machine (PMSM) drives is presented. At high speeds, either rotor or mechanical load unbalance generates vibration that can cause mechanical failure such as a defect of a bearing or shaft. To prevent failure and minimise mechanical vibration, the amount of the rotating unbalance should be detected in real time. The information of the estimated unbalance can be utilised to manage an operation to achieve the durability of mechanical parts. The dynamic nature of a mechanical system with a PMSM with regard to unbalance is investigated. From this examination, the models of the stator current in time and frequency domains for PMSMs are presented to develop a robust real-time unbalance estimation scheme. Based on the modelling and analysis of a rotating mechanical system using a PMSM drive, a compact unbalance estimation algorithm is proposed. The algorithm is combined with an open-loop torque observer and an unbalance estimator using a filter. Experimental results show the validation of the developed model and the proposed on-line unbalance estimation scheme.     

Design,analysis and fabrication of a linear permanent magnet synchronous machine

This paper deals with the design, analysis and fabrication of a 320 W, 5 m/s, 4-pole permanent-magnet-based linear synchronous machine (LPMSM). The design deals with conventional hand calculations followed by design fine-tuning and analysis using standard FEM packages. Fabrication of the machine has been also done at the works of a local small machine manufacturer after procurement of imported permanent magnets (PMs). The work presented here focuses on design and fabrication of LPMSM linor stampings with fixed dimensions and standard available PM tablets with a view to providing simple design guidelines. This prototype forms part of a variable speed linear motor drive that is being developed. The approach presented here might provide new ideas to those researchers who may not have the capability to bear cost of fabrication of lamination and PMs from scratch but would like to manufacture LPMSMs from available stampings and tablet PMs. Additionally, it may serve as a base document for the R&D personnel in this area.     

Selection of the parameters of a permanent magnet synchronous machine by using nonlinear optimisation

The selection of the parameters of a permanent magnet synchronous machine (PMSM) is analysed using nonlinear optimisation. The constraints of the optimisation can be set to take the control principle into account. Compared with previously presented analyses, constant flux-based control as well as an absolute maximum criterion where no constraints are made to the control principle is analysed. Moreover, the requirements of the application are easily incorporated into the presented optimisation as additional constraints. On the basis of the results, the parameters of the PMSM (permanent magnet's flux linkage and the direct and quadrature axis inductances) can be selected. The results show that when using a constant flux linkage-based control principle (e.g. direct-torque control) more torque can be obtained compared with minimum current vector control. After analysing the effect of different parameters, a design procedure is suggested and an interactive design programme is implemented with Matlab     

Dynamic performance of a vector-controlled five-phase synchronous reluctance motor drive: an experimental investigation

Multi-phase ac motor drives are nowadays considered for various applications due to numerous advantages that they offer when compared with their three-phase counterparts. In principle, control methods for multi-phase machines are the same as for three-phase machines. The operation of an indirect vectorcontrolled five-phase synchronous reluctance machine with current control in the stationary reference frame is analysed. Performance, obtainable with ramp-comparison current control, is illustrated for a number of operating conditions on the basis of experimental results. Full decoupling of rotor flux control and torque control is realised. Excellent dynamic response is achieved during acceleration, deceleration and reversing transients of machine.     

Estimation of rotor and load angle of direct-torque-controlled permanent magnet synchronous machine drive

A dynamically well performing rotor and load angle estimation method for direct-torque-controlled (DTC) permanent magnet synchronous machines drives is presented. The rotor or load angle is needed as example in the limitation of the load angle. The method uses the same flux linkage estimate that is used in the core of the DTC and calculates the load and rotor angle directly from the motor equations. The effect of the flux linkage estimation method is analysed through simulation. Both the steady-state and dynamical measurement results are also provided, showing the good performance of the suggested method. The performance is adequate to be used as example in the limitation of the load angle in order to prevent the machine falling from synchronism     

Four-quadrant instantaneous torque control of switched reluctance machine at low speed based on co-energy control

An instantaneous torque control scheme of switched reluctance machines for four-quadrant operation at low speed based on co-energy considerations is presented. The co-energy is estimated online with a co-energy estimator, which only requires easily obtainable parameters such as the machine terminal quantities and the machine characteristics at low current. By regulating the co-energy while tracking a one-dimensional co-energy profile, the torque contribution of each phase of the switched reluctance machine can be controlled and optimised. Thus, the requirement of pre-measured data is reduced when compared to current-profiling methods. The closed-loop control system is analysed and then designed based on internal model control. The excitation sequence and torque sharing function for four-quadrant operation to produce smooth torque output are also presented. The operation limits of the scheme are examined. Computer simulation and experimental results confirm that the proposed scheme can be exploited to reduce the high-frequency torque ripples significantly.     

Adaptive controller design for a synchronous reluctance motor drive system with direct torque control

The design and implementation of adaptive controllers for a sensorless synchronous reluctance drive system with direct torque control is proposed. Two adaptive control algorithms, which include adaptive backstepping control and model-reference adaptive control, are proposed to improve the performance of a sensorless direct torque control synchronous reluctance motor drive system. A digital signal processor, TMS320-C30, is used to execute the rotor position estimating technique and the adaptive control algorithms. The system shows good transient responses, good load disturbance responses and good tracking responses. Several experimental results validate the theoretical analysis. The advanced controller design for a sensorless synchronous reluctance motor drive with direct torque control is proposed.     

Incorporating control trajectories with the direct torque control scheme of interior permanent magnet synchronous motor drive

Interior permanent magnet (IPM) synchronous machines have gained increased attention for applications in electric vehicle, variable speed wind turbine, industrial drives, etc., because of their high torque density, wider speed range and compact construction. The authors present a detailed analysis and modelling of control trajectories and incorporate those trajectories in the direct torque control (DTC) scheme of an IPM synchronous motor drive, for constant-torque and constant-power operating regions. The control trajectories are implemented on a real-time digital signal processor. Because the inputs to the inner torque control loop of DTC are the references for the torque and the amplitude of the stator flux linkage (λ_s), they are transformed in the T-λ_s plane, than in the i_d - i_q plane in the indirect control. The modelling and experimental results are presented. Results show very good dynamic and steady-state performances of direct torque controller, incorporating these control trajectories.     

Full speed range permanent magnet synchronous motor control without mechanical sensors

This study presents a control method for permanent magnet (PM) motors based on a combination of a non-linear full-order observer and a signal injection scheme. Stable mechanical-sensorless operating range down to zero speed at full load is obtained using only voltage and current sensors. The signal injection scheme uses the asymmetry of the motor?s d and q-axis inductances to estimate rotor position and speed. Such asymmetry is also taken into account in the motor model used to construct the observer to reduce current estimation error. The performance of the proposed scheme is validated through experimental results.     

永磁同步电动机恒磁链控制特性分析

在永磁同步电机数学模型的基础上,根据电机全磁链ψ0和转子永磁体与定子交链的磁链ψf相等的原则,介绍了恒磁链控制法.并通过推导永磁同步电机电磁转矩与定子电流的数学方程,采用查表法建立电流与转矩的拟合关系,使用MATLAB仿真软件建立电机模型,并将恒磁链控制分别与id=0和最大转矩电流比(MTPA)控制方法做了详细对比.仿真结果表明,恒磁链控制法下系统的稳态误差仅有0.478%,稳定性很优秀,且调整时间分别比id=0控制和MTPA控制要快7.7%和27.6%,且功率因数为0.72,均高于id=0控制的0.62和最大转矩电流比控制的0.67.     

The evolution of the synchronous machine

The author discusses the beginnings of the synchronous machine at the end of the 19th century. In particular the author discusses the first long-distance transmission of high voltage three phase power using a machine with a power output of 210 kW at the International Exposition at Frankfurt in 1891. This machine is described in detail. Milestone in the development of the synchronous machine and hydroelectric generators are discussed     

永磁直线同步电机矢量控制系统建模与实现

针对永磁直线同步电机（PMLSM）的特点，建立PMLSM在dq两相坐标系下的数学模型。介绍了永磁直线同步电机矢量控制系统并给出了硬件和软件的设计思想。通过对控制电流以及电机位置的实验分析，验证了所研究的基于矢量控制的永磁直线同步电机矢量控制方法的有效性。     

A novel synchronous permanent magnet planar motor and its model for control applications

A novel synchronous permanent magnet planar motor (SPMPM) with iron core is proposed. It has higher continuous force compared to the coreless SPMPM. In the novel SPMPM, two sets of windings for generating x-direction thrust and y-direction thrust are perpendicularly fixed in the x-direction slots and y-direction slots of a mover core, respectively. For control system development applications, an electromagnetic model is derived and the analytical method for calculating the model parameters is also reported. The model describes an important characteristic of the novel SPMPM that the x-direction thrust and y-direction thrust are independent of each other. To verify the model and the parameter calculation method, the finite element method (FEM) is used for calculating the phase inductances and electromagnetic forces of an example SPMPM. The results from FEM are in good agreement with the results from the analytical equations. It demonstrates the feasibility and credibility of the proposed model and parameter calculation method to a certain extent.     

基于参数辨识的永磁同步电机自校正速度控制方法

针对永磁同步电机伺服系统的机械参数经常发生变化的情况,提出了一种通过辨识转动惯量和摩擦系数实现速度控制器系数自校正的方法.辨识转动惯量和摩擦系数采用的是根据波波夫超稳定理论设计的一种转动惯量和摩擦系数的模型参考辨识算法.辨识中引入了负载转矩观测器的观测值,使辨识算法不需要附加条件.参数辨识的结果用于速度控制器的校正.通过实验分析了速度环采用比例积分(PI)控制器时控制器的系数不等于理论计算值的问题,得出了一种简单的控制器系数自校正规律--比例系数和转动惯量成正比,且积分系数和摩擦系数也成正比.这种方法能够根据机械参数的变化校正控制器,提高速度控制的性能.仿真结果证明了参数辨识方法和控制器系数校正规律的有效性.     

Single sensor current control of permanent magnet synchronous motor using field programmable gate array

An innovative current control scheme for a permanent magnet synchronous motor using a single current sensor placed at a low potential, in the DC return line of the inverter is proposed. The feedback mechanism employs a digital asymptotic sinusoidal curve-fitting observer implemented in a single field programmable gate array chip. The observer, activated by firing pulses, reconstructs the three-phase feedback signals. The asymptotic observer does not require the parameters of the motor or the load and it is robust under dynamic conditions. The development of the algorithm, implementation and experimental verification of the proposed control scheme are presented in detail     

Fields in permanent magnet linear synchronous machines

The determination of electromagnetic fields in permanent magnet linear synchronous machines (PMLSM's) to form the basis for the evaluation of forces and parameters of PMLSM'S (to be presented in a subsequent paper) is discussed. Analytical techniques applied to permanent magnet rotary synchronous machines are modified and adapted to PMLSM's. Fields are determined analytically in a single-sided PMLSM, and computed results by the finite-element method are compared with those obtained experimentally. A good correlation between the results obtained by the three procedures-analytical, finite-element computational, and experimental-validates the approximations used in the analysis.     

Improvement in the field-weakening performance of switched reluctance machine with continuous mode

A new operation mode for switched reluctance motors (SRMs), called 'continuous mode', is described. By using this mode, the torque and then power in field-weakening mode can be considerably increased without any hardware modifications. Consequently, power and torque densities of SRMs become comparable to other technologies (synchronous and induction motors) and with a field weakening operation over a large speed range. This new degree of freedom makes it possible to improve the motor design, by modifying the rotor pole arc size or the windings turns per pole. Only simulation results are presented here, for a 12/8 SRM. Results confirm that the maximum power is improved (constant power on a very large speed range) and with a higher efficiency than that in the classical discontinuous mode.     

改进滑模变结构永磁电机控制器研发

为克服传统滑模观测器对永磁同步电机进行无传感器控制时存在高频抖振和转子位置估算不精确的缺陷,提出一种基于改进滑模观测器的PMSM控制器设计方法.首先,建立PMSM的数学模型并分析传统滑模观测器转子位置估计原理和缺陷,然后,采用低通滤波器对电流误差开关信号进行滤波并对转角进行补偿,采用饱和函数代替开关函数以减少滑模运动的高频抖动,最后,采用李亚普若夫稳态判定方程证明设计的改进观测器的稳定性.系统测试表明:该方法能较为准确地对PMSM的转子位置和速度进行估算,具有较高的估算精度.     

Position sensorless control for interior permanent magnet synchronous motor using adaptive flux observer with inductance identification

A position sensorless control of interior permanent magnet synchronous motors (IPMSMs) is proposed using the adaptive full-order observer with inductance identification. First, mathematical models are discussed for robustness improvement to inductance variation and inductance identification in IPMSMs, the models show that a high-frequency signal needs to be injected to identify the inductance. Next, novel adaptive schemes for inductance identification are proposed here. Finally, identification experiments under IPMSM position sensorless control are carried out with the proposed methods, in which the feasibility and effectiveness of the methods are shown in terms of inductance identification performance and the convergence of position estimation error.