Initial rotor position estimation and sensorless direct torque control of surface-mounted permanent magnet synchronous motors considering saturation saliency

For a practical direct torque-controlled (DTC) permanent magnet synchronous motor (PMSM) drive system, the information of the initial rotor position, which is usually obtained by a mechanical position sensor, is essential for starting under the full load. To avoid the disadvantages of using mechanical position sensors, great efforts have been made on the development of sensorless control schemes. An initial rotor position estimation strategy is presented for a DTC PMSM drive based on a nonlinear model of PMSM incorporating both structural and saturation saliencies. In the new scheme, specially designed high-voltage pulses are applied to amplify the saturation saliencies. The peak currents corresponding to the voltage pulses are used, in combination with the inductance patterns, to determine the d-axis position and the polarity of the rotor. The presented initial rotor position identification strategy has been implemented in a sensorless DTC drive for a surface-mounted PMSM. Experiments are conducted to confirm the effectiveness of the method and the performance of the drive system. © The Institution of Engineering and Technology 2008

A general method for designing the transformer of flyback converters based on nonlinear FEA of electromagnetic field coupled with external circuit

This paper presents a general method for designing the transformer of flyback switching AC-DC converters based on nonlinear finite element analysis (FEA) of electromagnetic field coupled with external circuit. For that, the variation patterns of the PWM duty ratio and the current flowing through the windings of transformer versus the input voltage are introduced first, and then several important principles for the design of the transformer are given by using analytical method. As the magnetic saturation and control delay possess heavy influence on the safety of the operation, a MATLAB/Simulink based simulation model, in which both the nonlinear differential inductance and the control delay are included, is built to predict the converter transient performance. The nonlinear differential inductance is calculated by a general program of nonlinear 2-D FEA in Matlab/Simulink surrounding. By running the model, the performances of the converter with different loads and input voltages are obtained. Simulation results are in good agreement with theoretical analysis

Effects of armature reaction on the performance of a claw pole motor with soft magnetic composite stator by finite-element analysis

We investigated the effects of armature reaction on the performance of a three-phase three-stack claw pole motor with soft magnetic composite stator core by using three-dimensional finite-element analysis (FEA), which is an effective approach to accurately compute the parameters and performance such as the back electromotive force (EMF), core losses, and winding inductance at various saturation levels. The motor is rated as 500 W at 1800 rpm when the stator current is 4.1 A, driven by a sensorless brushless DC scheme. Because of the armature reaction, the back EMF produced by the rotor permanent magnets and the developed torque is reduced by about 3.3% at the rated load, and the core losses increase drastically by 41% from no-load to full-load. The winding inductance is computed with different loads at different rotor angles. © 2007 IEEE

Intelligent coordination steering control of automated guided vehicle

In this paper, based on the neural network, fuzzy control and bang-bang control, an intelligent coordination control strategy for automated guided vehicle (AGV) steering system is presented. The dynamic steering model of distance error and orientation angle error for AGV is expressed. With least square method of system identification, the model of AGV is identified. Because a toy type of AGV is employed, its structure is simple, but AGV model parameters are variable according to the operating conditions and environment. In order to improve the dynamic performances of AGV, the intelligent coordinated control strategy is used to design the AGV controller in the AGV steering control system. Simulation and experimental results show the effectiveness of the proposed control strategy. © 2011 IEEE

Accurate determination of parameters of a claw-pole motor with SMC stator core by finite-element magnetic-field analysis

Effective and accurate prediction of key motor parameters, such as winding flux, back electromotive force, inductance and core losses, is crucial for design of high-performance motors. Particularly, for electrical machines with new materials and nonconventional topology, traditional design approaches based on the equivalent magnetic circuit, empirical formulas and previous experiences cannot provide correct computation. The paper presents accurate determination of major parameters of a three-phase three-stack claw-pole permanent-magnet motor with a soft magnetic composite (SMC) stator core by finite-element analysis of the magnetic field. The effects of magnetic saturation and armature reaction are considered. The theoretical results by numerical analysis are validated by the experiments on the claw-pole SMC-motor prototype

A unified hybrid model with two level networks for peak current mode controlled buck-boost converters operating in DCM and CCM

Theis paper presents a unified hybrid model with two level networks for peak current mode controlled buck-boost converters operating in continuous conduction mode (CCM) and discontinuous conduction mode (DCM). It is a network model with two levels in which both a detailed switching model and a small signal average model are included correspondingly. The nonlinearity of some electronic components and the parasitical effects of circuit elements are considered. The nonlinear inductance is calculated by finite element analysis (FEA). The dynamical performance of the buck-boost converter can be obtained from the detailed switching model in the first level network, and then the frequency domain performance can be obtained from the average model in the second level network. As an automatic mechanism of exchanging data between two models is proposed, all the performances can be obtained automatically. By implementing the proposed model in Simulink surrounding, both the large signal transient performance and the frequency domain behavior of converters are obtained efficiently

Performance characteristics of an HTS linear synchronous motor with HTS bulk magnet secondary

A single-sided high-temperature superconducting (HTS) linear synchronous motor (HTSLSM) with an HTS bulk magnet array as its secondary has been developed, and a split pulse coil magnetization system is used to magnetize the secondary HTS bulks with alternating magnetic poles. The electromagnetic parameters of the HTSLSM have been calculated to verify its performance. The HTSLSM is incorporated with a developed control system based on the voltage space vector pulsewidth modulation strategy implemented by a computer-software-controlled platform. A compositive experimental testing system has also been developed to measure the thrust and normal force of the HTSLSM. The traits of the thrust and normal force have been comprehensively identified experimentally, and the results from the experiments and analysis would benefit the electromagnetic design and the control scheme development for the HTSLSM. © 2006 IEEE

A 3-D vector magnetization model with interaction field

This paper presents a vector model of magnetization based on the three-dimensional (3-D) Stoner-Wohlfarth elemental operator. To account for the magnetic interactions between particles, a phenomenological mean-field approximation is employed. The paper also illustrates the numerical simulation results of the magnetization in 3-D. This model will be useful to simulate the magnetization process of complicated topology flux electromagnetic devices. © 2005 IEEE

Comparative study of 3D flux electrical machines with soft magnetic composite cores

This paper compares two types of three-dimensional (3D) flux electrical machines with soft magnetic composite (SMC) cores, namely claw pole and transverse flux machines. 3D electromagnetic field analysis is conducted for the computation of some important parameters and optimization of the machine structures. An Equivalent electric circuit is derived to calculate the machine performances. The analysis methods are validated by experimental results of a single phase claw pole permanent magnet machine with a SMC core. Useful conclusions are drawn from the evaluation and comparison of two machines with soft magnetic composite cores