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For improved efficiency and torque performance, brushless DC (BLDC) motors require a phase advance circuit. In a conventional phase advance circuit, the induced voltage of the Hall sensor is assumed to be a sinusoidal wave. But the actual induced voltage of the Hall sensor includes other harmonic components which influence the real phase advance angle. Performance curves of phase advance angle versus frequency for a conventional circuit do not work well when the harmonic components are considered. We therefore propose an improved circuit in which the phase advance angle is more accurate than that of a conventional circuit when the harmonic components are considered. Furthermore, the proposed circuit provides better performance. We present experimental results to verify the related theoretical analysis. Index Terms--Automatic phase advance adjustment, single-phase BLDC motor.

In this paper, a new double-stator cup-rotor permanent-magnet brushless DC (PMBDC) machine is proposed and analyzed. Since the machine structure is so unique while its operating principle is so distinct, a numerical field approach, namely the circuit-field-torque grid-model time-stepping finite-element method (CFT-GM-TS-FEM), is newly developed to analyze the steady-state and dynamic characteristics of the machine. Particularly, the analysis of eddy-current loss in both the PMs and iron core of the machine is conducted. Experimental results are given for verification. Index Terms--Eddy-current loss, finite-element method, permanent-magnet machine.

This paper proposes a hybrid observer for sensorless control of permanent-magnet synchronous motor drives equipped with an inverter output LC filter. An adaptive full-order observer is augmented with a high-frequency signal injection method at low speeds. The only measured quantifies are the inverter phase currents and the dc-link voltage. The effects of the LC filter on the signal injection are investigated, and it is shown that the filter is not an obstacle to using signal injection methods. The proposed method allows sensorless operation in a wide speed range down to zero speed. Experimental results are given to confirm the effectiveness of the proposed method. Index Terms--Inverter output filter, permanent-magnet motors, sensorless control, signal injection.

The present and future market for motors places a high value on operating efficiency, reliability, variable-speed operation, low running temperature, quiet operation, and low cost. Permanent-magnet (PM) motors are now able to meet these market expectations across an increasing range of ratings. Compared to the prolific induction motor, PM motors provide the attributes of efficiency, reliability, etc. They also have the additional advantages of higher power density, superior power factor (low current), low rotor temperature, and synchronous operation. Advancement in magnet technologies allows operation at higher temperatures without permanent magnetization loss. The economic viability of PM motors is increasing with additional sources offering rare-earth magnets such as neodymium iron boron at lower prices. Performance comparisons between induction motors, surface PMs, and salient-pole PM motors are presented in this paper. Index Terms--Efficiency, motor, permanent magnet (PM).

A flexible approach to dynamically predict the performance of brush-commutation machines is presented. A circuit component called a commutator bar is introduced to model the relative position of a commutation segment to a brush, and a commutation model is introduced to model its characteristics. The circuit that describes the connection of all coils to all commutator bar components is coupled with transient finite element analysis. Simulated results at no-load and load operations are presented and compared with the measured data. Index Terms--Brush commutation, DC machine, field-circuit approach, transient finite element analysis.

A position control of a class of servomotors is addressed in this paper via a novel adaptive fuzzy PI sliding mode control. The premise and the consequence parts of the fuzzy rules are tuned with adaptive schemes. To attenuate chattering effectively, the discontinuous control is approximated by an adaptive PI control structure. Moreover, the bound of the discontinuous control term is assumed to be unknown, and an adaptive mechanism is used to estimate this bound. All adaptive laws are derived via Lyapanov synthesis method, thereby guaranteeing the dosed-loop stability. The proposed approach has the added advantage that, for external disturbances, it only requires a bound to exist, without needing to know the magnitude of this bound. The proposed controller is applied to control a model of uncertain induction servomotor subject to significant disturbances and a model of DC servomotor with unknown parameters and uncertainty in load condition. The analysis of simulations reveals the effectiveness of the proposed method in controlling servomotors in terms of significant reduction in chattering while maintaining asymptotic convergence. Index Terms--Adaptive control, DC motors, fuzzy systems, induction motors, sliding mode control (SMC).

In the search for better efficiency, an auxiliary energy system (AES) for electric vehicles (EVs) was designed, implemented, and tested. The system, which is composed of an ultracapacitor bank and a buck-boost converter, was installed in an EV, which is powered by a lead-acid battery pack and a 54-kW brushless dc motor. Two control strategies where developed: one based on heuristics and the other based on an optimization model using neural networks. These strategies were translated to algorithms and implemented in a digital signal processor, and their performance was evaluated in urban driving. The results were incorporated to an economic evaluation of the system, which shows that the reduction in costs would only justify the inclusion of this type of system in a lead-acid battery-powered vehicle if the battery life is extended by 50% or more, which is unlikely. The same results were extrapolated to a case in which the lead-acid batteries are replaced by a fuel cell. In this case, the costs of different power support systems were evaluated, such as ultracapacitors and high-specific-power lithium-based batteries. The results showed a significant cost reduction when AES configurations are included in contrast to a system powered by fuel cells only. Also, the cost reduction was higher when using ultracapacitors for this purpose. Index Terms--Energy management, energy storage, road vehicles, ultracapacitors.

In this paper, the influence of the stiffness and damping of real elastic shafts on the behavior of a multidrive system driving a tissue paper machine is investigated. The drive system consists of four dc motors, where two of them drive the Yankee drying cylinder and the other two drive the presses section. Six-pulse thyristor bridge power converters that are connected to the same power transformer supply the motors. The inertias of the motors and the driven machines, in conjunction with the shaft stiffness, form mechanical resonators. Thus, resonance phenomena may occur, which may lead to undesirable results. This particular case results to two three-mass and one five-mass systems. This paper presents an analysis of the resonance frequencies of two sections of the machine during startup and machine production, considering the shaft stiffness (shaft diameter, length, and thickness). The elastic shafts eliminate the ripple of the motor electromagnetic torque, which is transferred to the driven machine. The behavior of elastic shafts with different stiffness in the transmission system is studied. Moreover, the steady state and dynamic behavior of the system considering the influence of the elastic shafts and vibration analysis were investigated using simulation. A model algorithm for system simulation was developed using the MATLAB/SIMULINK software. Characteristic simulation results are presented and are expressed in terms of speed and torque response. Considering the resonance frequency analysis and simulation results, mechanical design guidelines can be given for the most significant drive components in order to avoid torsional oscillation resonance phenomena and minimize torsional oscillations of the drive system. Index Terms--Current and torque control, dc motor drives, modeling, pulp and paper industry, resonance, simulation, vibrations.

The Furuta pendulum consists of an arm rotating in the horizontal plane and a pendulum attached to its end. Rotation of the arm is controlled by a DC motor, while the pendulum is moving freely in the plane, orthogonal to the arm. Motivated, in particular, by possible applications for walking/running/balancing robots, we consider the Furuta pendulum as a system for which synchronized periodic motions of all the generalized coordinates are to be created and stabilized. The goal is to achieve, via appropriate feedback control action, orbitally exponentially stable oscillations of the pendulum of various shapes around its upright and downward positions, accompanied with oscillations of the arm. Our approach is based on the idea of stabilization of a particular virtual holonomic constraint imposed on the configuration coordinates, which has been theoretically developed recently. Here, we elaborate on the complete design procedure. The results are illustrated not only through numerical simulations but also through successful experimental tests. Index Terms--Furuta pendulum, motion planning for periodic orbits, orbital stability, virtual holonomic constraints.

We present the results of our resarch on the factors that cause thrust fluctuation in moving-magnet-type permanent-magnet brushless DC linear motors (PMBLDCLM). We combined Fourier transforms and finite-element models to obtain the power spectra of three components of the detent force. We developed a method of optimizing magnet width to minimize the detent force on the basis of harmonic analysis. To verify this method, we designed several motor models with different magnet widths and analyzed them by finite-element methods. The calculations and experimental results prove that thrust fluctuation of the motor can be effectively reduced with our method. Index Terms--Detent force, edge effect, harmonic analysis, PMBLDCLM, thrust fluctuation.

The transient simulation of a magnetic machine often requires simulating much more than one period in order to obtain the periodic steady-state behavior. This paper presents a method to bypass this start-up transient in order to arrive quickly at the desired steady-state waveform, using a time-domain approach. The method formulated in this paper applies to balanced three-phase devices, but is limited to devices in which the eddy currents do not contribute significantly to the startup transient. Thus, the method is particularly suited to brushless DC motors and synchronous machines. Index Terms--Brushless rotating machines, harmonic analysis, periodic steady state, permanent magnet machines, rotating machine transient analysis, synchronous generator transient analysis.

Efficient linear solvers for mortar finite-element method are studied. An analysis of a brushless DC motor shows that proposed pre-conditioners improve the convergence to the solutions of linear systems with and without Lagrange multipliers. Index Terms--Lagrange multiplier, motor analysis, mortar finite-element method (FEM), preconditioner.

The analytical method of images using magnetic charge is applied to analyze characteristics of the slotless axial-flux type brushless dc motors in this paper. The theory of analytical method is introduced and flux density distribution is calculated and verified by three-dimensional finite element analysis. Then, characteristics between single and dual gap axial-flux motor are analyzed and compared. Index Terms--Axial-flux, BLDC, dual gap, image method, magnetic charge, single gap, slotless.

The numerical analysis of electromagnetic devices can generate large volumes of data describing the performance of the device. To date, this information has been provided to the user either as sets of numeric data or in graphical form. However, modern personal computers are actually capable of producing other forms of output. Among these are force feedback and sound systems. These are common in computer gaming but have not been explored in any depth in scientific result evaluation. This paper investigates the possible benefits in result understanding which may accrue from using these systems. Index Terms--Computational electromagnetics, force-feedback, result presentation, sonification.

This paper presents a procedure for increasing the daily output mechanical energy supplied by dc motors directly connected to solar cell arrays (SCA). The technique is based on the use of dc motors with two components of magnetic field: a constant component that can be provided by a permanent magnet (or a separately excited winding) and a second one produced by a series field winding. It will be shown that through properly selecting the parameters of the motor's magnetic circuit, (i.e., the value of the constant field and the mutual inductance as well as their relative directions), an improved matching between the PV-array and the dc motor can be achieved. Based on assessing and minimizing an expression used to quantify the power mismatch between the SCA and the dc motor, the optimal parameters will be identified. A comparison will then be made between this suggested motor design and both the separately excited and series motors. Index Terms--DC motors, matching, modeling and simulation, optimal design, photovoltaic systems.

This paper describes the effect of eddy currents generated in the rotor steel shell of exterior - rotor type permanent magnet brushless DC motor of which the rotor is revolving at a high speed. A two dimensional time-stepped finite element method is used to analyze an electromagnetic field and compute motor performance. The conductivity of the rotor steel shell is modified to consider the transverse edge effect. As a result, the effect of eddy currents is shown by comparing the analysis results between when the proposed method is used and when the method is not used. Index Terms - Brushless DC motor, eddy currents. finite element methods, permanent magnets.

The aim of this work is to determine the optimal design parameter for reduced arc characteristics of the high-voltage direct current (dc) motor due to the increase of the terminal voltage from 14 to 42 V. The main interesting focus is whether the reactance voltage decreases according to kinds of the brush, the magnet and the electroangle of the stator magnet. To limit the coil inductance, the electrographite instead of the metal graphite is applied to the electromagnetic design for the 42-V dc motor as automotive application. Supposing the law of energy conservation during the commutation period, the resistivity of the eletrographite with high value makes the inductance of the rotor coil with low value. As a result, the arc appearance decreases remarkably. It is applicable to the automotive application such as cooling fan for engine with the continuous high current of the 42-V power net. As an extra approach, the elecromagnetic design is optimized with the same models to make low coil inductance upon similar required load. Finally, we verify the appearance of the arc reduction through comparing a few photographs, which show how these approaches play a role as a bridge from 14 to 42 V. Index Terms--Automotive, arc reduction, direct current (dc) motor, targetwise parameter optimization (TPO), 42 V.

Byline: Liangtoa Zhu, Ravi Patankar An approximate motor inverse model is usually employed to achieve torque control of a brushless DC motor. Variations of motor parameters directly impart inaccuracies in the motor inverse model, thus the performance of the system suffers. A multi-parameter estimation method based on Gram-Schmidt Orthonormalization in a continuous function space of feedback signal is proposed in this paper. The stability of the estimation scheme is proved. Performance improvement of the estimation scheme is discussed. Comparison of simulations for closed loop voltage control of an electric power steering system actuator confirms a lower bound of error of the estimated parameter and faster adaptation with the proposed improvements for the estimation scheme.