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Abstract

In this paper the mathematical model of the brushless DC motor (BLDCM) with a double 3-phase stator winding is analysed. Both the 3-phase windings are mutually displaced by 30 electrical degree. Special care has been sacrificed to influence of higher harmonics of induced electromotive forces (EMF) on electromagnetic torque and zero sequence voltages that may be used for sensorless control. The mathematical model has been presented in natural variables and, after transformation to symmetrical components, in a vector form. This allows, from one side, for formulating the equivalent circuit suitable for circuit oriented simulators (e.g.: Spice, SimPowerSystems of Simulink) and, from the other point of view, for analysis of higher harmonics influence on control possibilities. These considerations have been illustrated with some results of four quadrant operation obtainded due to simulation at automatic control.
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Abstract

The paper presents an algorithm and software for the optimal design of permanent magnet brushless DC motors. Such motors are powered by DC voltage sources via semiconductor switches connected to the motor phase belts. The software is adjusted to the design of motors with NdFeB high energy density magnets. An attention has been given to issues important in the design of the motors, i.e., permanent magnet selection, structure of magnetic circuit, and armature windings. Particularly, precision of calculation of the permanent magnet operating point, visualization of selection process of the winding belts, and magnetic circuit dimensioning have been investigated. The authors have been trying to make the equations more specific and accurate than those presented in the literature. The user software interface allows changes in the magnetic circuit dimensions, and in the winding parameters. It is possible to examine simultaneously the influence of these changes on the calculation results. The software operates both with standard and inverted (outer rotor) motor structure. To perform optimization, a non-deterministic method based on the evolution strategy (ž + λ) - ES has been used.
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Abstract

Brushless DC motors are often used as the power sources for modern ship electric propulsion systems. Due to the electromagnetic torque ripple of the motor, the traditional control method reduces the drive performance of the motor under load changes. Aiming at the problem of the torque ripple of the DC brushless motor during a non- commutation period, this paper analysis the reasons for the torque ripple caused by pulse- width modulation (PWM), and proposes a PWM_ON_PWM method to suppress the torque ripple of the DC brushless motor. Based on the mathematical model of a DC brushless motor, this method adopts a double closed-loop control method based on fuzzy control to suppress the torque ripple of the DC brushless motor. The fuzzy control technology is integrated into the parameter tuning process of the proportional–integral–derivative (PID) controller to effectively improve the stability of the motor control system. Under the Matlab/Simulink platform, the response performance of different PID control methods and the torque characteristics of different PWM modulation methods are simulated and compared. The results show that the fuzzy adaptive PID control method has good dynamic response performance. It is verified that the PWM_ON_PWM modulation method can effectively suppress the torque ripple of the motor during non-commutation period, improve the stability of the double closed-loop control system and meet the driving performance of the motor under different load conditions.
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