• Journal of Electrical Engineering and Technology
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• v.7 no.6
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• pp.905-910
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• 2012

This paper reports an investigation of pulse width modulation (PWM) techniques for twophase brushless DC (BLDC) motors fed by a two-phase eight-switch inverter in a fan application. The three-phase BLDC motor is widely applied in industry; however, a lower-cost two-phase BLDC motor and drive circuit has been greatly in demand in recent years. In this paper, we introduce a mathematical model of the two-phase BLDC motor with sinusoidal back electromotive forces (EMFs) based on traditional three-phase BLDC motors. To simplify the drive algorithm and speed up its application, we analyze the principle of block commutation for a two-phase BLDC motor drive in the 180-electricaldegree conduction mode, and we further propose five PWM schemes to improve the commutation performance of the two-phase BLDC drive. The effectiveness of the proposed PWM methods is verified through experiments.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.932-941
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• 2014

In this paper, a simulation model for 7-phase BLDC motor drives for an Autonomous Underwater Vehicles (AUV) is proposed. A 7-phase BLDC motor is designed and the electrical characteristics are analyzed using FEA program and the power electronics drives for the 7-phase BLDC motor are theoretically analyzed and the actual implementation has been accomplished using Matlab Simulink. PI controller and fuzzy controller are compared for verifying the validity of the proposed model and the informative results are described in detail. Especially A fuzzy controller is used to characterize 7-phase BLDC motor, drive systems under normal and fault operating conditions.

• Journal of Power Electronics
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• v.19 no.3
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• pp.761-770
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• 2019

This paper proposes a hybrid phase windings excitation method for improving the efficiency of a 7-phase brushless DC (BLDC) motor in the electric propulsion system of a ship. The electrical losses of a BLDC motor system depend on the operating region and the number of excited phase windings (2-phase, 4-phase or general 6-phase windings). In this paper the operating region and torque/speed characteristics according to the motor rotation speed and propeller load are analyzed for a number of excitation methods. In addition, it analyzes the electrical losses of the system under each of the excitation methods in the entire operating region of the motor. In every sampling time, the proposed control method calculates the electrical loss of the system for each of the excitation methods and operates a 7-phase BLDC motor by selecting the excitation method that results a decreased electrical loss at the operating speed. The usefulness of the proposed control algorithm is verified through experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.4
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• pp.575-582
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• 2014

In this paper, a simulation model for 7-phase BLDC motor drives for an Autonomous Underwater Vehicles (AUV) is proposed. A 7-phase BLDC motor is designed and the electrical characteristics are analyzed using FEA program and the power electronics drives for the 7-phase BLDC motor are theoretically analyzed and the actual implementation has been accomplished using Matlab Simulink. PI controller is used for verifying the validity of the proposed model and the informative results are described in detail.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.11
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• pp.1663-1668
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• 2017

A BLDC motor with higher number of phases has several advantages, compared to the conventional three-phase BLDC motors. It can reduce the commutation torque ripple and the iron loss without increasing the voltage per phase and increase the reliability and power density. Higher number of phases increase the torque-per-ampere ratio for the same machine volume and output power by widening the electrical conduction period. In this paper, the proposed seven-phase BLDC motor drive system is made into several functional modular blocks, so that it can be easily extended to other ac motor applications: back-EMF block, hysteresis current control block, pwm inverter block, phase current block, and speed/torque control block. Also in a system of BLDC motor drive, the PI controller has been widely used in the speed controller because of the simple implementation. To obtain a good speed response in a general drive system using the PI controller, the high bandwidth of a controller is established. therefore, in this paper, a Fuzzy controller is applied to the 7-phase BLDC motor drive system in order to improve the speed control performance. The Fuzzy controller is compared with a conventional PI controller through the experiment with respect to speed dynamic responses. These experimental results show that the Fuzzy controller of the 7-phase BLDC motor drive system is superior over the conventional PI controller. The algorithm using the Fuzzy controller can improve a comfortable ride in the field of high performance 7-phase BLDC motor drive applications.

• Journal of Power Electronics
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• v.7 no.2
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• pp.132-139
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• 2007

Electrical motors are an integral part of industrial plants with no less than 5 billion motors built world wide every year. The demand for low-cost brushless DC (BLDC) motors has increased in industrial applications. This paper presents a BLDC motor control algorithm for low-cost motor drive applications using general purpose microcontrollers which have only one on-chip timer. This paper describes how to realize pulse width modulation (PWM) signals with general input/output (I/O) ports to control a three-phase permanent magnet brushless DC motor using the timer interrupt on MSP430F1232.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.7
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• pp.1314-1320
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• 2001

DC motors have widely been used in the field of variable-speed driving system since it is easy to control flux and torque of the motors precisely but it is hard to check and maintain those periodically. In addition, there are difficulties in high power and high speed running due to rectifying limit of commutator, and are a lot of restrictions in installation. Therefore, speed control in BLDC(Brushless DC) motors have seriously been studied for a long while. In this paper, a mathematical model of BLDC motor driven by PWM inverter is developed. Dynamics and steady-state characteristics of BLDC motor are simulated and analyzed with a series of experiments for the parameter estimation : torque, speed, phase voltage and current.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.5
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• pp.449-456
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• 2017

This study proposes a method for compensating for the commutation torque ripple of delta-connected brushless DC motors with low inductance based on a current predictions. At the commutation instant, a phase current at the next sampling period is predicted and compared with the reference phase current to determine whether torque ripples will occur or not. If the predicted current cannot reach the reference phase current, the reference current is modified and the relevant voltage reference is produced to reduce the torque ripple. The validity of the proposed method has been verified by simulation and experimental results. The commutation torque ripple has been decreased by 17.7% at 1,000 rpm and 80% load conditions.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.7
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• pp.675-682
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• 2009

Instead of direct driving like BLDC, the induction principle is adopted as a driving one for planar stage. The stage composed of four linear induction motors put in square type is activated by two-axial forces; low-frequency attractive force and thrust force of the linear induction motors. Here, the modified vector control whose new inputs are q-axis current and dc current biased to three phase current instead of d-axis current or flux current is applied extensively to overall motion of the stage. For the developed system, the precision step test and the constant velocity test are tried to guarantee its feasibility for TFT-LCD pattern inspection. However, to exclude a discontinuity due to phase shift and minimize a force ripple synchronized with the command frequency, the initial system is revised to the antagonistic structure over the full degree of freedom. Concretely describing, the porous air bearings guide an air-gapping of the stage up and down and a pair of liner induction motors instead of single motor are activated in the opposite direction each other. The performances of the above systems are compared from trapezoid tracking test and sinusoidal test.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.1170-1175
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• 2005

This paper is analyzed the characteristic of multi-phase inverter for the electric propulsion system. Two BLDC motors with 3 and 7 phases are designed with these features in order to simulate the effect of increasing the number of phases. From the simulation results, the 7-phase given better performance in terms of torque pulsation. Also, the torque pulsation can be reduced further by increasing the number of phases.