• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.385-387
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• 1999

Brushless DC Motors are widely used because of their high power ratio and easy control. But the brushless DC Motors need rotor Position- and speed- sensor such as encoder, resolver and hall sensor. The position sensor has present several disadvantages from the standpoint of drive cost, machine size and reliability. Hall sensors are used generally because of low cost but their operating temperature is limited up to $75^{\circ}C$ because of sensitivity of temperature. Now a day many research projects are on the development of sensorless brushless DC motors to correct these disadvantages. In this paper, characteristics such as starting, change of speed and load of a sensorless brushless DC motor are investigated.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.9
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• pp.600-608
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• 1988

Although the structure of brushless dc motor is similar to that of a Permanent magnet synchronous motor, its torque-speed characteristcis are the same as those of a permanent magmet dc motor. The brushless dc motor drive systemcomposed of power converter including inverter, rotor positioning sensor and controller has been investigated for the purpose of position control when the motor is fed by a current controlled voltage source inverter. The equivalent transformation of a brushless dc motor into an separately exited dc motor has been possible with the vector control (field oriented control) technique. It is shown in this paper that the position control of a brushless dc mitor can be done fairly accurately only using q-axis current.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.866-872
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• 2014

The purpose of this paper was to find an effective method for measuring electromagnetic torque produced by a brushless DC motor with single-phase current sensing in real-time. A torque equation is derived from the theory of brushless DC motor. This equation is then validated experimentally with a motor dynamometer. A computer algorithm is also proposed to implement the electromagnetic torque estimation equation in real-time. Electromagnetic torque is a linear function of phase current. Estimating the electromagnetic torque in real-time using single-phase current is not appropriate with existing equations, however, because of the rectangular alternating-pulse nature of the excitation current. With some mathematical manipulation to the existing equations, the equation derived in this paper overcame this limitation. The equation developed is simple and so it is computationally efficient, and it takes only motor torque constant and single-phase current to evaluate the electromagnetic torque; no other parameters such as winding resistances, inductances are needed. The equation derived is limited to the three-phase brushless DC motor. It can, however, easily be extended to the multiphase brushless DC motor with the technique described in this paper.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.5
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• pp.310-316
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• 2013

This paper reports a sinusoidal $180^{\circ}$ drive for a permanent magnet (PM) brushless motor employing automatic angle compensator to suppress the driving loss during the wide-range load operation. The proposed drive of the sinusoidal $180^{\circ}$ PM Brushless motor reduced the amplitude of the 3-phase current by compensating for the lead-angle of the fundamental waves of the 3-phase PWM signal. The conventional lead-angle method was implemented using the fixed angle or memorized table, whereas the proposed method was automatically compensated by calculating the angle of the current and voltage signal. The algorithm of the proposed method was verified in a 30 W PM brushless motor system using a PSIM simulator. The efficiency of the conventional method was decreased 90 % to 60 %, whereas that of proposed method maintained approximately 85 % when the load shift was 0 to $0.02N{\cdot}m$. Using an FPGA prototype, the proposed method was evaluated experimentally in a 30 W PM brushless motor system. The proposed method maintained the minimum phase RMS current and 79 % of the motor efficiency under 0 to $0.09N{\cdot}m$ load conditions. The proposed PM brushless motor driving method is suitable for a variety of applications with a wide range of load conditions.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.3
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• pp.195-202
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• 2004

This paper presents a current control strategy to reduce torque ripple of Brushless DC Motor during con)mutation. The torque ripple is mainly caused by the inequality in the rate of change between rising current and decaying one during commutation. And also it is influenced by the shape of real back EMF Therefore, in the proposed control strategy, considering real back EMF a compensation voltage is generated to equalize the rate of change in these commutating currents. And then, by providing the compensation voltage during commutation, the torque ripple can be reduced. The simulation md experimental results verify that the proposed method can reduce the torque and the current ripples significantly.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.1
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• pp.53-60
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• 2012

As enforced by the regulation on the improving fuel efficiency and increased the demand on green technology, many interests are focused on electric vehicles and hybrid vehicles. Thus the technology development in electrification of vehicle operation system, including steering and braking field, is actively progressive. Especially electric power steering substitutes for hydraulic power steering rapidly in the market, which is more complex and bigger in packaging volume compared with electric power steering system. The core component in electric power steering system is a motor, which is required to be silent and powerful to guarantee required system performance. Brushless synchronous motors are widely used and many variations of the motors are introduced in the market, while the performance of each type is not well defined or studied for electric power steering system. In this paper, recent developments in brushless synchronous motor are reviewed and compared applying finite element analysis in electromagnetic field. As results, each characteristic of different types of brushless synchronous motors is compared and summarized for optimized selection in electric power steering system.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.6
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• pp.34-41
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• 1993

This paper describes an effort to develop a microcomputer-based parameter identification system for three phase and two phase brushless DC motor. Back EMF equation is derived from back EMF waveform of three phase and two phase brushless DC motor. In this paper, a new identification algorithm for the brushless DC motor parameters by Pasek's technique is de veloped. It is found that Pasek's equation is valid for the brushless DC motor, too. The results obtained clearly shows that it is possible to implement the identification system for the determination of the brushless DC motor parameters. To minimize errors due to the ripple component in the measured armature current, dlgital averaging filter is employed. The whole identification process of signal generation, measuring, parameter determination is fully automated. The use of the pmpased method in the parameter identification system shows that the averaged current curve is in excellent agreement with the estimated current curve. Therefore, this close agreement conf i i the validity of this technique.

• ETRI Journal
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• v.37 no.6
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• pp.1165-1175
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• 2015

This paper presents an advanced sensorless permanent magnet (PM) brushless motor controller integrated circuit (IC) employing an automatic lead-angle compensator. The proposed IC is composed of not only a sensorless sine-wave motor controller but also an isolated gate-driver and current self-sensing circuit. The fabricated IC operates in sensorless mode using a position estimator based on a sliding mode observer and an open-loop start-up. For high efficiency PM brushless motor driving, an automatic lead-angle control algorithm is employed, which improves the efficiency of a PM brushless motor system by tracking the minimum copper loss under various load and speed conditions. The fabricated IC is evaluated experimentally using a commercial 200 W PM brushless motor and power switches. The proposed IC is successfully operated without any additional sensors, and the proposed algorithm maintains the minimum current and maximum system efficiency under $0N{\cdot}m$ to $0.8N{\cdot}m$ load conditions. The proposed IC is a feasible sensorless speed controller for various applications with a wide range of load and speed conditions.

• Journal of Power Electronics
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• v.5 no.1
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• pp.62-66
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• 2005

A simple fault correction method for rotor position detection of a brushless DC(BLDC) motor with trapezoidal back EMF(electromotive force) using a Hall effect latch unit is presented. The reason why the Hall effect latch unit does not operate properly during the startup of a BLDC motor is thoroughly explained. To solve this problem, a simple code change method and its hardware implementation issues are proposed and discussed.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.620-622
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• 1992

Magnetic characteristics of a brushless disk type motor has been analyzed taking into account the magnetization distribution in the rotor magnet. This paper describes a method for calculating the 3D flux density in the air gap and calculates the induced voltage of the windings and the torque betweens the permanent magnet and the amateur current.