• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.3
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• pp.279-288
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• 2013

This paper proposes a improved speed control system for five-phase squirrel-cage induction motor(IM) injecting 3rd. current harmonic components with field oriented control (FOC) A five-phase IM drives present unique characteristics due to the additional degrees of freedom and also drives possess many others advantage compared with the traditional three-phase motor drive system, such as reducing a amplitude of torque pulsation at low frequency and increasing the reliability. In order to maximize the torque per ampere, the proposed motor has concentrated windings. The produced back-electromotive force is almost trapezoidal, and the motor is supplied with the combined sinusoidal plus third harmonic of currents. There is necessary to controlled 3rd harmonic current in order to high response characteristics. For presenting the superior performance of the proposed the speed control system, experimental results are presented using a 32-bit fixed point TMS320F2812 DSP with 1.5[kW] induction motor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.1013-1018
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• 2016

In this paper, three kinds of the inverter topologies for the variable speed drive of 2-phase induction motor are compared and analyzed. The 2-phase inverters are classified into 2-leg, 3-leg, and 4-leg types depending on the number of power switching devices. And they use the output voltage vectors of the different forms according to the inverter topologies. Based on the comparative analyzed results, the effective values of output voltage have been defined by the linear modulation range. Therefore, the motor design guideline is proposed in order to decide a rated voltage of 2-phase induction motor according to the inverter topologies. Also, the computer simulations are carried out to verify the output voltage and current characteristics of each inverter topology.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.33 no.8
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• pp.281-288
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• 1984

A new method of protecting 3-phase squirrel-cage induction motor aginst burning-out by unbalance operation is proposed. This paper studied various kinds of situations occurred by unbalance operating in 3-phase induction motor, and we provided the search coils in the slots of stator and rotor for the purpose of detecting electrical phenpmena during unbalance operation. Through experiments, we find that search coils in the slots of stator is effective method for protecting the induction motor from unbalance operating.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.4
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• pp.206-213
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• 2012

This paper propose a improved speed control system for five-phase squirrel-cage induction motor(IM) considering effects of 3rd. harmonic current components with field oriented control(FOC) A five-phase IM drives present unique characteristics due to the additional degrees of freedom and also drives possess many others advantage compared with the traditional three-phase motor drive system, such as reducing a amplitude of torque pulsation at low frequency and increasing the reliability. In order to maximize the torque per ampere, the proposed motor has concentrated windings. The produced back-electromotive force is almost trapezoidal, and the motor is supplied with the combined sinusoidal plus third harmonic of currents. There is necessary to controlled 3rd harmonic current. For presenting the superior performance of the proposed the speed control system, experimental results are presented using a 32-bit fixed point TMS320F2812 DSP with 1.5[KW] induction motor.

• Journal of Advanced Marine Engineering and Technology
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• v.6 no.1
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• pp.25-33
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• 1982

The characteristics of the stator current and torque of a small three- phase squirrel cage induction motor and studied experimentally under the situation of a single-phase operation due to various causes. Through the experiments, the torque-slip and current-slip curve of single-phase circuit as well as three-phase circuit are obtained and the needed constants are determined. The stator current and torque are calculated by the current and torque equations derived by the unbalanced circuit theory. The numerical values obtained from the above methods are compared with the experimental values under the same conditions. The results of the study are summerized as follow; 1) The values computed by the unbalanced circuit theory generally come to approach the values recorded through experiments. 2) Near the rated load, speed drop is less than 1.2 per cent of the speed of three-phase induction motor and torque reduces less than 3 per cent of it of three-phase induction motor when three-phase induction motor is run under a single-phase. On the other hand, the stator current in a single-phase circuit is more than 1.9 times of it in three-phase circuit. 3) The stalling torque in a single-phase circuit is reduced to about 41 per cent of it in three-phase circuit while the corresponding slip is moved toward the synchroneous speed and the corresponding stator current is increased.

• Journal of Electrical Engineering and Technology
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• v.3 no.2
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• pp.224-234
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• 2008

Multi-phase machines can be used in variable speed drives. Their applications include electric ship propulsion, 'more-electric aircraft' and traction applications, electric vehicles, and hybrid electric vehicles. Multi-phase machines enable independent control of a few numbers of machines that are connected in series in a particular manner with their supply being fed from a single voltage source inverter(VSI). The idea was first implemented for a five-phase series-connected two-motor drive system, but is now applicable to any number of phases more than or equal to five-phase. The number of series-connected machines is a function of the phase number of VSI. Theoretical and simulation studies have already been reported for number of multi-phase multi-motor drive configurations of series-connection type. Variable speed induction motor drives without mechanical speed sensors at the motor shaft have the attractions of low cost and high reliability. To replace the sensor, information concerning the rotor speed is extracted from measured stator currents and voltages at motor terminals. Open-loop estimators or closed-loop observers are used for this purpose. They differ with respect to accuracy, robustness, and sensitivity against model parameter variations. This paper analyses operation of an MRAS estimator based sensorless control of a vector controlled series-connected two-motor five-phase drive system with current control in the stationary reference frame. Results, obtained with fixed-voltage, fixed-frequency supply, and hysteresis current control are presented for various operating conditions on the basis of simulation results. The purpose of this paper is to report the first ever simulation results on a sensorless control of a five-phase two-motor series-connected drive system. The operating principle is given followed by a description of the sensorless technique.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.704-711
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• 2023

This paper discusses the control method of BLDC(Brushless Direct Current) motor that has similar electrical characteristics with DC motor but has improved its lifespan and reliability. The BLDC motor can improve durability and speed stability by using rotor position information to eliminate commutators that require mechanical contact with DC motors. In this study, a controller for a DC motor was designed based on the fact that the current in the windings of a BLDC motor is a square-wave current like the current flowing in the armature of a DC motor. Next, the designed controller was applied to a 3-phase BLDC motor to confirm the effectiveness of the controller. In detail, a single-phase DC motor with electrical parameter values of a three-phase BLDC motor was modeled and a PI controller for motor speed control was designed by applying the root locus method to the derived system. The speed control simulation of the DC motor was performed to confirm the validity of the controller, and the same controller was applied to the speed control of the 3-phase BLDC motor implemented in MATLAB. From the simulation, similar results of the DC motor were obtained in the 3 phase BLDC motor and confirmed the usefulness of the proposed control scheme.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.2
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• pp.191-201
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• 2001

Recently, the demand of motor for industrial, household machinery is increasing. As Switching devices and control technology are progressing, so the use of BLDC Motor is increasing. But 3-Phase BLDC Motor generally used has pulsating torque and speed variation in commutation, so the range of its application is limited to high speed operation. Especially, to solve these problems, it is necessary to increase phase of Motor, so study of Poly-Phase BLDC Motor is progressing. However, when hysteresis current controller is used, switching frequency is highly increasing. In this paper, 7-Phase BLDC Motor drive system is designed. Also MSTC(Minimum Switching Time Controller) is proposed and with simulation and experiment, there validities are verified.

• 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.

• 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.