• 전기학회논문지
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• 제65권4호
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• pp.576-585
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• 2016

The current control methods of Y-connected 7 Phase BLDC motor are sine wave current control and square wave control. The sine wave current control method needs dq axis transformation of $7{\times}7$ matrix for current control and very complex. Also this method is not suitable for multi Phase BLDC motor of trapezoidal back emf wave. Therefore, in Y connected multi phase BLDC motor, the square wave current control methods are required. Generally, in the 3Phase BLDC system, Average current control method is used for current control. The average current is obtained that the summation of absolute value of each phase current magnitude is divided by the number of conduction phase. However, if average current control method is applied to multi-phase system, there is a problem that each phase currents are different. This problem affects unbalance of each phase torque and fluctuation of total torque. This paper proposed each phase current control method of Y connected 7Phase BLDC system. Proposed method is used for PI controller of each phase for each phase current control. This method can perfect square wave current control. Also, configuration of the method is easier than DQ axis transformation. Proposed method is verified through simulation and experiments.

• 한국조명전기설비학회지:조명전기설비
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• 제5권2호
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• pp.84-95
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• 1991

Mostly, phase control method is used to control the single phase AC power. The phase control method has some advantages such as ease to control and simple configuration. But the retardation of firing angle causes a lagging current even if load is purely resistive. So phase control causes a lagging power factor and a low efficiency at the input side in comparing with the system without switching device. A new PWM control method which can improve these defects for single phase AC power control circuit is proposed in this paper. The performances of the single phase AC power control circuit using the proposed method was investigated theoretically. Both power factor and waveform of load current can be improved better than those of the conventional methods.

• Journal of Electrical Engineering and Technology
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• 제4권2호
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• pp.266-271
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• 2009

In this paper, improved direct torque control(DTC) of five-phase induction motor(IM) is proposed. Due to the additional degrees of freedom, five-phase IM drives present unique characteristics. One of them is the ability of enhancing the torque producing capability of the motor. Also five-phase motor drives possess many others advantage compared with the traditional three-phase motor drives. Such as, reducing the amplitude and increasing of frequency of torque pulsation, reducing amplitude of current per phase without increasing the voltage per phase and increasing the reliability. The direct torque control method is advantageous when it is applied to the five-phase IM. Because the five-phase inverter provides 32 space vectors in comparison to 8 space voltage vectors by the three-phase inverter. The 32 space voltage vectors are divided into three groups according to their magnitudes. The characteristics and dynamic performance of traditional five-phase DTC are analyzed and new DTC for five-phase IM is proposed. Therefore, a more precise flux and torque control algorithm for the five-phase IM drives can be suggested and explained. For presenting the superior performance of the pro-posed direct torque control, experimental results is presented using a 32 bit fixed point TMS320F2812 digital signal processor

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.366-373
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• 1998

In this paper, a new control strategy to reduce switching losses in three-phase voltage-source PWM converters is proposed according to Modified-Period-Average-Model (MPAN). The basic concept of this strategy is aimed at calculating the phase control voltages for controlling the source currents to be sinusoidal and in phase with the source voltages, and reducing the number of switching in each period. The phase control voltages of Period-Average-Model(PAM) is obtained according to analyzing the operation of PWM converter. In order to reduce the sensitivity to system parameters in PAM, MPAM is deduced. Then a square wave whose frequency is three times of utility frequency is added to the phase control voltages derived from MPAM. The control strategy reduces the switching losses since there exists about one-third blanking time for every phase in one period. The theoretical derivation and the control strategy are experimentally verified on a 2.5 kW three-phase voltage source converter.

• 대한전기학회논문지
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• 제38권7호
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• pp.481-491
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• 1989

A compensation strategy for the phase-difference control method, which has been reported as a new driving method of a 2-phase inverter-fed induction motor, is proposed. The phase-difference control method extends the control range of the speed and eliminates the harmonic contents of the output voltage of the 2-phase inverter-fed induction motor. However, the phase-difference angle becomes narrower, motor efficiency deceases more and pulsating torque increases more. As the counterplan for these shortcomings of the phase-difference control method, a hybrid control method which combines the phase-difference control with the voltage control is proposed. The algorithm to realize a hybrid method is presented. As an example, a model composed of 5 regions has been analyzed by computer simulation in terms of motor performance and the results have been compared with experimental results.

• 반도체디스플레이기술학회지
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• 제17권3호
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• pp.90-94
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• 2018

In this paper, we applied a three-level T-type inverter with the one more voltage level than two-level inverter. However, the three-level T-type inverter has a systematic problem with voltage unbalances. So neutral point control is essential. Therefore, the voltage unbalance problem of the three - phase inverter was confirmed to be controlled within 5V using the neutral point control algorithm in charge and discharge mode. In addition, total harmonic distortion was reduced in three phases (u phase, v phase, w phase) when neutral point control was performed in charging mode and also in three phases (u phase, v phase, w phase) in discharge mode. In this paper suggests a neutral point control algorithm to solve the voltage unbalance of a three-level T-type inverter, and shows the improvement of the performance of the proposed algorithm through experiment.

• 전력전자학회논문지
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• 제12권4호
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• pp.310-317
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• 2007

본 논문에서는 평형 2상유도전동기에 대한 시스템 방정식을 유도하고 해석하였으며, 동기좌표계에서 평형 2상유도전동기의 속도제어 특성을 분석하였다. 3상 교류 전동기의 속도제어에 범용적으로 적용하는 벡터제어이론을 "2상 인버터 구동 2상 유도전동기 시스템"에 수정하여 적용하였으며, 이 때 2상 유도전동기 시스템은 수정된 간접 벡터제어이론에 의해 속도 제어하였다. 2상 유도기의 벡터제어의 특성과 근사함을 보여주기 위해 제안 시스템을 시뮬레이션하였다. 최종적으로 실험을 통해서 제안 시스템이 벡터제어에 확실히 적응하는 것을 확인하였다.

• 전력전자학회논문지
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• 제26권4호
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• pp.256-262
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• 2021

Six-phase motors can be used in industrial applications, such as an electric vehicle, due to their high reliability and low current magnitude per phase. An asymmetrical PMSM with two sets of three-phase windings is a commonly used structure for six-phase motors, with each winding set demonstrating a phase difference of 30°. Although the asymmetrical PMSM presents low torque ripples, its dynamic torque response deteriorates due to coupled components in the two three-phase windings. The decoupled VSD control is applied to eliminate the coupling effect. Load ratio control of two inverters for the six-phase PMSM is proposed in this study. DQ currents are controlled on the basis of two synchronous reference frames, and the six-phase drive system can be changed to a three-phase drive system when one inverter presents fault conditions. The operation and effectiveness of the proposed algorithm is verified through simulation and experiments. The six-phase drive system is transferred to a three-phase drive system by changing the current reference of the second DQ reference frame. Moreover, control of both torque and speed exhibits satisfactory performance before and after the mode change.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.949-952
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• 1996

The ultrasonic motor(USM) has good characteristics such as compact size, silent motion, low speed, high torque and high speed response. The USM is driven by 2-phase AC electricity. The control parameters of USM are voltage, phase difference, frequency of input power, etc. In this paper, we propose voltage difference control. And we designed USM controller to adjust voltage and phase using pLSI(programmable Large Scale Integration). Voltage difference control has many advantages that are lower current, lower power than phase difference control. Especially there is nearly zero ampere at the zero point of speed and torque. we can apply this voltage difference control to the compliance control of DD manipulator.

• Journal of Electrical Engineering and Technology
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• 제3권1호
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• pp.94-100
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• 2008

This paper presents a new control method of single-phase active power filter (APF) for the compensation of harmonic current components in nonlinear loads. To facilitate the possibility of complex calculation for harmonic current detection of the single phase, a single-phase system that has two phases was constructed by including an imaginary second-phase giving time delay to the load current. The imaginary phase, which lagged the load current T/4 (Here T is the fundamental cycle) is used in the conventional method. But in this proposed method, the new signal as the second phase is delayed by the filter. Because this control method is applied to a single-phase system, an instantaneous calculation was developed by using the rotating reference frames synchronized to source-frequency rather than by applying instantaneous reactive power theory that uses the conventional fixed reference frames. The control scheme of single-phase APF for the current source with R-L loads is applied to a laboratory prototype to verify the proposed control method.