• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1569-1576
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• 2014

This paper mainly proposes a direct torque control strategy to minimize torque ripple in brushless DC (BLDC) motor. BLDC motor has large current and torque ripple when one voltage vector applied in one cycle due to its low inductance. Hence, this paper proposed a hysteresis torque control with PWM mode to control the resultant torque. Moreover, when the direct torque control system is operating during the two-phase half-bridge $120^{\circ}$ conduction mode, large torque ripple in commutation area appears every 120 electrical degree. Based on analyzing the root of torque ripple in detail, lookup tables of switching devices states for new half-bridge modulation mode in the positive and negative reference torque put forwarded. Finally, simulations by MATLAB software and experiment results from DSP are presented to verify the feasibility and effectiveness of the proposed strategy operating in four-quadrant operation.

• Journal of Power Electronics
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• 제15권2호
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• pp.497-503
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• 2015

This paper analyses the harmonic pollution to power grids caused by several high-power rectifiers, summarizes the requirements for rectifiers in suppressing grid-side current harmonics and optimizes a new-type of current source PWM rectifier with a hybrid switch. The rectifier with a hybrid switch boasts significant current characteristics and cost advantages in the high-power area. To further enhance the working frequency of the current source rectifier with a hybrid switch for suppressing grid-side harmonics and reducing the inductance size, this paper proposes an optimal control strategy based on space vector. It also verifies that the optimal control strategy based on space vector can reduce the total harmonic distortion of the grid-side current of the rectifier with a hybrid switch via circuit simulation and experimental results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.512-513
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• 2012

The electric motor is essential to drive turbo machinery. In order to overcome the speed limitations of general motors, the inverter is used to perform high speed to tens of rpm. The high speed drives are widely used in many applications such as turbo blower, turbo centrifugal compressors, and pump using air bearing technique. Starting of high speed motor can cause step out, stall, oscillation of motor because the phase inductance is much smaller than that of ordinary motor. This paper studied on the starting characteristic of variable speed centrifugal chiller considering high speed motor characteristics. Finally, the superiority of the inverter is verified by experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1020-1022
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• 1993

The speed control associated with do send motors for direct-drive applications of mobile robot is considered. In odor to the high-performance operation of dc servo motor, drive circuits is controlled Pulse Width Modulations. In this case, PWM driving circuit has nonliner charactristics. This circuit composed of H-type bridge with freewheeling diodes in odor to deal with storage energy of motor's inductance and also control method is developed. At resultes, speed charactristics of motor is shown lineristics. In oder to speed control of motor. The opertion of phase-locked servo system is described and a linear discrete model is developed to their behavior. Thise model discussed are the design problems, speed variation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.122-124
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• 2001

In this paper, the influence of electrical parameters such as the turn-on and turn-off angle on the torque and force characteristics is investigated for the reduction of the torque ripple which is main source of vibration and noise in switched reluctance motor (SRM). The four different types of the turn-on angle are set to the section of rising inductance profile respectively. The optimum turn-on angle is proposed for the acquisition of the flat current shape minimizing the torque ripple. 2D finite element method (FEM) considering the iron saturation and the actual switching circuit of the SRM drive is applied for the dynamic analysis. The simulation results of phase current and torque are also compared to the experimental results.

• Journal of Power Electronics
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• 제17권4호
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• pp.860-873
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• 2017

The present article reports an analysis and investigation of a direct AC-AC quasi-resonant converter. A bidirectional power device, whose switching frequency is lower than the frequency of the current passing through the load, is used for its realization. The zero voltage switching mode is described when zero voltage on the power device is available by measuring it with the control system. The continuous current in the resonant inductance by switching the power device at zero voltage is considered, and it is characterized by two sub-modes. A mathematical analysis of the processes has been made and comparative results from the computer simulation and experimental study have been brought. The converter can be used in a wide areas of power electronics: induction heating, wireless power transfer, AC-DC converters, etc.

• 전자공학회논문지
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• 제52권2호
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• pp.70-74
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• 2015

본 논문에서는 직교송신부에 $90^{\circ}$ 위상 천이된 전력 입력방식을 사용하여 2차원의 공진형 무선전력전송 송, 수신기를 설계 및 구현하였다. 제안한 송신기 각각의 직교 코일을 사용하여 상호 인덕턴스를 최소화하였으며 $90^{\circ}$ 위상 천이된 전력 입력방식을 사용하여 2차원의 공간으로 자계 에너지를 방사하도록 설계하였다. 이는 일반적인 무선전력 전송에서 위치에 따라 전송효율이 급격히 감소되는 문제점을 해결하여 2차원공간의 공진형 무선전력 전송을 가능케 한다. 이때의 공진주파수는 6.78 MHz이며, 송수신 공진기의 사이 거리가 200 mm일 때, 2차원 전 방향에서 40 % 이상의 무선전력 전송효율을 얻을 수 있다.

• 전력전자학회논문지
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• 제18권1호
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• pp.10-17
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• 2013

In this paper, a new active damping method of LCL filter without capacitor voltage sensors is proposed for 3 phase PWM Inverter. Normally, L filter or LCL filter is used as an output filter of grid connected PWM inverter. An LCL filter has more excellent performance than L filter to reduce harmonic current, so the small inductance value can be used. However, the resonance problem in LCL filter is happen due to the zero impedance by the addition of LC branch. To solve the resonance problem, the various active damping method has been proposed so far. Generally, the virtual resistor active damping methods is required to additional hardware sensors for measurement of capacitor voltage and current. In this paper, the new active damping method is proposed without any capacitor voltage or current sensors. In the proposed method, the resonance component of the capacitor voltage of LCL filter can be observed by a simple MRAS(Model Reference Adaptive System) observer without additional hardware sensors, and this component is suppressed by feedforward compensation. The validity of the proposed method is proven by simulation and experiment on the 3-phase PWM inverter system.

• 한국전자파학회논문지
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• 제18권2호
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• pp.177-182
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• 2007

본 논문은 InGaP/GaAs HBT 공정을 통해 제작한 적응성궤환 잡음제거시스템용 낮은 위상잡음을 갖는 LC 차동 전압제어 발진기를 제안합니다. 전압제어 발진기는 필터링 기술을 포함한 향상된 공진 탱크 구조를 갖습니다. 비대칭 인덕터 대칭 캐패시터 구조로 제안된 전압제어 발진기의 출력 가변 범위는 207 MHz입니다. 출력 전력은 balun과 케이블 손실을 포함하여 -6.68 dBm입니다. 10 kHz, 100 kHz, 1 MHz에서의 위상잡음은 각각 -102.02, -112.04 그리고 -130.4 dBc/Hz입니다. 이 전압제어 발진기는 총 $0.9{\times}0.9mm^2$ 면적 내에 집적화되었습니다.

• 전기학회논문지
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• 제66권2호
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• pp.328-338
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• 2017

In this paper, a zero torque control scheme adopting current sharing function (CSF) used in integrated Switched Reluctance Motor (SRM) drive with DC battery charger is proposed. The proposed control scheme is able to achieve the keeping position (KP), zero torque (ZT) and power factor correction (PFC) at the same time with a simple novel current sharing function algorithm. The proposed CSF makes the proper reference for each phase windings of SRM to satisfy the total charging current of the battery with zero torque output to hold still position with power factor correction, and the copper loss minimization during of battery charging is also achieved during this process. Based on these, CSFs can be used without any recalculation of the optimal current at every sampling time. In this proposed integrated battery charger system, the cost effective, volume and weight reduction and power enlargement is realized by function multiplexing of the motor winding and asymmetric SR converter. By using the phase winding as large inductors for charging process, and taking the asymmetric SR converter as an interleaved converter with boost mode operation, the EV can be charged effectively and successfully with minimum integral system. In this integral system, there is a position sliding mode controller used to overcome any uncertainty such as mutual inductance or DC offset current sensor. Power factor correction and voltage adaption are obtained with three-phase buck type converter (or current source rectifier) that is cascaded with conventional SRM, one for wide input and output voltage range. The practicability is validated by the simulation and experimental results by using a laboratory 3-hp SRM setup based on TI TMS320F28335 platform.