• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.3
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• pp.11-19
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• 1997

본 논문에서는 스위치드 리럭턴스 전동기의 토크 리플 또는 소음을 감소하기 위한 방법으로써 순시 전압제어방식을 제시하였다. 이 방식은 상 정류의 제곱의 합ㅇ르 제어하여 토크 리플을 제거할 수 있다. 제안방식에 대해 해석하였으며, 이 방식의 이론적인 타당성을 입증시키기 위해 소프트웨어 페키지 ASCL에 의해 시뮬레이션하였다. 실험에 의해 SRM 토크 리플의 제거를 확인하였다.

• Journal of Power Electronics
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• v.16 no.2
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• pp.436-446
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• 2016

A novel step-up DC-DC converter with a switched-coupled-inductor-capacitor (SCIC) which successfully integrates three-winding coupled inductors and switched-capacitor techniques is proposed in this paper. The primary side of the coupled inductors for the SCIC is charged by the input source, and the capacitors are charged in parallel and discharged in series by the secondary windings of the coupled inductor to achieve a high step-up voltage gain with an appropriate duty ratio. In addition, the passive lossless clamped circuits recycle the leakage energy and reduce the voltage stress on the main switch effectively, and the reverse-recovery problem of the diodes is alleviated by the leakage inductor. Thus, the efficiency can be improved. The operating principle and steady-state analyses of the converter are discussed in detail. Finally, a prototype circuit at a 50 kHz switching frequency with a 20-V input voltage, a 200-V output voltage, and a 200-W output power is built in the laboratory to verify the performance of the proposed converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.4
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• pp.388-396
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• 2005

SRM has not been put into practical applications widely because of its large torque ripple, acoustic noise and low power factor. In addition, a traditional position sensor is needed for the drive control. So we propose an improved sensorless drive method of Switched Reluctance Motors using impressed voltage pulses. Conventional impressed voltage pulse method has a problem of phase delay because of low-pass filter. So in this paper we propose an unproved sensorless driving method based on the impressed voltage pulse using new pulse-shift circuit technique that overcomes the phase delay and start-up problem. Proposed method is implemented in a simple analog circuit instead of using an expensive DSP.

• Journal of Power Electronics
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• v.17 no.5
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• pp.1173-1185
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• 2017

In this paper, a new single phase multilevel inverter topology with a single DC source is presented. The proposed topology is developed based on the concepts of the L-Z source inverter and the switched capacitor multilevel inverter. The input voltage to the proposed inverter is boosted by two steps: the first step by an impedance network and the second step by switched capacitor units. Compared to other existing topologies, the presented topology can produce a higher boosted multilevel output voltage while using a smaller number of components. In addition, it provides more flexibility to control boosting factor, size, cost and complexity of the inverter. The proposed inverter possesses all the advantages of the L-Z source inverter and the switched capacitor multilevel inverter like controlling the start-up inrush current and capacitor voltage balancing using a simple switching strategy. The operating principle and general expression for the different parameters of the proposed topology are presented in detail. A phase disposition pulse width modulation strategy has been developed to switch the inverter. The effectiveness of the topology is verified by extensive simulation and experimental studies on a 7-level inverter structure.

• Journal of Power Electronics
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• v.11 no.6
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• pp.897-903
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• 2011

Many voltage sag compensators have been introduced, including the traditional dynamic voltage restorer (DVR), which requires an energy storage device but is inadequate for compensating deep and long-duration voltage sags. The AC-AC sag compensators introduced next do not require a storage device and they are capable of compensating voltage sags. This type of compensator needs an AC-AC converter to regulate the output voltage. Presented in this paper is a three-phase PWM-switched autotransformer voltage sag compensator based on an AC-AC converter that uses a proposed detection technique and PWM voltage control as a controller. Its effectiveness and capability in instantly detecting and compensating voltage sags were verified via MATLAB/Simulink simulations and further investigated through a laboratory prototype developed with a TMS320F2812 DSP as the main controller.

• Journal of Power Electronics
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• v.16 no.1
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• pp.277-286
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• 2016

This paper offers two Maximum Power Point Tracking (MPPT) systems for Photovoltaic (PV) applications. The first MPPT method is based on a fixed frequency Model Predictive Control (MPC). The second MPPT technique is based on the Predictive Hysteresis Control (PHC). An experimental demonstration shows that the proposed techniques are fast, accurate and robust in tracking the maximum power under different environmental conditions. A DC/DC converter with a high voltage gain is obligatory to track PV applications at the maximum power and to boost a low voltage to a higher voltage level. For this purpose, a high gain Switched Inductor Quadratic Boost Converter (SIQBC) for PV applications is presented in this paper. The proposed converter has a higher gain than the other transformerless topologies in the literature. It is shown that at a high gain the proposed SIQBC has moderate efficiency.

• Journal of Power Electronics
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• v.13 no.5
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• pp.766-778
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• 2013

The depletion of natural resources and renewable energy sources, such as photovoltaic (PV) energy, has been highlighted for global energy solution. The PV power control unit in the PV power-generation technology requires a high step-up DC-DC converter. The conventional step-up DC-DC converter has low efficiency and limited step-up ratio. To overcome these problems, a novel high step-up DC-DC converter using an isolated switched capacitor cell is proposed. The step-up converter uses the proposed transformer and employs the switched-capacitor cell to enable integration with the boost inductor. The output of the boost converter and isolated switched-capacitor cell are connected in series to obtain high step-up with low turn-on ratio. A hardware prototype with 30 V to 40 V input voltage and 340 V output voltage is implemented to verify the performance of the proposed converter. As an extended version, another novel high step-up isolated switched-capacitor single-ended DC-DC converter integrated with a tapped-inductor (TI) boost converter is proposed. The TI boost converter and isolated-switched-capacitor outputs are connected in series to achieve high step-up. All magnetic components are integrated in a single magnetic core to lower costs. A prototype hardware with 20 V to 40 V input voltage, 340 V output voltage, and 100 W output power is implemented to verify the performance of the proposed converter.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1706-1715
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• 2016

In this paper, a single phase modified switched-diode topology for both symmetrical and asymmetrical cascaded multilevel inverters is presented. It consists of a Modified Switched-Diode Unit (MSDU) and a Twin Source Two Switch Unit (TSTSU) to produce distinct positive voltage levels according to the operating modes. An additional H-bridge synthesizes a voltage waveform, where the voltage levels of either polarity have less Total Harmonic Distortion (THD). Higher-level inverters can be built by cascading MSDUs. A comparative analysis is done with other topologies. The proposed topology results in reductions in the number of power switches, losses, installation area, voltage stress and converter cost. The Nearest Level Control (NLC) technique is employed to generate the gating signals for the power switches. To verify the performance of the proposed structure, simulation results are carried out by a PSIM under both steady state and dynamic conditions. Experimental results are presented to validate the simulation results.

• Journal of Energy Engineering
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• v.12 no.1
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• pp.42-48
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• 2003

In system planing and operation, voltage and reactive power control is very important. The voltage deviation and system losses can be reduced through control of reactive power sources. In general, there are several different reactive power sources, we used switched shunt capacitor to improve the voltage profile and to reduce system losses. Since there are many switched shunt capacitors in power system, so it if necessary to coordinate these switched shunt capacitors. In this study, Genetic Algorithm (GA) is used to find optimal coordination of switched shunt capacitors in a local area of power system. In case study, the effectiveness of the proposed method is demonstrated in KEPCO's power system. The simulation is performed by PSS/E and the results of simulation are compared with sensitivity method.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.4
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• pp.348-352
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• 2016

This paper addresses the efficient improvement of the Switched Reluctance Motor(SRM) by the proper voltage excitation. In the case of loads with large operational motor-speed differences such as washing machine, an SRM system driven by a constant DC-link voltage is not useful for improving the efficiency. To reduce the effect of the excess DC-link voltage, AC-DC control converter that uses a silicon controlled rectifier instead of diode rectifier is employed in the SRM driver system. AC-DC control converter supplies a proper link voltage for low-speed operation. The experimental results demonstrated that the efficiency of the system was improved at low speeds.