• Journal of Power Electronics
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• 제19권2호
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• pp.394-402
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• 2019

This paper proposes a single-phase non-isolated onboard battery charger (OBC) for electric vehicles (EVs) that only uses small film capacitors at the DC-link of the AC-DC converter. In the proposed charger, an isolated DC-DC converter for low-voltage batteries is used as an active power decoupling (APD) circuit to absorb the ripple power when a high-voltage (HV) battery is charged. As a result, the DC-link capacitance in the AC-DC converter of the HV charging circuit can be significantly reduced without requiring any additional devices. In addition, some of the components of the proposed circuit are shared in common for the different operating modes among the AC-DC converter, LV charging circuit and active power filter. Therefore, the cost and volume of the onboard battery charger can be reduced. The effectiveness of the proposed topology has been verified by the simulation and experimental results.

• Journal of Power Electronics
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• 제15권1호
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• pp.31-38
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• 2015

In this paper, a buck-boost type battery charger is developed for charging battery set with a lower voltage. This battery charger is configured by a rectifier circuit, an integrated boost/buck power converter and a switched capacitors circuit. A boost power converter and a buck power converter sharing a common power electronic switch are integrated to form the integrated boost/buck power converter. By controlling the common power electronic switch, the battery charger performs a hybrid constant-current/constant-voltage charging method and gets a high input power factor. Accordingly, both the power circuit and the control circuit of the developed battery charger are simplified. The switched capacitors circuit is applied to be the output of the boost converter and the input of the buck converter. The switched capacitors circuit can change its voltage according to the utility voltage so as to reduce the step-up voltage gain of the boost converter when the utility voltage is small. Hence, the power efficiency of a buck-boost type battery charger can be improved. Moreover, the step-down voltage gain of the buck power converter is reduced to increase the controllable range of the duty ratio for the common power electronic switch. A prototype is developed and tested to verify the performance of the proposed battery charger.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.2089-2091
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• 2000

Pulsed power systems consist of a capacitor bank, an isolated high-voltage charging power-supply, high-current bus-work for charging and discharging and a control system. In such pulsed power systems, the operating-lifetime of the capacitors is closely dependent on the voltage reversal. Hence, most capacitor-discharging systems includes crowbar circuits. The crowbar circuit prevents the capacitor recharging with reverse voltage. Usually it consists of crowbar resistors and high pulse-current diode-stacks connected in series. The requirements for the diode-stacks are fast-recovery time and high-voltage and large-current ratings, which results in the high cost of the pulsed-power system. This paper presents a protection scheme of a charging and discharging system of a 500kJ capacitor bank using a low-cost crowbar circuit and safety-fuses.

• 전기전자학회논문지
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• 제23권1호
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• pp.306-309
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• 2019

Wireless charging is a technology of transmitting power through an air gap to an electrical load for the purpose of energy dissemination. Compared to traditional charging with code, wireless power charging has many benefits of avoiding the hassle from connecting cables, rendering the design and fabrication of much smaller devices without the attachment of batteries, providing flexibility for devices, and enhancing energy efficiency, etc. A transmitting coil and a receiving coil for inductive coupling or magnetic resonant coupling methods are available for the near field techniques, but are not for the far field one. In this paper, the wireless power transfer (WPT) circuit by using magnetic resonant coupling method with a resonant frequency of 13.45 Mhz for the low power system is implemented to measure the power transmission efficiency in terms of mutual distance and omnidirectional angles of receiver.

• 시멘트 심포지엄
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• 1호
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• pp.50-55
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• 1973

Improvement of grinding efficiency about open circuit grinding mill in cement production was investigated and the results were as follows; 1. Controlled the steel ball by charging ratio. 2. Raised the slot ratio from 3$\%$ to 4.5$\%$

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권11호
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• pp.628-634
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• 2002

A capacitor-charging power supply using high frequency inverter technology is strongly recommended for the charging section of the pulsed power supplies. A high frequency inverter swiching makes the overall system size small. The command-charging feature can guarantee the higher reliability of switching function. The protection circuit can be easily included in the system and the good regulation of charging voltage can be acieved by the feedback system. Several modules can be stacked to supply required output power and a failed module can be easily replaced. A 50-kV, 35-kW capacitor charging power supply is developed. In this paper the detailed design and test results of a prototype unit are presented.

• Journal of Power Electronics
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• 제14권1호
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• pp.183-193
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• 2014

Due to the requirements for high reliability and accuracy, safety issues for airbag ignition systems need to be studied. In this paper, a high-voltage piezoelectric converter is designed to improve these requirements in airbag ignition systems. The proposed converter includes an inverter drive circuit, a Rosen piezoelectric transformer (PZT), an output circuit and a feedback control circuit. The key components of the high-voltage piezoelectric transformer are analyzed in detail. In addition, the proposed converter system is simulated and implemented for testing. The experimental results show that when the power supply is turned on, the charging time is less than 800ms. Furthermore, the output voltage of this converter can be kept between 2.9kV and 3.1kV, under high-efficiency constant current charging mode and zero-voltage switching conditions.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권11호
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• pp.635-644
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• 2002

Many generating units can be in parallel connection to one battery and inverter. However, one of the biggest problems we encountered is that wind speed is fluctuated sharply in accordance with the unstable weather conditions. To solve this problem, we need energy storage equipment such as storage lead-acid battery. We design a system and analyze its modeling so that it supplies a stable power to the load through DC-AC inverter part. In this paper, we applied dual step-up/down buck-boost converter and dual high-frequency half-bridge converter to the proposed system. These converters are used to store energy in the battery regardless of the change of the wind speed. The operation process of two proposed types of converters for high-power battery charging is discussed along with simulation and experimental result. We design a charging circuit which is applicable in the actual wind power generation system for 30kw and confirm the circuit's validity.

• 한국의류학회지
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• 제44권6호
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• pp.1224-1239
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• 2020

This study develops a wearable solar energy harvesting device that absorbs solar energy to generate and store power which can be used during outdoor activities by users even after dark. For this study, a prototype hat for outdoor activities at night was developed after the design of a solar energy harvesting generation, storage, and delivery system was designed that could store energy to light up LEDs. First, the main control board of the system was designed to integrate the charging function, the darkness detection circuit, the battery voltage sensing circuit, and the LED driving circuit in order to reduce bulkiness and minimize the connection structure. It was designed to increase convenience. Second, the system was designed as a wearable fashion product that connected each part with fiber bands and manufacturing it so as to be detachable from the hat. Third, charging and LED operation tests show that the battery is fully charged after 5 hours even in winter when the illuminance value is low. In addition, the LED operation experiment verified the effectiveness of a buffered system that could operate the LEDs for about 3 hours at night.

• 전력전자학회논문지
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• 제3권4호
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• pp.273-279
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• 1998

본 논문에서는 제안하는 계단충전방식에서는 직렬로 연결된 전지에 있어서 각 전지의 $\Delta$V=0 시점이 서로 다름을 고려하여 각 전지별로 선택적으로 충전단계를 절환시킴으로써 과충전 또는 부족충전을 예방할 수 있도록 하였다. 또한, 각 단계의 초기에 전지간의 잔존용량의 불균등을 해소하기 위해 시분할 균등충전모드를 추가하였다. 기존의 계단충전방식에 비해 선택적 충전단계절환을 위한 간단한 회로가 추가되지만 과충전과 부족충전을 예방하므로 전지수명과 충전효율을 개선시킬 수 있다.