• Journal of Power Electronics
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• 제18권1호
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• pp.70-80
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• 2018

A novel strategy based on a zero common mode voltage pulse-width modulation (ZCMV-PWM) technique and zero-sequence circulating current (ZSCC) feedback control is proposed in this study to eliminate ZSCCs between three-level neutral point clamped (NPC) voltage source inverters, with common AC and DC buses, that are operating in parallel. First, an equivalent model of ZSCC in a three-phase three-level NPC inverter paralleled system is developed. Second, on the basis of the analysis of the excitation source of ZSCCs, i.e., the difference in common mode voltages (CMVs) between paralleled inverters, the ZCMV-PWM method is presented to reduce CMVs, and a simple electric circuit is adopted to control ZSCCs and neutral point potential. Finally, simulation and experiment are conducted to illustrate effectiveness of the proposed strategy. Results show that ZSCCs between paralleled inverters can be eliminated effectively under steady and dynamic states. Moreover, the proposed strategy exhibits the advantage of not requiring carrier synchronization. It can be utilized in inverters with different types of filter.

• 제어로봇시스템학회논문지
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• 제15권1호
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• pp.82-88
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• 2009

The output of the encoder is a digital pulse, which is also easy to be connected to a digital controller. There are various angular velocity detecting methods of M, T, and M/T. Each of them has its own properties. There is a common limitation that the angular velocity detection period is strongly dependent on the destination velocity magnitude in case of ultimate low range. They have ultimately long detection period or cannot even detect angular velocity at near zero velocity. This paper proposes a zero velocity detectable sensor algorithm with the dual encoder system. The sensor algorithm is able to keep detection period moderately at near zero velocity and even detect zero velocity within nominal period. It is useful for detecting velocity in case of changing rotational direction at which there occurs zero velocity. In this paper, various experimental results are shown for the algorithm validity.

• Journal of Power Electronics
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• 제17권1호
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• pp.88-95
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• 2017

To reduce common-mode voltage (CMV), various reduced CMV pulse width modulation (RCMV-PWM) algorithms have been proposed, including active zero state PWM (AZSPWM) algorithms, remote state PWM (RSPWM) algorithms, and near state PWM (NSPWM) algorithms. Among these algorithms, AZSPWM algorithms can reduce CMV, but they increase the number of switchings compared to the conventional space vector PWM (CSVPWM). This paper presents a new AZSPWM algorithm for reductions in both the CMV and total number of switchings in BLAC motor drives. Since the proposed AZSPWM algorithm uses only active voltage vectors for motor control, it reduces CMV by 1/3 compared to CSVPWM. The proposed AZSPWM algorithm also reduces the total number of switchings compared to existing AZSPWM algorithms by eliminating the switchings required from one sector to the next. The performance of the proposed algorithm is verified by analyses, simulations, and experimental results.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.256-262
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• 2018

This study introduces a novel Soft Switching (SS) Pulse Width Modulated (PWM) AC-DC boost converter. In the proposed converter, the main switch is turned on with Zero Voltage Transition (ZVT) and turned off with Zero Current Transition (ZCT). The main diode is turned on with Zero Voltage Switching (ZVS) and turned off with Zero Current Switching (ZCS). The auxiliary switch is turned on and off with ZCS. All auxiliary semiconductor devices are turned on and off with SS. There is no extra current or voltage stress on the main semiconductor devices. The majority of switching energies are transferred to the output by auxiliary transformer. Thus, the current stress of auxiliary switch is significantly reduced. Besides, the proposed converter has simple structure and ease of control due to common ground. The theoretical analysis of the proposed converter is verified by a prototype with 100 kHz switching frequency and 500 W output power. Furthermore, the efficiency of the proposed converter is 98.9% at nominal output power.

• Safety and Health at Work
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• 제13권3호
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• pp.372-375
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• 2022

In the globalized field of safety, health, and well-being, the need to build multi-stakeholder alliances to find solutions to complex challenges is growing. This requires common ground for collaboration, as well as concepts and tools to grasp and manage the areas of interest. Over recent years, Vision Zero has awakened interest and it continues to evolve into many forms of approaches and initiatives, which provide a strategic direction and practical tools for supporting the development of safety, health, and well-being at work. Consequently, there is a need to build a shared understanding of 'zero'. This article reflects the potential of Vision Zero as a bridging concept and an approach for building multi-stakeholder collaboration. Thus, we present a multi-perspective framework of Vision Zero to support further dialoge and collaboration in joint undertakings.

• 한국지열·수열에너지학회논문집
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• 제8권2호
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• pp.27-35
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• 2012

Five zero energy house models developed in Korea for the purpose of the energy performance were compared and analyzed in the study. The standard passive house model applying common technology and efficient energy performance elements was proposed. Standard passive house 5 models have been developed commonly aiming at 100% energy saving, applying high-performance and high-efficiency exterior thermal insulation, using 3 low-e coated window system, and targeting average 0.65 ACH to enhance privacy. Energy recovery ventilators and dry and cold radiant heating floor has been partially applied. Eco-design techniques such as the awning device, heat insulating door, using natural light have been used. Solar and geothermal systems as the application of renewable energy technologies have been commonly applied. And fuel cells were applied to a partial model. The standard model based on common technical elements and average performance of each element and obtained from five model analysis has been proposed in the study.

• 전력전자학회논문지
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• 제26권2호
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• pp.135-140
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• 2021

This study introduces a new pulse width modulation (PWM) method to reduce common-mode voltages (CMVs) and then compares its performance with other reduced CMV-PWM (RCMV-PWM) methods. CMVs should be reduced to ensure the electromagnetic compatibility and safety of grid-connected inverters. RCMV-PWM methods attempt to synthesize voltage references without zero vectors, which cause high CMV peaks. In these methods, the peak-to-peak magnitude of CMVs can be reduced by one-third of the conventional space-vector PWM. The introduced method splits every reference vector into two vectors to avoid the use of zero vectors. The performances of the RCMV-PWM methods are analyzed in accordance with the modulation index through simulation and experiment.

• 전력전자학회논문지
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• 제8권1호
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• pp.89-97
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• 2003

PWM 인버터에 의해 구동리근 유도전동기에 발생되는 고주파 커먼 모드 전압은 전도성 EMI, 전통기 접지전류, 베어링 전류 및 다른 원치 않는 결과의 주원인이 된다. 인버터 제어의 무효벡터 스위칭 상태는 나머지 유효벡터 스위칭 상태에 비교하여 큰 커먼 모드 전압을 일으킨다. 그러므로 이 논문은 커먼 모드 전압을 완화하는 스위칭기법을 다룬다. 즉 정현파 PWM 기법을 기본으로 한 커먼 모드 전압 제거방법을 제안하였다. PWM 신호는 각자의 정현과 기준신호와 120$^{\circ}$위상차가 나는 3개의 캐리어 파형과 비교하여 발생된다. 시뮬레이션과 실험적 결과는 제안된 PWM 기법에서 커먼 모드 전압이 종래의 PWM 기법보다 약 66% 더 저감됨을 보였다.

• 한국정밀공학회지
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• 제24권9호
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• pp.76-85
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• 2007

An optical rotary encoder is easy to implement for automatic control applications. In particular, the output of the encoder has a digital form pulse, which is also easy to be connected to a popular digital controller. By using the encoder, there are various angular velocity detecting methods, M-, T-, and M/T-method. Each of them has a property of its own. They have common limitation that the angular velocity detection period is strongly subject to the destination velocity magnitude in case of ultimate low range. They have ultimate long detection period or cannot even detect angular velocity at near zero velocity. This paper proposes a dual encoder system with two encoders of normal resolution. The dual encoder system is able to keep detection period moderately at near zero velocity and even detects zero velocity within nominal period. It is useful for detecting velocity in case of changing rotational direction at which there occurs zero velocity. In this paper, various experimental results are shown for the dual encoder system validity.

• 한국정밀공학회지
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• 제32권1호
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• pp.17-24
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• 2015

Smart factory requires 4 Zero factors including Zero Waiting-time, Zero Inventory, Zero Defect, Zero Down-time) that needs IT convergence for production resources of 4M1E(Man, Machine, Material, Method, Energy) in real time and event processing in all type of manufacturing enterprises. This paper will be explaining about core emerging production IT convergence technologies including cyber device security, 4M1E integration, real time event driven architecture, common platform of manufacturing standard applications, smart factory to-be model for small and medium manufacturing enterprises.