Virtual DC Machine 제어를 이용한 UPS 시스템의 DC 링크 전압 강건성 향상 = Improved DC Link Voltage Robustness in UPS Systems Using Virtual DC Machine Control

다국어 초록 (Multilingual Abstract)

Large critical loads such as data centers require uninterrupted, high quality power,
making online UPS systems with rectifier-inverter double conversion widely used due
to their seamless transfer capability. Nevertheless, abrupt load changes can cause
significant DC link voltage deviations in both normal mode and energy stored mode.
An analysis of the energy flow and control structure in each mode clarifies how load
transients induce DC link voltage fluctuations. To reduce these deviations, a Virtual
DC Machine based DC link voltage control structure is adopted to emulate virtual
inertia and damping in a purely control based manner. An equivalent electrical model
with virtual inertia, virtual damping, and virtual armature resistance is derived from
DC machine dynamics and incorporated into the DC link voltage regulation loop. By
deriving and comparing transfer functions with a conventional voltage controller, the
VDCM approach achieves improved voltage disturbance rejection and stability under
the same bandwidth condition. Since the transient response strongly depends on
parameter selection, sensitivity is systematically evaluated using Bode plots, pole zero
maps, and step responses, and practical tuning guidelines are provided. Simulations
and experimental results verify that DC link voltage fluctuations under load steps are
effectively suppressed and that transient characteristics can be shaped as intended by
adjusting the VDCM parameters.

목차 (Table of Contents)

• 1. 서 론 １
• 1.1 연구의 배경 및 목적 １
• 1.2 논문의 구성 5
• 2. UPS 회로 구성 및 운전 6
• 2.1 Static UPS의 운전방식에 따른 분류 8
• 2.2 Online UPS 부하 연결/탈락 시 전압 변동 13
• 2.3 VDCM을 통한 전압 변동 저감 제어 16
• 3. 부하 연결/탈락 시 UPS 전압 변동 저감 제어 23
• 3.1 UPS 배터리 모드에서의 VDCM 적용 24
• 3.2 UPS 정상 모드에서의 VDCM 적용 47
• 3.3 인버터측 DC 전류 전향보상 63
• 4. 시뮬레이션 결과 66
• 4.1 제어 기법 시뮬레이션 검증 결과 66
• 5. 실험 결과 74
• 5.1 실험 세트 구성 74
• 5.2 Conventional 및 VDCM 제어 적용 실험결과 76
• 5.3 VDCM 파라미터에 따른 실험결과 78
• 6. 결론 82
• 참 고 문 헌 84
• (ABSTRACT) 87