표제지
요약
목차
I. 서론 8
1. 연구의 배경 및 목적 8
II. 전압 변조 방법에 따른 전력 반도체와 커패시터의 열 부하 10
1. 전압 변조 방법 (Pulse width mouldation method) 10
1) UP-PWM 방법 11
2) DPWM 방법 12
2. 전력 반도체의 열 부하 14
1) 전력 반도체의 전력손실 14
2) 전력 반도체의 접합온도 14
3) 전압 변조 방법에 따른 전력 반도체의 접합온도 16
3. 커패시터의 열 부하 20
1) 커패시터의 전력손실 21
2) 커패시터의 동작 온도 21
3) 전압 변조 방법에 따른 커패시터의 동작 온도 23
III. T-type 인버터의 신뢰성에 따른 최적의 클램핑 구간 선정 전략 25
1. 커패시터의 누적 손상 26
1) 커패시터의 수명 모델 26
2) 전압 변조 방법에 따른 커패시터의 누적 손상 28
2. 전력 반도체의 누적 손상 29
1) 전력 반도체의 수명 모델 29
2) 전압 변조 방법에 따른 커패시터의 누적 손상 31
3. 클램핑 구간에 따른 T-type 인버터의 시스템 수준에서의 신뢰성 32
1) 전력 반도체를 고려한 인버터의 비신뢰성 함수 34
2) 커패시터를 고려한 인버터의 비신뢰성 함수 37
3) 전력 반도체와 커패시터를 모두 고려한 인버터의 비신뢰성 함수 39
IV. 실험 결과 42
1. 실험결과 42
1) 폴 전압과 지령 전압 43
2) 출력전류와 전압 44
3) 커패시터의 중성점 전류 45
4) 효율 46
V. 결론 47
참고문헌 48
Abstract 50
Table 2.1. Simulation parameters 11
Table 2.2. Power device loss of the T-type inverter at 7kW with different clamping periods. 18
Table 2.3. DC-link capacitors loss of the T-type inverter at 7kW with different clamping periods. 23
Table 3.1. Lifetime model of parameters 26
Table 3.2. Accumulated damages of capacitors of the T-type inverter under the different clamping periods. 28
Table 3.3. Accumulated damages of power devices of the T-type inverter under the different clamping periods. 31
Table 3.4. B10 lifetime of power devices, capacitors and T-type inverter under different clamping periods[이미지참조] 38
Table 4.1. Experiment parameters 42
Fig. 1.1. Unscheduled maintenance events and costs in PV plant 8
Fig. 1.2. Reliability vulnerable devices in power electronic systems 9
Fig. 2.1. Single-phase five-level T-type inverter topology 10
Fig. 2.2. Reference voltages of two legs with UP-PWM. 11
Fig. 2.3. Reference voltages of two legs: (a) DPWM (θ=60°) and (b) DPWM (θ=180°). 12
Fig. 2.4. Thermal model of the IGBT module for T-type inverter. 14
Fig. 2.5. Power loss distributions of power devices with UP-PWM and DPWM at 7kW in a T-type inverter (a) Sx1,4 (b) Sx2,3 and (c) Dx2,3.[이미지참조] 16
Fig. 2.6. Junction temperatures of power devices of a single-phase five-level T-type inverter at 7kW (a) UP-PWM and (b) DPWM (θ=180°). 17
Fig. 2.7. Maximum junction temperatures of power devices of the T-type inverter at 7kW with different clamping periods. 18
Fig. 2.8. Effect of voltage vectors on the ripple current of DC-link capacitors: (a) large vector [PN], (b) zero vector [OO], (c) P-type small... 20
Fig. 2.9. The reference voltages and corresponding switching sequences (a) UP-PWM and (b) DPWM (θ=180°). 22
Fig. 2.10. Comparison of current of capacitor in the time and frequency domain with: (a) UP-PWM and (b) DPWM (θ=60°) 23
Fig. 2.11. Hot-spot temperature of the DC-link capacitor with respect to clamping period. 24
Fig. 3.1. Annual PV mission profile recorded in Arizona in USA (a) solar irradiation (b) ambient temperature 25
Fig. 3.2. Thermal loading of capacitor with UP-PWM and DPWM (θ=180°). 26
Fig. 3.3. Thermal loading of power devices with UP-PWM and DPWM (θ=180°) (a) Sx1,4 (b) Sx2,3 and (c) Dx2,3[이미지참조] 29
Fig. 3.4. Unreliability functions of the power devices of the T-type inverter with UP-PWM in Arizona in USA 34
Fig. 3.5. Unreliability functions of the T-type inverter considering all power devices in two legs with UP-PWM in Arizona in USA 34
Fig. 3.6. Unreliability functions of the power devices of the T-type inverter with UP-PWM in Arizona in USA 35
Fig. 3.7. Unreliability functions of the T-type inverter considering all power devices in two legs with DPWM (θ=180°) in Arizona in USA. 35
Fig. 3.8. Unreliability function considering all power devices in two legs under UP-PWM and DPWM (θ=180°). 36
Fig. 3.9. Unreliability function of the T-type inverter considering DC-link capacitors with UP-PWM 37
Fig. 3.10. Unreliability function of the T-type inverter considering DC-link capacitors with DPWM (θ=180°). 37
Fig. 3.11. Unreliability function considering two DC-link capacitors under UP-PWM and DPWM (θ=180°). 38
Fig. 3.12. Unreliability function of the inverter considering both capacitors and power devices in Arizona in the USA with UP-PWM 39
Fig. 3.13. Unreliability function of the inverter considering both capacitors and power devices in Arizona in the USA with DPWM (θ=180°). 39
Fig. 3.14. Unreliability function of T-type inverter considering power devices and capacitors under different clamping periods. 40
Fig. 3.15. B10 lifetime of T-type inverter under different clamping periods.[이미지참조] 40
Fig. 4.1. reference voltages and pole voltages under different clamping periods (a) 0°, (b) 60°and (c) 180°. 42
Fig. 4.2. Output current and output voltage in the time and frequency domain under different clamping periods (a) 0°,(b) 60, (c) 110°and (d) 180° 43
Fig. 4.3. FFT of the neutral-point current under different clamping periods (a) 0°, (b) 60°and (c) 180° 45
Fig. 4.4. Efficiency comparison of T-type inverter at 2kW with: (a) UP-PWM and (b) DPWM (θ=180°). 46