FLUX를활용한몰드변압기의전기적손실계산과열해석을통한 Hot-spot 확인

산일전기김선영선임연구원

Finding hotspot of Molded transformer through the electric losses and thermal analysis

목적및모델선정

TECHNICAL DATA

No. of phase (Ph) 3

Rated power (kVA) 7,000

Rated frequency (Hz) 60

Rated Voltage (No-load)

Pri.Winding (V) 11,000

Sec.Winding (V) 2 x 1,850

Winding material Pri.Winding Aluminum

Sec.Winding Aluminum

▪ 해석대상변압기사양

▪ 목적

➢ 코일외에주변도체의전기적손실계산필요

➢ 변압기개발시온도특성검토필요

해석과정

FLUX 2D (자계)winding eddy current

FLUX 3D (자계)structure

Acusolve(CFD)Convection coefficient

FLUX(열계)Hot-spot 확인

전기적손실합계

Heated Air Outlets

Cooling Air Inlets

Joule Special Short Circuit

Losses

HV 13917 3111 17028

LV delta 10743 3897 14640

LV star 10683 3291 13974

Connections HV 159 1 160

Connections LV delta 280 38 318

Connections LV star 808 105 913

Steel 0 35 35

Tank 0 40 40

Total 36590 10518 47108

Enclosure

FLUX 2D(자계)-Eddy Current Losses analysis

Unit |W] JOULE EDDY

HV LOSSES 1 296 194

HV LOSSES 2 296 70

HV LOSSES 3 303 31

HV LOSSES 4 239 17

HV LOSSES 5 249 25

HV LOSSES 6 312 41

HV LOSSES 7 312 34

HV LOSSES 8 312 105

HV TOP TOTAL 2320 518

HV LOSSES 8 312 105

HV LOSSES 7 312 35

HV LOSSES 6 312 41

HV LOSSES 5 249 25

HV LOSSES 4 239 17

HV LOSSES 3 303 31

HV LOSSES 2 296 70

HV LOSSES 1 296 195

HV BOTTOM TOTAL 2320 519

LV TOP TOTAL 3581 1299

LV BOTTOM TOTAL 3561 1097

HV 1Phase 5677

LV 1Phase 9538

1Phase Tot. 15215

HV 3Phase 17031

LV 3Phase 28614

3Phase TOTAL 45645

▪ Current density in connection and structure [A/cm2]

JouleEddy current

losses

Short Circuit

Losses

Connections

HV159 1 160

Connections

LV delta280 38 318

Connections

LV star808 105 913

Steel 0 35 35

Tank 0 40 40

Total 1247 219 1466

FLUX 3D(자계)-Stray Losses analysis

Acusolve(CFD)-convection coefficient contours

Acusolve(CFD)-convection coefficient analysis

A Phase B Phase

1HV_top

Outer 23.55 16.67

Inner 59.51 59.16

2HV_bot

Outer 30.55 24.9

Inner 32.94 34.10

3LV_top

Outer 58.77 61.63

Inner 49.94 47.71

4LV_bot

Outer 32.65 34.48

Inner 45.57 42.39

[W/m2K]

FLUX 2D(열계) – Hot-spot Analysis

▪ AFWF type

Hot point

Winding Temperature

HV_top 78.0 ℃

HV_bottom 80.3 ℃

LV_top 73.5 ℃

LV_bottom 73.4 ℃

SUMMARY

▪ 전기적손실계산(Eddy current losses + Stray losses)

- FLUX2D를활용하여 axisymmetry model로권선도체각각의손실을계산하고 FLUX3D를활용하여부스바와코어지지

대, 탱크에서발생하는 stray loss를계산하였다.

Joule Special Short Circuit

Losses

2D eddy current losses

HV 13920 3111 17031

LV delta 10743 3897 14640

LV star 10683 3291 13974

3D stray losses

Connections HV 159 1 160

Connections LV delta 280 38 318

Connections LV star 808 105 913

Steel 0 35 35

Tank 0 40 40

Total 36593 10518 47111

▪ Hot-spot 확인(Winding losses + CFD + Thermal)

- FLUX2D 자계해석으로권선도체각각의단위면적당손실을계산하고 Acusolve를활용하여코일표면에발생하는대류

상수를계산하였다.

- FLUX2D 열계해석을사용하여자계해석으로얻은 Heat source와 CFD로얻은대류상수를사용하여코일내부의 hot-spot

이하부 HV코일에서 80℃의 최고온도를보이는것을확인하였다.