Confidential and Proprietary Information of Fluxtrol, Inc. Auburn Hills, MI Simulation of Induction System for Brazing of Squirrel Cage Rotor Dr. Valentin Nemkov (1) , Dr. Valentin Vologdin (2) Dr. Vl. Vologdin Jr. (2) , Kevin Kreter (1) (1) Fluxtrol, Inc., USA; (2) Freal, Ltd., Russia Padua, Italy, May 21- 24, 2013
15
Embed
SIMULATION OF INDUCTION SYSTEM FOR BRAZING OF SQUIRREL CAGE ROTOR
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Confidential and Proprietary Information of Fluxtrol, Inc. Auburn Hills, MI
Simulation of Induction System for Brazing of Squirrel Cage Rotor
Dr. Valentin Nemkov(1), Dr. Valentin Vologdin(2)
Dr. Vl. Vologdin Jr. (2), Kevin Kreter(1) (1)Fluxtrol, Inc., USA; (2)Freal, Ltd., Russia
Padua, Italy, May 21-24, 2013
Specs and System Description • Copper ring must be heated up to temperature 800-850 C• Single-turn coil has П-shaped concentrator made of Fluxtrol LRM • Concentrator is attached to the coil with a thermally conductive
glue, k = 0.01 W/cmK• Ceramic fiber insulation pad between the coil and ring has
thermal conductivity k = 0.002 W/cmK; thickness of pad is 2 mm• Motor bars are substituted for a tube filling the whole groove;
thermal conductivity and heat capacity of the tube reduced by space factor g = 0.42
• Simulation was made at a constant coil voltage corresponding to mean power equal to 50 or 75 kW during the heating time
• Program Flux 2D has been used for simulation
Brazing Setup and Joint Cross-section
№ Rotor type
D1,
mmD25, mm D21, mm D22, mm D23, mm D24, mm h, mm H2, mm
1 АDТ-3 170 151 155 211 165 206 14 348
2 DТА-1 242 223 222 298 243 294 20 500
Case 1
Temperature at Braze Joint
0 50 100 150 2000
100
200
300
400
500
600
700
800
900
3 kHz
50 kHz
Time (s)
Temperature(C)
Case 1, 50 kW
Study was made for two rotor sizes (case 1 and case 2), two levels of frequency (3 kHz and 50 kHz) and two levels of power (50 and 75 kW)
Temperature profiles are almost the same for 3 kHz and 50 kHz
0 50 100 150 200 250 3000
100
200
300
400
500
600
700
800
900
1000
3 kHz50 kHz
Time (s)
Temperature(C)
Temperature at Braze Joint
Case 2, 75 kW
Coil Thermal Profile at the End of the Process
Case 2, 50 kHz, 75 kWTmax = 200 0C
Case 2, 3 kHz, 75 kWTmax = 190 0C
Tmax of concentrator is close to upper limit for Fluxtrol material and must be kept under control by material selection, concentrator design and proper manufacturing.
Intensive coil cooling is required
Simulated and Experimental Process Parameters
Rotor type
Power, kW Frequency kHz Time sec NotePtotal Pcoil Pring Pмagn
АТD-3Case 1
50 22.8 26.7 0.5 50 185 Model (Case 1)
50 - - - 54 170 Experiment
50 23.6 26.2 0.2 3 205 Model (Case 1)
DТА-1Case 2
50 21.6 28.1 0.3 50 925 Model (Case 2)
50 - - - 46 930 Experiment
75 34 40.6 0.4 50 310 Model (Case 2)
75 35 39.8 0.2 3 335 Model (Case 2)
0 50 100 150 200 250 3000
50
100
150
200
250
300
3 kHz50 kHz
Time (s)
Axial Force on Ring
(N)
Electrodynamic Forces on Ring
75 kW
Forces are rather high especially at 3 kHz. They can cause vibration and noise
End of Test Brazing Process
Operator controls brazing quality and adds solder when required
Red spot in the circle shows a point of the temperature control using laser aiming
Conclusions• 2D simulation gives accurate enough results despite several assumptions
• Frequency variation in the wide range from 3 to 50 kHz does not influence the process efficiency and temperature distribution much
• The use of frequency below 8 kHz may be limited by forces and noise
• The use of the higher range of frequency may be limited by high coil voltage and elevated temperature of SMC concentrator
• Optimal frequency for the studied rotors is in a range of 10-30 kHz
• Process is sensitive to a minimum power level. Brazing of rotor no. 2 at 50 kW is marginal. Heating time is almost triple compared to 75 kW
• Simulation and experiments showed that SMC concentrators may be effectively used in rotor brazing
• Computer simulation may be used as a powerful tool for design of rotor brazing processes