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ON THE STEADY-STATE PERFORMANCE OF A TRANSISTORIZED PWM INVERTER INDUCTION MOTOR DRIVE SYSTEM FOR HIGH SPEED
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| Author(s) |
E. Ch. Andresen; A. Schindler |
| Abstract |
A specially designed high speed drive system consisting of a 3-phase a.c. squirrel cage induction motor and a transistorized PWM frequency inverter is presented. The motor power output is 10 kW at rated pole flux, 400 Hz stator frequency and 12000 r.p.m. The inverter is rated for 15 kVA, 400 V and 37 A. The pulse width modulation works in the two-step mode with constant frequency adjustable from 1,25 to 20kHz in 16 steps. Harmonic analysis reveals that the amplitudes of the motor phase voltages get minimum when timing the pulse periods of the three inverter phases without phase shift. Though generating single phase MMF waves in addition to three phase MMF waves this mode causes the smallest harmonic effects in the machine. Computer simulation shows that mechanical resonance oscillations (393 Hz) are excited when operating the inverter with low pulse frequencies and that oscillations disappear at high frequencies. The measured additional losses of the motor (10 to 18 % of the rated power output) are approximately halved through changing the modulation frequency from 1,25 to 10 kHz. A study of the calculated loss components shows that the additional losses can be decreased only little by increasing the leakage inductances and by applying laminations with very low magnetiziation losses. |
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| Filename: | Unnamed file |
| Filesize: | 2.948 MB |
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| Type |
Members Only |
| Date |
Last modified 2021-03-11 by System |
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