Examens De Fin Module Semi-Conducteurs Électromécanique des Systèmes Automatisées-ESA-OFPPT-PDF

Examens De Fin Module Semi-Conducteurs Électromécanique des Systèmes Automatisées-ESA-OFPPT-PDF

Examens De Fin Module Semi-Conducteurs

 ESA-OFPPT-PDF

Presentation

The throb of the rotor of an asynchronous motor is:

w = ws (1-g)

with

g: slip

p: number of pairs of poles

: rotor throb (in rd / s)

s: synchronism throb (in rd / s)

f: strain frequency (Hz)

: strain throb (rd / s)

The adjustment of the engine revolution speed can therefore be obtained as standard:

Activity on the number of pairs of poles

• extraordinary primary winding machines (coupling of Dahlander type windings)

• machines with several primary windings (machines with separate windings)

Activity on the frequency of the stator feed strain

• electromechanical frequency converters (large alternator driving several asynchronous motors running at the same speed)

• static converters (current, strain, M.L.I inverters, transition vector control, cycloconverters)

Activity on sliding

• action on the stator supply strain (autotransformer, dimmer)

• rotor slip rheostat

• recovery cascade (hyposynchronous stroke)

Separate winding motor

It is the assembly of two motors having different speeds and torques

The size is in addition to significant, but the speed affinity can be different from 2

Activity on the frequency of the stator strain

The static converter type "inverter" allows engine operation with maximum torque, standard simultaneous activity on the frequency and on the amplitude of the stator strain, with protection of affinity U / f

The converter R varies the value of the strain Ur. The converter O changes the frequency of the stator pressure. The capacitors block the thyristors. The diodes prevent the capacitors from discharging during the motor stages. A dainty inductance in series with each thyristor limits the di / dt. The current flowing in the inductor L is strongly smoothed.

The inversion of the thyristor control sequence allows the reversal of the direction of revolution of the motor. Standard regenerative braking takes place when the motor pivot frequency is greater than the synchronization frequency: O then operates as a rectifier and R as an assisted inverter.

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