Driving device comprising a converter and a synchronous motor with permanent-magnet excitation fed by said converter

摘要

1. A controllable speed driving device comprising a converter and a synchronous motor with permanent-magnet excitation. 2.1 As is known, the pole-wheel voltage induced in the armature winding by the permanent magnets increases with speed and it is thus normal also to allow the output voltage of the converter to increase with speed, the current taken by the synchronous motor being reduced accordingly. With the maximum power of the synchronous motor being constant, at the minimum speed of the controllable speed range the apparent power occurring is thus equal to the product Umin x Imax and at the maximum speed it is equal to the product Umax x Imin. Since the converter must be able to supply both the maximum voltage Umax and the maximum current Imax, its rated power is equal to the product Umax x Imax. The rated power of the converter is thus significantly greater than the maximum power of the synchronous motor. In the case of the new driving device, the rated power of the converter is intended to have a value which is as close as possible to the maximum power with respect to the maximum power of the synchronous motor in the operational speed range. 2.2 The converter (11) is operated at a constant output voltage in the operational speed range (nu, no), and the inductances acting in the circuit of the synchronous motor (12) are dimensioned such that, at the maximum power of the synchronous motor, the currents (Iu, Io) at the output of the converter are of equal magnitude both at the lowest and at the highest speed (nu, no). 2.3 Speed-controllable drives with permanent-magnet excited synchronous motors. IMAGE