| 摘要 |
The invention relates to an electric motor drive for operating an alternating-current motor (10). The electric motor drive comprises a frequency converter (6) for controlling the motor, which frequency converter (6) comprises a rectifier (61) and an inverter (62) implemented using semiconductor switches arranged in a bridge, and an intermediate circuit (63) placed between the rectifier and the inverter and comprising a capacitor (63a). According to the invention, the electric motor drive additionally comprises two regulating units, the first one of which contains an inductor unit (7) provided at the input of the frequency converter (6) and at the same time at the input of the rectifier, the inductors (7<1>, 7<2>; 7<3>) comprised in the unit being connected to each phase (R, S, T); and an intermediate circuit (63) with a low-value capacitor, of the order of 50 muF, while the second one contains an auxiliary switch (13), to which the supply of electric power is arranged to occur via a safety relay (9), said auxiliary switch being so connected to each semiconductor switch (12) of the inverter bridge (62) that the control signal for each semiconductor switch will pass via the auxiliary switch when the latter is in a conducting state; and a current measuring unit (8) for measuring and/or monitoring the supply current to the electric motor.
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