US 2006/0214624 A1 · Electric motor drive

Abstract

The invention relates to an electric motor drive for operating an alternating-current motor. The electric motor drive comprises a frequency converter for controlling the motor, which frequency converter comprises a rectifier and an inverter implemented using semiconductor switches arranged in a bridge, and an intermediate circuit placed between the rectifier and the inverter and comprising a capacitor. According to the invention, the electric motor drive additionally comprises two regulating units, the first one of which contains an inductor unit provided at the input of the frequency converter and at the same time at the input of the rectifier, the inductors comprised in the unit being connected to each phase; and an intermediate circuit with a low-value capacitor, of the order of 50 μF, while the second one contains an auxiliary switch, to which the supply of electric power is arranged to occur via a safety relay, the auxiliary switch being so connected to selected semiconductor switches of the inverter bridge that the control signal for a selected semiconductor switch will pass via the auxiliary switch when the latter is in a conducting state; and a current measuring unit for measuring and/or monitoring the supply current to the electric motor.

Claims23

Dependent claims

An electric motor drive for driving an alternating-current motor comprising:

a frequency converter for controlling the electric motor, wherein the frequency converter comprises a rectifier and an inverter;
an intermediate circuit connecting an output of the rectifier and an input of the inverter for reducing the surge current from the power source;
and
a current measuring unit, in a three-phase network, measuring or monitoring a three-phase current to the electric motor;
wherein the inverter includes,
a plurality of inverter contactless switches for controlling the conduction of current for supply to the electric motor, and
an auxiliary switch connected to selected ones of said inverter contactless switches,
a control input to said auxiliary switches supplied by a safety device, the safety device disabling said inverter contactless switches by controlling the conduction of said auxiliary switches so that supply of current to the electric motor by said inverter may be disabled by said safety device.

5 more elements

An electric motor drive for driving an alternating-current motor comprising:

a frequency converter for controlling the electric motor, wherein the frequency converter comprises a rectifier and an inverter;
an inductor unit, in a three-phase network, connecting an alternating-current power source to an input of the frequency converter to an input of the rectifier for reducing a surge current from the alternating current power source;
an intermediate circuit connecting an output of the rectifier and an input of the inverter for further reducing the surge current from the power source;
and
a current measuring unit, in a three-phase network, measuring or monitoring a three-phase current to the electric motor;
wherein the inverter includes an auxiliary switch that is connected to selected semiconductor switches, to which the supply of electric power is arranged to occur via a safety relay, said auxiliary switch being se connected to the semiconductor switches of said inverter so that a control signal for said semiconductor switches will pass via the auxiliary switch when the auxiliary switch is in a conducting state;
wherein the semiconductor switches of the inverter are arranged in a pair of bridges and only one bridge includes at least one auxiliary switch.

4 more elements

Dependencies are inferred from the claim text.

Electric motor drive

Life of this patent

Electric motor drive

Life of this patent

Abstract

Claims23