Electric motor drive
First Claim
1. 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 the alternating-current power source to an input of the frequency converter to an input of the rectifier for reducing a surge current from a 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 and/or monitoring a three-phase current to the electric motor.
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Accused Products
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 electric motor, that includes a rectifier and an inverter implemented using semiconductor switches arranged in a bridge, and an intermediate circuit comprising a capacitor and placed between the rectifier and the inverter. The electric motor drive additionally comprises two regulating units. The first regulating unit contains an inductor unit at the input of the frequency converter and at the input of the rectifier, where the inductors comprised in the unit being connected to each phase; and an intermediate circuit with a low-value capacitor of 50 μF. The second regulating unit comprises an auxiliary switch, to which the supply of electric power is arranged to occur via a safety relay and a current measuring unit. The auxiliary switch is connected to each semiconductor switch of the inverter bridge in which the control signal for each semiconductor switch will pass via the auxiliary switch when the auxiliary switch is in a conducting state. The current measuring unit measures and/or monitors the supply current to the electric motor.
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Citations
14 Claims
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1. An electric motor drive for driving an alternating-current motor comprising:
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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 the alternating-current power source to an input of the frequency converter to an input of the rectifier for reducing a surge current from a 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 and/or monitoring a three-phase current to the electric motor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for driving an alternating-current motor in an electric motor drive comprising:
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controlling the electric motor in a frequency converter;
connecting the alternating-current power source to the input of an inductor in a three-phase network unit for reducing a surge current in a power source;
connecting a rectifier and inverter in the frequency converter for further reducing a surge current in the power source; and
measuring and/or monitoring a three-phase current to the electric motor. - View Dependent Claims (11, 12, 13, 14)
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Specification