Invention Grant

Motor drive
Abstract:
A motor drive includes a rectifier bridge for connection with mains, a converter bridge configured to connect with an elevator motor and an intermediate DC circuit in-between. A capacitor and/or battery is connected between positive and negative branches of the intermediate DC circuit. At the mains side of the rectifier bridge a controlled main relay with contacts are configured to connect or disconnect the rectifier bridge with the corresponding mains phase. The motor drive comprises a charging circuit which comprises a charging switch connected with a current limiting component. The motor drive comprises a voltage sensor between positive and negative branches of the intermediate DC circuit. The voltage sensor is connected to a circuit comprising a reference value and a comparator. The evaluation circuit is configured to compare the actual sensor signal of the voltage sensor to the reference value and to operate the main relay based on the comparison.
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