Method and device for operating an electric motor
AssigneeWoehner GmbH & Co. KG Elektrotechnische Systeme
InventorsPhilipp Steinberger, Daniel Steiner, Hubert Lenker
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Abstract
Device for operating an electric motor, comprising a detection unit for detecting zero-crossings and phase angles of applied phase-shifted sinusoidal voltage phases of a multi-phase power supply network; and a switching unit for connecting half-waves of the applied sinusoidal voltage phases through by means of semiconductor switches in accordance with switching patterns applied to the semiconductor switches, said patterns being synchronised with the detected phase angles and zero-crossings, to generate phase-shifted quasi-sinusoidal voltage phases which are applied directly to the electric motor.
Claims21
Method for operating an electric motor, comprising the steps of:
- (a) detecting zero-crossings and phase angles of applied phase-shifted sinusoidal voltage phases of a multi-phase power supply network;
- and
- (b) connecting half-waves of the applied sinusoidal voltage phases by means of semiconductor switches in accordance with switching patterns applied to the semiconductor switches, said patterns being synchronised with the detected phase angles and zero-crossings, to generate phase-shifted quasi-sinusoidal voltage phases which are applied directly to the electric motor, wherein to start up the electric motor the frequency of the quasi-sinusoidal voltage phases is stepped up incrementally by changing the switching patterns applied to the semiconductor circuits until the network frequency of the voltage supply network is reached, wherein after the network frequency of the power supply network is reached the electric motor is supplied directly by the power supply network, via mechanical contacts connected in parallel with the semiconductor switches.
Device for operating an electric motor, comprising:
- a detection unit for detecting zero-crossings and phase angles of applied phase-shifted sinusoidal voltage phases of a multi-phase power supply network;
- and
- a switching unit for connecting half-waves of the applied sinusoidal voltage phases by means of semiconductor switches in accordance with switching patterns applied to the semiconductor switches, said patterns being synchronised with the detected phase angles and zero-crossings, to generate phase-shifted quasi-sinusoidal voltage phases which are applied directly to the electric motor, wherein the switching unit is a hybrid switching unit, which has mechanical contacts which are connected in parallel with the semiconductor switches of the switching unit,
- wherein a control unit is provided which is configured and operable to actuate semiconductor switches of the switching unit in accordance with the switching patterns read out from a data store,
- wherein to start up the electric motor the frequency of the quasi-sinusoidal voltage phases is stepped up incrementally by the switching unit by operation of the control unit changing the switching patterns applied to the semiconductor circuits until the network frequency of the voltage supply network is reached, wherein after the network frequency of the power supply network is reached the electric motor is supplied directly by the power supply network, via mechanical contacts connected in parallel with the semiconductor switches.
Dependencies are inferred from the claim text.