Method for diagnosing a frequency converter
AssigneeDr. Johannes Heidenhain GmbH
InventorsFranz Ritz, Norbert Huber
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Abstract
A method for diagnosing a frequency converter is used for a frequency converter having a positive and negative DC link voltage which is applied via bridges of switching elements in an alternating sequence to phases of a motor. Pulse width modulation (PWM) signals drive the switching elements for a respective one of the phases and current sensors capture phase currents. In a step a), PWM signals are applied as test patterns to the switching elements. In a step b), sensor signals of the current current sensors are picked up. In a step c), the sensor signals are evaluated by ascertaining a presence of the DC link voltage upon a displacement current being recognized in the sensor signals.
Claims5
A method for diagnosing a frequency converter, the frequency converter having a positive and negative DC link voltage which is applied via bridges of switching elements in an alternating sequence to phases of a motor, wherein pulse width modulation (PWM) signals drive the switching elements for a respective one of the phases, and wherein current sensors capture phase currents, the method comprising:
- a) applying PWM signals as test patterns to the switching elements;
- b) picking up sensor signals of the current sensors;
- and
- c) ascertaining a presence of the DC link voltage upon a displacement current being recognized in the sensor signals at each of the flanks of the PWM signals applied as the test patterns, the displacement current being recognized by detecting discrete current spikes occurring in the sensor signals and determining whether each respective one of the current spikes temporally coincides with each respective one of the flanks of the test patterns.
Dependencies are inferred from the claim text.