A current detection method for an electric motor which detects phase currents
of
the electric motor driven by a power converter that provides ON/OFF control of
bridge-connected switching elements, based on a pulse-width modulation excitation
pattern, to convert a direct current into poly-phase alternating currents. The
method includes connecting a current detecting element which produces a signal
corresponding to a current value at the direct current side of the power converter
and changing the pulse-width modulation excitation pattern by executing a shift
of time of any of the phases of the pulse-width modulation excitation pattern so
that a signal directly or indirectly corresponding to the phase currents is produced
at the current detecting element. The method also includes detecting the phase
currents of the electric motor based on the signal produced at the current detecting
element and the excitation pattern which has been changed.
