A method of operating an implantable blood pump having a first stator, a second stator, and an impeller movably disposed there between. The method includes applying a first voltage waveform at first phase to the first stator to generate a magnetic field to rotate the impeller. A second voltage waveform is applied at a second phase shifted from the first phase to the second stator to rotate the impeller, the second voltage waveform is asymmetric to the first voltage waveform.