US Patent 7932691 Permanent magnet motor start-up

Methods and apparatus are provided for startup of a permanent magnet alternating current (AC) motor. The method comprises the steps of detecting startup of the permanent magnet AC motor; detecting a mechanical oscillation of the permanent magnet AC motor when startup of the permanent magnet AC motor is detected; and, in response to detection of the mechanical oscillation of the permanent magnet AC motor when startup is detected, suppressing the mechanical oscillation of the permanent magnet AC motor.