| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a rotational speed calculation device capable of accurately calculating rotational speed of a rotor during low rotation. <P>SOLUTION: A method for calculating rotational speed N of a rotor 70 is made different at a point of time for calculating the rotational speed N in this time by depending on whether or not a pulse interval T[0] between a pulse at the time before the last time and a pulse in the last time is larger than a time interval Tc between the pulse in the last time and a point of time for calculating the rotational speed N in this time when pulses are not generated between a point of time for calculating the rotational speed N in the last time and a point of time for calculating the rotational speed N in this time. Even when pulses are not generated, the rotational speed N of the rotor 70 is calculated by an optimum calculation method by depending on whether or not the time interval Tc from the pulse in the last time to the point of time for calculating the rotational speed N in this time is larger than the pulse interval T[0], and the rotational speed N can be accurately calculated. <P>COPYRIGHT: (C)2012,JPO&INPIT |
