Patent ID: 11860003
Assignee: NIDEC CORPORATION
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 3:
4. The signal processing device of claim 1, wherein,
the preprocessing circuit performs a correction step selected from among a first correction step, a second correction step, and a third correction step to generate the corrected detection signals;
the first correction step comprises
consecutively selecting one of the detection signals, and subtracting a mean value of the other unselected detection signals from the selected detection signal, thereby correcting the selected detection signal to generate the corrected detection signal;
the second correction step comprises,
for the detection signal of each phase, detecting a local maximum and a local minimum for a respective pole pair and a maximum amplitude value and a minimum amplitude value per cycle of electrical angle, over the course of at least two cycles,
for the detection signal of each phase, calculating in the correction section a mean of the maximum amplitude values and a mean of the minimum amplitude values,
determining an offset correction value to be a maximum-minimum mean value which is calculated from the mean of the maximum amplitude values and the mean of the minimum amplitude values,
for each detection signal, calculating a positive gain correction value for a respective magnetic pole pair that equates the local maximum with a predetermined maximum value,
for the detection signal of each phase, calculating a negative gain correction value for a respective magnetic pole pair that equates the local minimum with a predetermined minimum value, and
for the detection signal of each phase, adding the offset correction value, multiplying a positive signal value from a respective magnetic pole pair with the positive gain correction value, and multiplying a negative signal value from a respective magnetic pole pair with the negative gain correction value; and
the third correction step comprises
multiplying each detection signal with a predetermined coefficient based on a waveform state of the detection signal.