PURPOSE: To improve vibration and noise of a motor by dividing one excitation phase into a plurality of subsections and switching the comparison resistor of a constant voltage circuit.
CONSTITUTION: An I/O port is provided with output ports S1, S2 for setting a voltage level wherein the output ports S1, S2 are switched four times within one pulse time such that the S1, S2 are turned OFF for the first quarter pulse. Consequently, phase A has a level output of 1 and phase B has a level output of 4. When the S1 is turned ON whereas the S2 is turned OFF for the second quarter pulse, phase A and phase B have a level output of 2. The S1, S2 are kept in previous state for the third quarter pulse and thereby the same level outputs are sustained. For the final quarter pulse, the S1 and S2 are turned ON and phase A has a level 4 whereas phase B has a level 1. Since a smooth current waveform is ensured from low speed region to high speed region, vibration and noise of a motor can be improved.
HIRAMATSU SOICHI
NAKAMURA HITOSHI
INOUE HIROYUKI
YAMAGUCHI HIDEKI
KIDA AKIRA
KAWAKAMI HIDEAKI
IWASAKI TAKESHI
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