Patent ID: 6121736
Filing Date: 2000-09-19
Classification: H02P

Abstract:
A motor control apparatus comprising:an upper switching element group having a plurality of switching elements which form current paths to coils of respective phases of a motor;a lower switching element group having a plurality of switching elements which form current paths from said coils of a respective phases of said motor;a plurality of diodes, each said diode being connected in reverse parallel with a corresponding one of said switching elements of said upper and lower switching element groups;switching element modulation means for providing a conduction/cut-off signal to said upper and lower switching element groups thereby to cause switching elements of the same phase to perform a switching action so that said switching elements conduct or are cut off with the provision of a simultaneous cut-off period, for the application of voltages to said coils of said respective phases of said motor;voltage output means for detecting terminal voltage values of said coils of said respective phases connected between said switching elements of respective phases in said upper and lower switching element groups, and for providing said detected terminal voltage values;at least one current sign change detection means for detecting, from said conduction/cut-off signal of said switching element modulation means and said terminal voltage values detected by said voltage output means, a timing of the sign change of a phase current, and for providing a current sign change timing signal; andfirst applied voltage control means for issuing, based on said current sign change timing signal and applied voltage values of said coils of said respective phases, a phase applied voltage command to said switching element modulation means.