Patent ID: 8143826
Filing Date: 2012-03-27
Classification: H01M,H02P,Y02B,Y02E

Abstract:
1. A drive control circuit for an electric motor, the drive control circuit comprising: an original drive signal generator that generates an original signal based on a positional signal, wherein the positional signal indicates a relative position of a first drive member of the electric motor and a second drive member of the electric motor; an excitation ratio signal generator that generates an excitation ratio signal based on a speed signal, wherein the speed signal indicates a relative speed of the first drive member and the second drive member, and wherein the excitation ratio signal indicates a ratio of excitation interval to non-excitation interval of coils of the electric motor; an excitation interval signal generator that generates a binary excitation interval signal based on the positional signal and the excitation ratio signal, wherein the excitation interval signal specifies either the excitation interval or the non-excitation interval; and a mask circuit that generates a drive signal by masking part of the original drive signal based on the excitation interval signal, wherein; the drive signal drives the electric motor; the mask circuit outputs the original drive signal as the drive signal only when the excitation interval signal specifies the excitation interval; the excitation ratio signal generator, at startup of the electric motor, sets the excitation ratio signal such that the excitation interval is a predetermined maximum value; the excitation ratio signal generator, subsequent to startup of the electric motor, sets the excitation ratio signal such that the excitation interval becomes shorter as the relative speed indicated by the speed signal increases; the speed signal includes a cyclical binary timing signal synchronized with the positional signal; and the excitation ratio signal generator includes: