Patent ID: 7019484
Filing Date: 2006-03-28
Classification: H02P

Abstract:
1. A stepping motor driver which supplies sinusoidally varying exciting currents to a stepping motor each time an external command pulse is applied, said stepping motor driver comprising: (a) an excitation angle generating means for generating an excitation angle from said external command pulse; (b) a current control means for controlling said exciting currents according to said excitation angle and a current command; (c) a current detection means for detecting phase currents of said stepping motor; (d) an angle detection means for detecting a rotor rotation angle of said stepping motor; (e) a torque component current calculating means for calculating a torque component current from said phase currents and said rotor rotation angle; (f) an absolute value converting means for obtaining an absolute value of said torque component current; (g) a high speed-response judging means adapted for outputting a first control signal when a speed deviation between a command speed and a rotor speed is not more than a reference level, and outputting a second control signal when said speed deviation exceeds said reference level; and (h) a current command outputting means adapted for outputting said current command according to said absolute value of said torque component current when said first control signal is outputted from said high speed-response judging means, and outputting a maximum current command value as said current command when said second control signal is outputted from said high speed-response judging means.