| 摘要 |
PURPOSE:To eliminate the generated torque of each phase when the current instruction of each phase is zero by a method wherein currents are not applied to the exciting coils of respective phases if the current instructions of those phases are not higher than a predetermined level. CONSTITUTION:When the current instructions of respective phases are not higher than a predetermined level, a control circuit 10 have control signals Sa, Sb and Sc corresponding to those phases on an L-level. Corresponding AND- gates 12a1 and 12a2. AND-gates 12b1 and 12b2 and AND-gates 12c1 and 12c2 are closed. PWM signals of the phases whose current instructions are not higher than the predetermined level are not outputted from the AND-gates. As all the switching devices Ta1-Ta4, switching devices Tb1-Tb4 and switching devices Tc1-Tc4 of those phases are turned OFF, currents are not applied to exciting coil 13a, exciting coil 13b and exciting coil 13c. A setting time for that can be shorter and an interference torque can be avoided. |
