| 摘要 |
PURPOSE: To reduce the mechanical shock on a stepping motor, when turned on, by changing each phase current of the stepping motor gently from an initial power-on value to a current based on initial-value continuity sequence. CONSTITUTION: In a three-phase full bridge inverter 11, a connection point between transistors Q1 and Q2 is connected to a u-phase of a stepping motor 10, a connection point between transistors Q3 and Q4 is to a v-phase, and a connection point between transistors Q5 and Q6 to a w-phase thereof. When a power switch 15 is turned on, a DC current is fed to the three-phase full bridge inverter 11 through a power rectifier 14, and a power-on detection signal is generated by a power detector 16 to an initial current control unit 17. The initial current control unit 17 generates a signal to a PWM pattern generator 12 to control each phase current in windings of the stepping motor 10 in a way that the each phase current changes from an initial power-on value gently to a current value based on initial-value sequence. |
