초록 ▼

Dynamic operation of a brushless N-phase DC motor results in a high torque constant (Kt) line-to-line phase configuration during spindle motor power-up, and in a lower effective Kt configuration once normal run speed operation is attained. When the spindle motor is rotating below a predetermined run

Dynamic operation of a brushless N-phase DC motor results in a high torque constant (Kt) line-to-line phase configuration during spindle motor power-up, and in a lower effective Kt configuration once normal run speed operation is attained. When the spindle motor is rotating below a predetermined run speed, drive transistors coupled to the motor phases cause at least two phases to be series-coupled between the source of operating voltage and ground. This ensures a large initial torque because the Kt contribution of each series-coupled phase is combined vectorially. Once run speed is achieved, effective Kt is lowered by causing the drive transistors to energize but a single phase, reconfiguring the spindle motor for line-to-neutral operation. So doing reduces the effective back electromagnetic force, permitting sufficient run current from a given magnitude operating voltage source. The present invention permits designing the spindle motor Kt for line-to-neutral normal run speed conditions, while ensuring a large start-up Kt by starting the motor line-to-line.

대표청구항 ▼

A method for dynamic operation of a brushless N-phase DC motor, where N≥3, wherein a first end of each phase is coupled to a source of operating voltage or ground by an associated drive switch, and each second end of each said phase is coupled via a mode switch to said source of operating voltage, c

A method for dynamic operation of a brushless N-phase DC motor, where N≥3, wherein a first end of each phase is coupled to a source of operating voltage or ground by an associated drive switch, and each second end of each said phase is coupled via a mode switch to said source of operating voltage, comprising the following steps: (a) determining rotational speed of said motor by examination of back electromotive force generated by said motor; (b) when said motor has a rotational speed less than a predetermined run velocity, configuring said motor in line-to-line mode by series-coupling at least two of said N-phases to a source of operating voltage; (c) when said motor has a rotational speed at least equal to said predetermined run velocity, configuring said motor in line-to-neutral mode by coupling fewer than two of said N-phases to said source of operating voltage; and (d) configuring said motor between step (a) and step (b) by selectively changing the state of said mode switch and at least a chosen one of said drive switches.