| 摘要 |
During start-up a telegraph-start circuit for a DC motor withholds exciting current from the stator field coils during alternative ones of the polyphase commutation signals used when the motor is running. This produces a high starting torque at an initial time overcoming dead-point, head-sticking and insufficient-initial-starting-torque problems in motor drive applications, while avoiding rail-to-rail short-through problems in the driver circuitry. Commutation-stop and power-OFF time control lowers dissipation required of field coil driver circuitry by periodically interrupting starting current flow into the DC motor field coils. The telegraph-start circuit includes an adjustable-rate clock generator, a commutation-stop and power-OFF time controller, a ring counter, a dual-mode commutation circuit, field coil driver circuitry, a zero-crossing reference generator, a phase selector, a zero-crossing detector, and a condition-of-rotation detector.
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