| 摘要 |
An uninterrupted power source (UPS) system is provided by utilizing a synchronous motor to power an alternator which provides the desired uninterrupted output power. Normally, the synchronous motor is powered by utility line power. However, an interruption in utility power will cause the motor-alternator set to slow down, although the inertia of the system will continue generating power. If the utility power interruption is sufficient such that the alternator output frequency drops more than 1 Hz, or if reverse power flow is detected from the synchronizing motor back into the utility grid, the motor is automatically powered by an inverter driven from a battery-powered current source. A feedback system from the alternator output insures that the inverter is synchronized with the synchronous motor in order to quickly bring the alternator's output back up to the desired voltage and frequency level. A phase locked loop is utilized to bring the alternator output frequency into phase with a crystal oscillator generating a 60 Hz reference. Upon reapplication of utility line power, the inverter control system adjusts the phase of the motor alternator to the utility line power before reconnecting the motor directly to the utility power system, preventing large current and torque excursions and maintaining an extremely stable alternator output during any and all utility line power interruptions.
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