| 摘要 |
PROBLEM TO BE SOLVED: To detect an open phase in a three-phase power source by an inexpensive method which does not need an exclusive circuit. SOLUTION: This open-phase detector is equipped with a rectifier which rectifies three-phase AC power into DC voltage, a smoother which smoothes the DC voltage rectified in the above rectifier, an inverter which uses the smoothed DC voltage as a power source, a three-phase motor which is driven by the above inverter, a voltage detecting means which detects the smoothed DC voltage, and a controller which calculates the amount of ripple of the voltage detected by the above voltage detecting means. In case that the amount of ripple detected by the controller is at or over a given value within a given time after start of the above three-phase motor, this determines it to be open-phase, and issues a stop signal to the above inverter by the above controller so as to stop the above three-phase motor. Hereby, in case that the open phase occurs, this detects the open phase quickly, and takes a protective action to the inverter, whereby this can avoid something wrong such as the damage or the like of the controller caused by the operation in an open-phase state. COPYRIGHT: (C)2006,JPO&NCIPI |
