| 摘要 |
PROBLEM TO BE SOLVED: To provide a first level discriminating means of simple and low cost which discriminates the relations of the sizes, of respective phase power supply voltages, and to enable continuous operation by backing up instantaneously, even if abnormalities occur at a second level discriminating means which is added, as required. SOLUTION: The control unit of an AC-AC direct conversion device such as a matrix converter outputs a polyphase AC voltage, having arbitrary level and frequency by switching AC switches S1-S9 connected to a polyphase AC power source. It comprises a phase detecting means 2 for detecting the phase of a power supply voltage, a first level discriminating means 3 for discriminating relationship, difference in level, of respective phase power supply voltages from the detected phase, and a commutation pattern generating means 4 for deciding the switching pattern of the AC switch according to the level discrimination signal. COPYRIGHT: (C)2005,JPO&NCIPI
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