| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the following problem: in case of overmodulation, a switch is continuously kept on and this degrades current clamp (CC) characteristics and overcurrent (OC) protection results; as a result, an inverter is abnormally stopped and at the same time, the life of an IGBT unit is shortened. <P>SOLUTION: In a discontinuous protection method for clamping phase currents in an inverter, a current clamping flag and a current threshold value are initially set. The phase currents are alternately interrupted based on whether or not the phase current exceeds the current threshold value as well as the current clamp flag. Startup of overcurrent protection and shutdown of the inverter can be prevented by analyzing current by the discontinuous method under a certain condition determined based on a criterion. In this method, further, a carrier frequency modulation flag is set. When the phase current should be interrupted, the carrier frequency is increased to 8 kHz. The protection of clamping current is thereby speeded up. <P>COPYRIGHT: (C)2010,JPO&INPIT |
