| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a motor driving circuit which detects a current, using the ON resistance of a switching element F1 that is used for an inverter circuit 7 as a substitute for a current sensor. <P>SOLUTION: A microcomputer detects the forward voltage V1 when a reflux current ID1 flows to a diode D1 and the voltage drop V2 by the ON resistance when a drive current flows to a switching element F1. Then, it estimates the junction temperature of the switching element F1 from V1, and corrects the temperature properties of the ON resistance, based on the estimated temperature. Subsequently, it computes the drive current, based on the ON resistance after correction and V2 taken in before. Hereby, it can eliminate the effect of the junction temperature of the switching element F1, so it can accurately detect the drive current of the inverter circuit 7. Moreover, since it detects the drive current, using the ON resistance that the switching element F1 has, it can abolish a conventional current sensor (for example, a shunt resistor). <P>COPYRIGHT: (C)2006,JPO&NCIPI |
