| 摘要 |
Current sense voltages (VCSl~VCSn), which are the detected values of n (>=2) IGBTs connected in parallel, are converted into digital form, and thereafter, are subjected to an operation processing. After the current sense voltages (VCSl~VCSn) are converted into collector currents (Il~In) by use of constants (Gl~Gn and VOFFSETl~VOFFSETn)(step 103), current deviations (DELTAIl~DELTAIn) respectively defined as differences of the collector currents (Il~In) from the average (IAVG) thereof are calculated (step 104, 105). Drive control voltages (VDl~VDn) are renewed by changes (DELTAVDl~DELTAVDn) which are respectively obtained by multiplying the current deviations (DELTAIl~DELTAIn) by factors (Kij)(step 106, 107). The drive control voltage (VDl~VDn) are converted into analogue form, and thereafter, supplied to n IGBTs as their gate voltages (VGE). The constants (Gl~Gn, VOFFSETl~VOFFSETn, and Kij) are prepared individually for respective n switching elements. As a result, current imbalance of plural switching elements connected in parallel is eliminated in high precision.
|
