DRIVING APPARATUS FOR SEWING MACHINE MOTOR

PURPOSE:To protect a discharge means from an overvoltage without using a fuse by a method wherein discharge by the discharge means is stopped if the continuation period of the discharge exceeds a predetermined period and, further, current application to the respective phase windings of a sewing machine motor by a current applying means is stopped. CONSTITUTION:A discharge means 9 which discharges electrical charge stored in a storing means if the output voltage of a DC power supply exceeds a predetermined voltage and a stopping means 13 which stops the discharge by the discharge means 9 and, further, stops current application to the respective phase windings of a sewing machine motor M by a current applying means 7 if the continuation period exceeds a predetermined period are provided. In other words, the discharge is stopped before the discharge means 9 is thermally breakdown by the extension of the discharge period. Further, as the sewing machine motor M is turned from a rotating state to a free-running state, the sewing machine motor M is temporarily stopped by loads from respective moving mechanisms of the dewing machine driven by the dewing machine motor M. With this constitution, the discharge means 9 can be protected from an over-voltage without using a fuse.