motor armature winding. Any of the SCR pairs (SCR1, SCR2), (SCR2, SCR3), (SCR3, SCR4) and (SCR1, SCR4) could also be diodes. FIG. 16 shows a 3-phase full-wave D.C. motor control system for 2-quadrant operation. As shown therein, the three power lines L1, L2, L3 of a...