Wesley BC-620-4CA - Manual (Page 127)

Curtis 1234/36/38 Manual, os 11
Fig. A-2 Power section
topology.
Heavy busbars connect the IMS modules to the external motor connec-
tion studs. A bank of power capacitors keeps DC bus levels stable during high
frequency MOSFET switching and also reduces EMI on the external B+ and
B- cables.
Motor currents and motor speed and direction are the primary feedback
signals used in the motor control algorithms. Accurate Hall sensors detect the
motor currents; they do this by sensing the flux created by the motor currents
on the U and V motor output busbars where they pass through the capacitor
board on their way to the external motor connections. Motor speed and direc-
tion are simultaneously sensed by a quadrature-type speed encoder mounted
on the motor shaft.
APPENDIX A: THEORY OF OPERATION
A-3