A method for controlling a motor (11) driving a pump (10) using
a
microcomputer (14) includes repeatedly sampling a parameter representative
of motor torque over one cycle of operation of the pump (10), determining
at least one point of maximum motor torque during said one cycle of operation of
the pump (FIG. 4); applying speed commands to the motor (11) from
a table of stored speed values in memory (19), said values being selected
to provide relatively greater speed commands at points of lower motor torque and
relatively lesser speed commands at points of higher pump pressure corresponding
to higher motor torque, while maintaining at least a base speed command to prevent
stalling; and synchronizing the first value in the table of stored values to the
point of maximum motor torque.