Flyback Circuit
Pump Control Circuit
D4P is a flyback diode for the hydraulic pump motor circuit. This circuit uses the current created by the collapsing magnetic field of the field windings in the pump motor to keep current flowing when transistors T1P, T2P and T3P are OFF. When T1P, T2P and T3P are OFF, all current from the field goes through PD2, D4P, PA1 and the pump motor armature (ARM) back to the field. When T1P, T2P and T3P are pulsing, the flyback
MicroCommand Control System
circuit causes the average pump motor current to be greater than the average battery current through T1P, T2P, and T3P. The steering system is self-compensating for battery voltage. The logics will increase the “on-time” of T1P, T2P and T3P when the battery voltage changes.
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Systems Operation
