Electric motor control systems

摘要

In an electric motor control system motor M is controlled from an impedance bridge circuit. An adjustable control impedance TH1 is set by manual or automatic control and an adjustable feedback impedance FB1 is adjusted mechanically by rotation of the motor M. The control system has means R1, TR.1 for monitoring a stall-indicating characteristic of the motor and means Ic.2d, TR.2 to cut off the power supply to the motor when the characteristic indicates that the motor is close to or has reached a stall condition. It also has comparator means Ic.2a for comparing the potential inputs such that when the power supply to the motor has been cut-off it can only be restored in response to the output of the comparator if there is imbalance between the potential inputs in the opposite sense to that existing when the power supply was cut-off.