User:Aholyokeb/Torque amplifer

A torque amplifier is the device that does the driving of the motor. It controls the current flowing through the motor. There is a control loop that does the controlling function in the amplifier. The amplifier voltage input is a current command signal. The amplifier closes the loop between the command and the actual current through the motor. Another control loop outside the current or torque loop is the speed or velocity loop. This control loop controls the speed of the motor by using a tachometer or encoder for the feedback. The outer control loop is the position loop. This loop gets the actual position feedback signal from a positioning potentiometer or an LVDT. As a position needs changing, the position loop commands the velocity loop to speed up the motor. The velocity loop commands the torque loop to drive more current into the motor to make it speed up.

A torque control amplifier controls the torque of the motor by controlling the current going through the winding of the motor. A voltage is applied to the command input, and the amplifier control loop sets up a controlled current through the motor. The controller will output exactly what is commanded of it. However, there are limits. The main limit is the acceptable command range of the device. If the device is designed and rated for a 10 amp limit, then asking 15 amps of the device will not work. The circuitry is designed to have a maximum control range. If that is exceeded, the loop can no longer maintain control. The current may go higher, but it won’t be under control. MSK’s torque controllers have current limits built in for that reason. Otherwise, the current could continue to rise to an unacceptable level, destroying the output stage.