What is the difference between a velocity mode servo amplifier and a current mode servo amplifier?
A current mode amplifier has an internal feedback loop that uses the measured electrical current going to the motor as feedback. Since motor torque is proportional to the electrical current driving the motor, a current mode amplifier is also known as a torque mode amplifier. Analog current mode (torque mode) amplifiers typically require that the user manually “tune” or calibrate the current loop of the amplifier using trim potentiometers, while following a set procedure provided by the manufacturer. A velocity mode amplifier has both an internal current loop and a velocity loop. Typically, a tachometer is used to provide velocity feedback to a velocity mode amplifier. In this case, the ±10V analog command output signal from the motion controller is configured as a velocity command signal, and the servo controller uses a Feed Forward term (also known as Velocity Gain) in it’s PID filter to calibrate the velocity command to the amplifier. For servo systems that use velocity mode amplifie
