The working modes of servo driver are: open loop mode, voltage mode, current mode (torque mode), IR compensation mode, Hall speed mode, encoder speed mode, tachometer mode, and analog position loop mode (ANP mode). (not all of the above modes exist in all models of drives)
The input command voltage controls the output load rate of the driver. This mode is used for brushless motor driver, and the voltage mode is the same as that of brush motor driver.
The input command voltage controls the output voltage of the driver. This mode is used for the brushless motor driver and is the same as the open-loop mode of the brushless motor driver.
The input command voltage controls the output current (torque) of the driver. The driver adjusts the load rate to maintain the command current value. If the servo driver can work in the speed or position loop, it usually contains this mode.
Input command to control motor speed. IR compensation mode can be used to control the speed of motor without speed feedback device. The driver will adjust the load rate to compensate for the change of output current. When the command response is linear, the accuracy of this mode is less than that of the closed-loop speed mode in the case of torque disturbance.
Input command voltage to control motor speed. This mode uses the frequency of Hall sensor on the motor to form a speed closed loop. Due to the low resolution of Hall sensor, this mode is not generally used for low-speed motion applications.
Input command voltage to control motor speed. This mode uses the frequency of encoder pulse on servo motor to form speed closed loop. Due to the high resolution of the encoder, this mode can be used for smooth motion control at various speeds.
Input command voltage to control motor speed. In this mode, the speed closed loop is formed by simulating the tachometer on the motor. Because the voltage of DC tachometer is analog continuous, this mode is suitable for high precision speed control. Of course, it is also vulnerable to interference at low speeds.
Input command voltage to control the rotation position of motor. This is actually a speed mode (such as adjustable potentiometer, transformer, etc.) that provides position feedback in the analog device. In this mode, the motor speed is proportional to the position error. It has faster response and smaller steady-state error.