 Operating Mode of the AB Servo Drive

The CNC servo driver can choose the following operating modes: open loop mode, voltage mode, current mode (torque mode), IR compensation mode, Hall speed mode, encoder speed mode, speed detector mode, analog position loop mode (ANP mode). (Not all of the above modes are available on all drives)

1. Open loop mode of ab servo drive

The input command controls the output load rate of the ab servo drive. This mode is used for brushless motor drivers and it is the same voltage mode as the brush motor driver.

2. Voltage mode of ab servo drive

The input command controls the output voltage of the ab servo drive. This mode is used for brushless motor drives, and it is the same as the open loop mode for brushless motor drives.

3. Current mode of servo driver (torque mode)

The input command controls the output current (torque) of the ab servo drive. The servo driver adjusts the load rate to maintain the command current value. If the servo driver can adjust the speed or position, this mode is generally included.

4. IR compensation mode of ab servo drive

Input command to control motor speed. IR compensation mode can be used to control the speed of motor without speed feedback device. The ab servo drive adjusts the load rate to compensate for variations in the output current. When the command response is linear, the accuracy of this mode is not as good as that of the closed-loop speed mode under torque disturbance.

5. Hall speed mode of ab servo drive

Input command to control motor speed. This mode uses the frequency of the Hall sensor on the motor to form a speed loop. Due to the low resolution of the Hall sensor, this mode is generally not used in low-speed motion applications.

6. Encoder speed mode of ab servo drive

Input command to control motor speed. This mode uses the frequency of the encoder pulse on the servo motor to form a speed loop. Due to the high resolution of the encoder, this mode can be used for smooth motion control at various speeds.

7. Speed detector mode of ab servo drive

Input command to control motor speed. In this mode, a speed closed loop is formed by using an analog velocimeter on a motor. Because the voltage of DC tachometer is analog continuous, this mode is suitable for high precision speed control. Of course, it is also susceptible to interference at low speeds.

8. Analog position loop mode (ANP mode) of ab servo drive

The input command to control the rotation position of the motor. This is actually a variable speed mode that provides position feedback in analog devices (like adjustable potentiometers, transformers, etc.). In this mode, motor speed is proportional to position error. It also has faster response and smaller steady-state error.