Current Mode Control for Servo Drives

Current Mode Control allows for precise torque control, making it suitable for applications that require high accuracy and responsiveness, such as robotics, CNC (Computer Numerical Control) machines, automation systems and more.

In Current Mode, the input command controls the output current. Only the current loop is active in this mode, and the velocity loop and position loop are either disabled, non-existent, or closed outside of the servo drive.

Because of this, current mode is usually considered the most basic operating mode of motion control.

Control block diagram for servo control with broken out section highlighting details of the current control loop.

Aside: What does "closed outside of the servo drive” mean? It means the servo drive is in current mode, but an external motion controller is responsible for the velocity and position. The motion controller monitors the movement and sends the correct commands to the servo drive to achieve the desired motion.

Current Mode is also called Torque or Force Mode since the output torque/force is proportional to the motor current. This means the drive will not compensate if an outside torque is applied to the motor shaft in the opposite direction; it will simply maintain the same current output that it is commanded.

Segment of electrical iagram showing 2 lines between Source and Destination, both branching off to Vcc


  • By using current mode, you can more accurately control the motor’s torque output. This allows for finer adjustments and smoother movements.
  • Allows for quicker response times. This is particularly beneficial in dynamic systems where the motor needs to react rapidly to changing conditions or commands.
  • In some applications, it is essential to limit the current to prevent damage to the motor or other system components. Current mode makes it easier to implement such limiting measures.
  • Provides direct control of the motor’s current consumption, enabling better power management capabilities.
  • Because current and torque are directly proportional, calculations become remarkably simple.
  • The most simplified form of motor control
  • Allows other motion control devices to close the velocity and position loops while the servo drive closes the current loop.


ADVANCED Motion Controls' Capabilities

  • Current Mode is a selectable option on almost all offered servo drives
  • Certain FlexPro® and DigiFlex® Performance drives can operate in Profile or Cyclic Synchronous Current Mode

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