Can Induction Motor Be Controlled by a Servo Drive? Here’s How — Including Setup on Siemens SINAMICS S120 and Allen bradley

Can an Induction Motor Be Controlled by a Servo Drive? Here’s How — Including Setup on Siemens SINAMICS S120

Yes — it’s absolutely possible!

While Induction Motors (also known as asynchronous motors) are typically controlled by standard VFDs (Variable Frequency Drives), they can also be controlled using servo drives in certain applications. Brands like Allen-Bradley (Kinetix 5300/5700) and Siemens (SINAMICS S120) support this functionality — especially when precise motion control is required but not critical.

In fact, if a servo motor fails and no spare is available, using an induction motor as a temporary or even long-term replacement is a practical solution worth considering.

When Should You Use an Induction Motor Instead of a Servo?

✅ When precision and fast dynamic response are not critical, such as in conveyor systems
✅ When cost matters – Induction motors are significantly cheaper than servo motors, especially at higher power ratings
✅ For high inertia and high-power applications like material handling, where the heavier rotor of the induction motor is beneficial

Key Differences Between Induction and Servo Motors

🔹 Precision & Response Time: Servo motors provide higher accuracy and faster response.
🔹 Size: Induction motors are generally bulkier than servo motors with the same kW rating.
🔹 Energy Efficiency: Servo motors (especially permanent magnet types) are more efficient.
🔹 Inertia: Induction motors have higher rotor inertia — important for acceleration/deceleration times.
🔹 Drive Setup: Servo drives require careful configuration when used with induction motors (scaling, feedback, polarity, etc.)

Setting Up an Induction Motor on a Siemens SINAMICS S120 Servo Drive

Here’s a step-by-step overview for using SINAMICS S120 with an AC Induction Motor for motion applications:

🛠 Hardware Required:

  1. AC Induction Motor (with nameplate data available)

  2. Siemens SINAMICS S120 Servo Drive system

  3. CU320-2 Control Unit (or equivalent)

  4. Motor feedback device (incremental encoder recommended)

  5. Siemens PLC (e.g., S7-1500 with integrated motion control)

  6. Drive Software: STARTER or TIA Portal with SINAMICS Startdrive

  7. Optional: PROFIBUS/PROFINET/Ethernet for communication

⚙️ Configuration Steps:

1. Wire the Motor and Feedback

  • Connect the motor leads (U, V, W) to the motor module

  • Connect the encoder to the encoder interface

  • Ensure proper grounding and shielding for noise immunity

2. Startup via STARTER or TIA Portal

  • Open your project and go to the S120 drive system

  • Run the commissioning wizard

3. Motor Data Entry

  • Select Rotary Induction Motor

  • Enter motor nameplate data: rated voltage, frequency, current, power, speed, etc.

  • Input encoder data (type, resolution, differential signal)

4. Enable Position Control Mode

  • Under control structure, choose Torque → Speed → Position Control Loop

  • Activate Position Control as primary mode

5. Configure Axis

  • Create a new axis and link it with the drive object

  • Enable positioning parameters (e.g., positioning mode, limits, scaling)

6. Feedback Testing

  • Rotate motor manually and check position feedback

  • If direction is reversed, adjust encoder wiring or modify polarity settings

7. Fault Handling

  • Clear faults via “Acknowledge Fault” in STARTER

  • Ensure all digital inputs (Enable, Start, etc.) are properly configured

8. Motion Testing

  • Use test mode to simulate basic moves

  • Program simple motion instructions in your PLC or in Drive Control Chart (DCC)

✅ Notes:

  • Always ensure the drive’s current rating matches or exceeds motor requirements

  • Use braking resistors if needed for fast deceleration

  • Don’t forget to set time synchronization between drive and PLC for coordinated motion

  • Consider inertia load when setting acceleration and deceleration ramps

 

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Summary

Controlling an induction motor using a servo drive — like the Siemens SINAMICS S120 — is not only possible, but can be extremely useful in many industrial settings where precision is moderate and cost is a concern.

This setup allows for flexibility and can keep your system running when a servo motor isn’t available or necessary.

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