Clear up the concept first
An asynchronous servo motor can look like an ordinary induction motor with an encoder, but its design goal differs. A standard three-phase asynchronous motor aims to 'run reliably, cheaply and durably'; a servo motor aims to 'follow commands, accelerate fast and position accurately'.
| Item | Standard induction motor | Asynchronous servo motor |
|---|---|---|
| Dynamic response | Average | Fast, good tracking |
| Speed range | Narrow | Wide, low to high speed |
| Positioning accuracy | Low | High, needs encoder/drive |
| Control | DOL / soft start / VFD | Closed-loop servo drive |
| Cost | Low | Higher (with drive) |
When to use an asynchronous servo
When the machine needs frequent start/stop, fast acceleration/deceleration, precise following, or wide speed range, the servo pays off. Typical uses: automation stations, robots / linked lines, high-precision winding, positioning conveyors. For a fan or pump that just 'needs to spin', a standard (VFD) motor is more economical.
Asynchronous servo vs permanent-magnet servo
Servos also split into asynchronous and permanent-magnet synchronous. The asynchronous servo (e.g. YPT, YJP) favours field-weakening high speed, large power and high temperature; the PM servo (TBVP) is more efficient and compact for medium/low speed precision. Choose by speed range and efficiency needs.
Parameters to provide
- Power & torque: from load torque and speed.
- Speed range: min/max speed, to decide if field weakening is needed.
- Control: which drive, closed-loop or not.
- Duty: continuous or frequent start/stop (e.g. S5).
- Mounting & shaft: frame, flange/foot mounting.
Wangpai servo range
Wangpai offers YPT asynchronous servo (5.5~1400 kW) and YJP asynchronous servo (7.5~1250 kW), plus VFD motors, with custom voltage and frame.
Servo motor FAQs
Does a servo motor need a drive? Yes. The value of a servo is closed-loop control, so it needs a servo drive.
Can an asynchronous servo run on a normal VFD? For low-speed duty it can, but for true servo positioning you need a servo drive with encoder.
How do I know if a machine needs a servo? If it needs frequent start/stop, precise following or wide speed range, and is sensitive to response, consider a servo.
Can Wangpai customise to my machine? Yes - send the load, speed and control method and we will match the frame and solution.