AC servos with asynchronous machines are the cheapest solution for speed-controlled drives. They are, however, not as dynamic as direct current machines or permanently excited synchronous machines. One cause for this is the electric time constant from the stator-rotor constant. Another is the dependence of the torque on the slippage, which has a dampening effect on acceleration.
Objectives
- Optimising control loops
- 2 and 4 quadrants control
- Static speed control
- Highly dynamic speed control
- Position control
-
Step response
The set-up of an AC servo with an asynchronous machine is analysed. Measurements and calculations are used to attempt to optimise the drive for its applications
- Calculating the control difference
- Analysing loads with step of reference variable
- Approaching stability limits
Highlights:
- The measurements are carried out with the CASSY converter controller .
- All measurement channels are potential-free and can therefore be used freely.
- All measurements can be carried out with or without a computer.
- In order to protect against overheating, the stator windings of the asynchronous motor are equipped with thermal detectors.
- The asynchronous motor has an educationally designed terminal board with the winding configuration printed on it.
All functions of the Converter Controller CASSY can be operated quickly and directly via the display, the rotary wheel and the buttons on the unit. All settings and measurement results can be saved on the unit and quickly called up again later or simply downloaded.
In addition, the Converter Controller CASSY is fully controllable in real time via RJ45 Ethernet, W-LAN and USB-C interfaces.
These interfaces can be used by the following software:
- CASSY Lab 2 for drives and energy systems,
- MATLAB® and LabVIEW ™
- Lab Docs Editor Advanced
Several integrated servers are available in Converter Controller CASSY for the local media connection of at least four end devices simultaneously.
For more details, see product data 7735290 or 7735291 Converter Controller CASSY.
The equipment is equally suitable for pupil and student experiments in the laboratory with low voltage (DC, AC and three-phase current) and - with a mobile trainer - for teacher demonstrations in the classroom or lecture hall. The experiments are carried out according to the manual.
The target group is made up of commercial apprentices and students of electrical machine construction. The course offers experiments at an intermediate level and also allows for the necessary insight into machine behaviour for scientific interpretation at undergraduate level. The media connection makes the experiments suitable for demonstration in the classroom or a lecture hall.
In the following configurations there are further extended experiments performed with a frequency converter and an asynchronous machine:
- E2.5.3.2 Basics of frequency converter technology
- E2.5.3.3 Drives with educational frequency converter
- E2.5.4.4 Operating behaviour of speed-variable asynchronous motors under load
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