DC servo with industrial DC machine

E2.6.2.1 DC servo with industrial direct current machine

DC servos have a wide range of applications, highly dynamic control was only possible with them for a long time. In many applications, they have been replaced by permanently excited synchronous machines. This is because of the higher maintenance cost and lower efficiency of direct current machines. A modern, angle-oriented speed control requires an incremental recording of the rotation angle.

Objectives

• Optimising control loops
• 2 and 4 quadrants control
• Static speed control
• Dynamic speed control
• Highly dynamic speed control
• Position control

• Step response

The learner analyses the set-up and function of a DC servo drive on the DC drive. 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 care 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 direct current machine are equipped with thermal detectors.
• The direct current parallel machine has a didactic 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 drive technology experiments:

• E2.5.2.2 Four-quadrant operation of a direct current machine with an IGBT-H bridge circuit
• E2.5.4.5 Operating behaviour of speed-variable direct current machines under load

Topics

• Coupling of motor and commutation encoder
• Stationary behaviour
• Measurement of the motor current
• Variation of the modulation frequency
• Dynamic behaviour
• Structure of the control
• Investigation of the angular acceleration depending on the maximum limit current
• Position control with and without subordinate current and speed controllers
• Investigation of positioning time and overshooting depending on speed and current limits and ramp time