The experiments are carried out using DC machines of industrial manufacture. The power is supplied to the machine under test via a thyristor speed controller.
Objectives
- Protective measures and electrical safety
- Setting up variable speed DC drives and putting them into operation
- Assessment of control response
- Use of Power Analyser CASSY Plus
Traditionally, thyristors are used for variable-speed drives with high drive power. By adjusting the armature voltage, the speed can be changed and by reversing the polarity of the rotor voltage, the direction of rotation can be changed. The converter-fed DC drive is a widely used, controlled electric drive for high power. The reason for this is the robust, well-engineered and inexpensive speed control devices and the high control dynamics of the entire system.
Highlights:
- The measurements are carried out with the Power Analyser Plus.
- 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 DC machines are equipped with temperature detectors
- The test machines are equipped with an educationally designed terminal board with the winding configuration printed on it.
All functions of the Power Analyser 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 Power Analyser 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
The following integrated servers are available in the Power Analyser CASSY for the local media connection of at least four end devices simultaneously.
For more details, see product data 727110 or 727111 Power Analyser CASSY.
The individual equipment is equally suitable for student experiments in the laboratory with low voltage 90 / 156 V DC) and - with a mobile trainer - for teacher demonstration in the classroom. 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 experiments with controlled rectifiers and a DC machine:
- E2.4.2.1 Uncontrolled / controlled rectifier circuits
- E2.5.2.2 Four-quadrant drive of a DC machine with an IGBT H-bridge circuit
- E2.5.4.5 Operating behaviour of speed variable DC machines under load
- E2.6.2.1 DC servo with industrial DC machine
Topics
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Automatic control of multi-quadrant drive
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Introduction to the requirements
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Analysis of controlled systems
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Analysis of actuating static converters
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Optimisation of the current control loop
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Recording of armature circuit constants
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Adaptation of current controller
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Adjustment of current limiting
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Optimisation of speed control loop
- Putting thyristor speed control in the first quadrant into operation
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Setting of DC chopper and inverter stability limits
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Recording of static converter control characteristic
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Determination of short-circuit time constants of armature windings
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Recording of the transient function of the controlled variable, armature current
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Recording of the transient function of the controlled variable, armature current, with and without adaptive controller
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Switchover of static converter
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Setting current limiting
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Determination of the integral action time for the drive
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Determination of the transfer function of the controlled variable (speed)
- Recording a switching diagram
