Structurally, the training system consists of two parts:
- the case in which a part of the electrical equipment, electronic boards, front panel and countertop of the integrated desktop are installed;
- two machine units, each of which includes one asynchronous electric motor with a phase rotor, one asynchronous electric motor with a squirrel-cage rotor, as well as an optical speed sensor.
The stand can be equipped with an electric machine based on electric motors of small (90 W) or large (0.55 kW) power.
The following equipment is located inside:
- Two frequency converters designed to form a three-phase AC network of adjustable frequency and supply voltage of running short-circuited asynchronous electric motors. The converters are based on the MB90F562 microcontroller (Fujitsu) and the PS11035 (Mitsubishi) power intelligent module.
The controller serves for calculating input (voltage and frequency settings) and output (power, voltage) signals, organizing data exchange with a PC, and outputting measured values ??to the front panel of the stand.
- Power circuits of a three-phase bridge rectifier, three-phase bridge inverter on IGBT transistors, as well as driver and protection circuits (from short circuit currents, insufficient driver supply voltage, incorrect supply of control signals).
- A pulse-width converter designed to power the rotor circuits of a three-phase asynchronous motor with a phase rotor in generator mode. A pulse-width converter is implemented on the power element base of the frequency converter. Its two shoulders are used as non-reversible ICPs for rotors of a three-phase induction motor.
The control system is based on the AT Mega163 (Atmel) microcontroller and implements calculations of input (current setting) and output (rotor current, engine speed) signals, organizes data exchange with a PC, displays measured values on the front panel of the stand.
- The measurement module is built on the basis of a digital measuring system built into the stand and connected to a personal computer via the USB bus. Laboratory work is possible both in manual mode and in dialogue mode with a personal computer.
- Relay-contactor control, which allows to:
– connect generators for parallel operation with a network of 3 ~ 50 Hz 220/127 V;
– connect the load, choose its type (active, active-inductive, active-capacitive) and its value.
- Overvoltage reset resistors on smart modules.
- Incandescent lamps for synchronizing a three-phase generator with the network.
The frequency converter and the pulse-width converter are included in the joint operation of the internal network (recovery mode) to reduce the power consumption from the network.
The power module includes:
- power starters of the relay subsystem;
- load resistors, capacitors and inductors in a three-phase circuit (three stages).
On the front panel of the stand are electrical circuits of objects of study. All schemes are divided into groups in accordance with the theme of ongoing laboratory work. The panel contains switching sockets, indicators of digital devices, switching equipment, as well as controls that allow you to change the parameters of the elements during laboratory work.
The controls on the front panel of the stand:
- master potentiometers for controlling non-reversible pulse-width converters of power supply of rotors of asynchronous electric motors with a phase rotor in the mode of synchronous machines;
- setting potentiometers of frequency converters, allowing to smoothly change the task of the output frequency (0÷163 Hz), output voltage (0÷220 V);
controls for the relay subsystem.
To conduct laboratory work, it is necessary to assemble a diagram of the object of study using standardized jumpers, which allow you to present the diagram in a visual form.
Laboratory work is possible both in manual mode and in dialogue mode with a personal computer.
The training system is supplied with:
- student testing software for admission to laboratory work. In the testing process, both theoretical knowledge and knowledge of the contents of the laboratory work performed are checked. As a result of testing, the student receives an assessment of knowledge;
- a set of methodological and technical documentation intended for the teaching staff.