- a body where are mounted electric equipment, electronic cards, front panel;
- electromechanical unit with a DC motor of separate excitation, a squirrel-cage motor, incremental encoder with determining the rotation direction.
The body accommodates:
- Frequency converter, intended for the formation of a three-phase AC network of adjustable frequency and supply voltage of an asynchronous electric motor. The converter is based on Fujitsu microcontroller and a Mitsubishi power intelligent module.
Controller is for calculating the input and output signals of the converter, data exchanging with PC, displaying the measured values at the stand front panel.
The power module includes the power circuits of a bridge rectifier, a three-phase bridge inverter on IGBT transistors, as well as driver and protection circuits.
- Two pulse-width converters are dedicated for feeding the armature circuit, excitation winding of dc motor or active-inductive load.
Pulse-width converters are realized base on elements of frequency converter. Two its arms are used for getting the reverse PWC, and the rest arm is used as non-reverse PWC for feeding the PWC excitation winding.
Reversible PWC can operate in symmetrical (alternate diagonal connection) or asymmetric (diagonal connection of one pair of transistors) mode.
- Measuring module, constructed on digital instruments.
- Relay-contactor unit allows to perform:
- rheostatic start of DC motor;
- dynamic braking of DC motor;
- reverse-current braking of DC motor;
- dynamic braking of asynchronous motor and reverse braking.
- Analog regulators are dedicated for studying the closed loop systems:
- single-loop dc motor current stabilization;
- single-loop speed stabilization of DC motor with speed controller;
- dual-circuit speed stabilization of a DC motor with speed and current controllers.
- Resistors in armature circuit (three stages);
- Dynamic braking resistors of DC motor;
- Actuators and relays of relay subsystem;
- Overvoltage energy reset resistors on smart modules.
The panel has switching sockets, indicators of digital devices, switching equipment, as well as controls that allow you to change the parameters of elements during laboratory work.
Control elements at the stand front panel:
- setting potentiometer for controlling a reversible pulse-width converter, toggle switch of the converter operating mode (independent / symmetrical);
- setting potentiometer of a pulse-width converter for powering the field winding of a DC motor;
- setting potentiometers of the frequency converter, allowing smoothly change the output frequency reference, output voltage, dynamic braking current of an asynchronous electric motor;
- setting potentiometers of the closed-loop system reference signal, adjustment of the current and speed feedback coefficients;
- stopwatch and three-stage start controls;
- relay subsystem controls.
To carry out laboratory work, it is necessary to connect the circuit of the object under study using unified jumpers that allow to see the circuit visually.
The training system is supplied with:
- a set of methodical and technical documentation for teaching staff;
- a software.