Thyristor Controlled Power for Single Phase Induction Motor:The power control is very significant factor specially in terms of power electronics for transmitting the power to the output load for its good performance. Different techniques or typologies are used for controlling the power by using the semiconductor devices, some of which are used the metal oxide field effect transistor(MOSFET) and some of which are used the bipolar junction transistor(BJT). Zero crossing detection circuit will be helpful for you in this electronics project. Here we would be control the single-phase motor power by connecting the thyristor at the input side of single phase motor. The power would be controlled by changing the firing angle of thyristor. This power control topology or technique has high performance and efficiency as compared to the other power control techniques. In this technique, the voltage would be detecting at every precise moment of time and then the thyristor would be triggered at any voltage. By doing this the power can be controlled easily. Here we would be made this thyristor controlled power system with the help of single phase transformer, Bridger rectifier, voltage regulator, semiconductor switch SCR, microcontroller 18F452 which is belongs to pic family, comparatorand optocoupler or opto isolator.
Block Diagram of Thyristor Controlled Power System for Single Phase Induction Motor
Components List of Thyristor Controlled Powe for Single Phase Induction Motor
Transformer: Transformer is a static device, used for step up or step down the ac voltages and works on the principle of mutual induction. In this thyristor, controlled power system, it is used for step down the 220 v into 12 v ac.
Bridge Rectifier: The bridge rectifier consists of four diodes and is used for converting the ac into dc. In this thyristor, controlled power system, it is only used for converting the ac voltage in to dc voltages.
Blocking Diode:In this thyristor, controlled power system the diode is connected at the output of bridge rectifier for blocking the reverse current towards the bridge rectifier.
Voltage Regulator: In this thyristor, controlled power system, the voltage regulator is only used for regulating the 12 dc in 5 v dc for supplying the power to the microcontroller and other electronics components.
Zero Crossing Detector: In this thyristor, controlled power system, the zero-crossing detector is basically a comparator which compares the two inputs one input comes from input side and second is the reference input which comes from maybe variable resistor or output side. When one input is grater then the other input then the comparator output would be high.
Microcontroller pic 18F452: In this thyristor, controlled power system the pic 18F452 microcontroller have been used for controlling the firing angle of the thyristor. This controller is powered up 5 v dc and interfaced with the two optocouplers. It consists of 40 pins and these pins can configure as input or output and one input comes from comparator. It is programmed in c language with help of mikro/c software.
Optocoupler: Optocoupler is a 6 pins integrated circuit device and in this thyristor controlled power system, it used for isolation purposes and for giving the firing angle to the thyristor. The thyristor is make on/off based on the optocoupler firing angel signal.
Thyristor: Thyristor is a semiconductor switch and consists of three terminals anode, cathode and gate. When the positive signal is given to the gate terminal then this thyristor would be in on condition. By changing this gate signal the thyristor can be easily make on or off.
Load:This is basically, the thyristor controlled power system and any type of load can connect at output side. Here we would be check this system by connecting the resistive load means we would be connect here the lamp.
Working Principle of The Thyristor Controlled Power System for Single Phase Induction Motor
This thyristor controlled power system works on the principle of firing angle change of the thyristor. When the firing angle is changed then the output is changed. This system has two switch one for switch on this system and one for firing angle change switch. This system is powered on directly from wapda power supply and we would be check this system by checking the brightness of the output bulb. When this system is switched on and press the firing angle switch then the comparator compare the two input and gives the signal to the microcontroller. The microcontroller in which set the delay time of firing angle through the programming language and then the microcontroller gives the delayed signal to the optocoupler then the optocoupler gives the firing signal to the thyristor. Based on this firing angle the thyristor on or off and then this thyristor on or off the output load. The firing angle is changed by changing the delay time and when the delay time is change then the output power is changed. The output power is inversely proportional to the delay time means when the delay is increase then the output power decrease. Here we would be check this system by changing the firing angle. When the firing angle is change then the output power is changed and then the brightness of the lamp is also changed.
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Different Applications and Advantages of Thyristor Controlled Power System
- Thyristor controlled power system can be used for controlling the reactive power of induction motor. By controlling the reactive power of motor, we can easily change the speed of the motor.
- This system can be used for controlling the brightness of the output bulbs.
- This system can also be used for controlling the speed of dc motors.
- This system can be used in synchronous generators for changing thefield winding excitation of the generator.by controlling the field excitation, the output voltage of synchronous generator can be controlled.
- By using this system the performance and efficiency of industrial machine can be improved.