AN-NAJAH NATIONAL UNIVERITY DEPARTMENT OF ELECTRICAL ENGINEERING THREE PHASE THYRISTOR BRIDGE CONTROLLED BY MICROPROCESSOR PREPARED BY: NABEEL MASSRI MOUSA NASIEF INSTRUCTOR : PROF. MARWAN MAHMOUD 2008/2009 Next

Back SIX PULSE LEC PRIDGE RECTIFIER:

o Six pulse bridge is the most common one. o It can be use to control the speed of DC motors. o It’s output power could be more than 120KW. Back Advantages

o Widely used in three phase dual convertors systems (UPS). Back

o The thyristors are to be triggered every  / 3. o Two quadratic operations is possible. o Could be used in continuous and discontinuous mode. Back Properties

building three phase bridge and make investigations about Its input and output characteristics Back

 555 Timer Astable And Monostable Multivibrator f = 1.44/(C1(R1+2R2)), wherein f is in Hz if R1 and R2 are in mega ohms and C1 is in microfarads.

 Unijunction Transistor Relaxation Oscillator

 Pulse transformers

o We used the idea of zero cross detector o We used PIC 16F877 to do the triggering program. Back

Input voltage Output voltage

START Thyristor Read the value of the Input voltage If value =0v Delay =(firing angel) Output the triggering pulse BackY N

Triggering at 0 Triggering at 45 Triggering at 90 Triggering at 135

We chose the thyristor to work on which is TIC 116. o 8 A Continuous On-State Current o 400 V to 800 V Off-State Voltage. o Max IGT of 20 mA. Back

The wave forms for continuous operations. Back

o immediately from the PIC

o Using Triac Photo Coupler (MOC 3020)

o Using Transistor Photo Coupler (4N25)

o The complete circuit

Output voltage form at α= 90۫˚Output voltage form at α= 60۫˚ Output voltage form at α= 30۫˚Output voltage form at α= 0۫˚

Input current form at α= 90۫˚Input current form at α= 60۫˚ Input current form at α= 30۫˚Input current form at α= 0۫˚

Output voltage form at α= 90۫˚Output voltage form at α= 60۫˚ Output voltage form at α= 30۫˚Output voltage form at α= 0۫˚

The load angel could be measured by the following equation:  Ф= tan -1 (wl/R)  For example: If R= 16Ω and L= 50mh then the load angle can be calculated as a following: Ф= 44.5 Note :RL load is tested under discontinuous operation because it dose not affect the shape of output voltage for the continuous operation.

Output voltage form at Ф= 67۫˚Output voltage form at Ф= 55۫˚ Output voltage form at Ф= 36۫˚ ۫˚ Output voltage form at Ф= 25۫˚

Input current form at Ф= 67۫˚Input current form at Ф= 55۫˚ Input current form at Ф= 36۫˚ ۫˚ Input current form at Ф= 25۫˚

o The bridge could be used to control the speed of DC motor Connected to its output terminal by changing the output voltage Which depend on the firing angle

Output voltage form at α= 90۫˚Output voltage form at α= 60۫˚ Output voltage form at α= 30۫˚Output voltage form at α= 0۫˚

Input current form at α= 90۫˚Input current form at α= 60۫˚ Input current form at α= 30۫˚Input current form at α= 0۫˚

 The input current contains high frequencies  These frequencies has badly effects on the electrical network  These frequencies has badly effects on the communication devices  Removing these harmonics is capable by using filters  These harmonics are given by:  Hvd=6,12,18,24,30,………  Fde=300,600,900,1200,1500…………

 Using LC resonance circuit  Practically the values of L and C are not available in our market because we need to use non polar capacitor with high capacity and high voltages, also we face problems in finding the suitable value of inductors.

 Using low pass filter circuit  Using polar capacitors for large capacity with high voltage rating.  The input current form improved.

Input current form at fc=318Input current form at fc=500 Input current form at fc= 636Input current form at fc=1590۫

Applications:  1-Power electronic lab unit  2- DC motor speed controller  3-Battery charger  4- Part of uninterrupted power system(UPS). Discussion and conclusion Discussion and conclusion

benefits:  Improve our skills in designing electronic circuits and interfaces by using the simple electronic components (resistors, capacitors, transformers and diods), and more complicated components like photo couplers.  Learn how to use the measurement devices and how to take accurate measurement by using multimeter and oscilloscope.  Have a basic idea about how to use microprocessor (PIC), building its basic and program it successfully.  Have a good acknowledgment about the basic power electronics component (thyristor).  Understanding the concepts of power electronic like triggering (firing angel), thyristor turn

Future suggestions :  Varying the firing angle of the thyristor of this circuit by using potentiometer (this need high level of calibration for the thyristor firing angle with the PIC analog to digital by programming ).  Using this circuit in industrial application but for huge applications the thyristor should be changed to be more suitable and stand with high currents.  Use this circuit to build a complete uninterrupted power system ( UPS).