1. rectifiers

3. Introductions of rectifiers: IN PARTICLE ACCELERATORS, ELECTRONS OR OTHER CHARGED PARTICLES ARE FORCED TO MOVE ALONG ORBITS OR TRAJECTORIES BY MEANS OF MAGNETIC FIELDS. THE INTENSITY OF THE MAGNETIC FIELDS NEEDED TO OBTAIN THE DESIRED EFFECTS IS RELATED TO THE ENERGY OF THE PARTICLES. ELECTROMAGNETS, CONVENTIONAL HOT ONES OR SUPERCONDUCTING ONES, ARE NORMALLY USED. THE EXCITATION CURRENT IN THE MAGNETS CAN RANGE FROM SOME AMPERES FOR SMALL ORBIT CORRECTION COILS TO SOME HUNDREDS OR THOUSANDS OF AMPERES (SEE, FOR EXAMPLE, REFS. [1] AND [2]). THE POWER CONVERTERS NEEDED TO COVER SUCH A WIDE CURRENT RANGE HAVE WIDELY DIFFERING STRUCTURES AND CHARACTERISTICS AND, FOR THE SAME POWER REQUIREMENT, SEVERAL SOLUTIONS ARE OFTEN POSSIBLE. IN THIS PAPER I SHOW THE TOPOLOGIES AND THE CHARACTERISTICS OF A PARTICULAR CLASS OF RECTIFIERS—THE LINE COMMUTATED ONES—THAT WAS AND STILL IS WIDELY USED IN PARTICLE ACCELERATOR FACILITIES. EVEN TODAY, IN THE ‘PWM ERA’, LINE COMMUTATED RECTIFIERS ARE OPERATING. MOREOVER, SWITCH MODE POWER SUPPLIES (SMPS) VERY OFTEN INCLUDE IN THEIR STRUCTURE ‘CONVENTIONAL’ RECTIFIERS AS INPUT OR OUTPUT STAGES OR BOTH. SINCE THE CURRENTS IN THE MAGNETS HAVE EITHER TO BE VARIED ACCORDING TO THE ENERGY (OR THE REQUIRED CHANGES IN THE ORBIT) OF THE PARTICLES OR AT LEAST HAVE TO BE RAMPED FROM THE TURN ON VALUES TO THEIR FINAL VALUES (THIS IS QUITE IMPORTANT IF THE TIME CONSTANT OF THE LOAD — A MAGNET STRING — IS HIGH), THE RECTIFIERS USE THYRISTOR-BASED STRUCTURES OR MIXED ONES (DIODES AND THYRISTORS OR DIODES/THYRISTORS AND TRANSISTORS).

4. Definition of rectifiers A RECTIFIER IS AN ELECTRICAL DEVICE COMPOSED OF ONE OR MORE DIODES THAT CONVERTS ALTERNATING CURRENT (AC) TO DIRECT CURRENT (DC). A DIODE IS LIKE A ONE-WAY VALVE THAT ALLOWS AN ELECTRICAL CURRENT TO FLOW IN ONLY ONE DIRECTION. THIS PROCESS IS CALLED RECTIFICATION.

5. Block diagram of power supply

6. rectifier HALF WAVE RECTIFIER FULL WAVE RECTIFIER CENTRE TAPPED RECTIFIER. BRIDGE RECTIFIER.

7. Halfwave rectifier AS THE NAME SUGGESTS, THE HALF WAVE RECTIFIER IS A TYPE OF RECTIFIER WHICH CONVERTS HALF OF THE AC INPUT SIGNAL (POSITIVE HALF CYCLE) INTO PULSATING DC OUTPUT SIGNAL AND THE REMAINING HALF SIGNAL (NEGATIVE HALF CYCLE) IS BLOCKED OR LOST. IN HALF WAVE RECTIFIER CIRCUIT, WE USE ONLY A SINGLE DIODE.

8. Operation of half wave rectifier OPERATION OF HALF-WAVE RECTIFIER. PN JUNCTION DIODE CONDUCTS ONLY DURING THE FORWARD BIAS CONDITION.... ALTERNATING CURRENT IS THE INPUT OF THE HALF WAVE RECTIFIER. A STEP DOWN TRANSFORMER TAKES INPUT VOLTAGE AND THE RESULTING OUTPUT OF THE TRANSFORMER IS GIVEN TO THE LOAD RESISTOR AND TO THE DIODE.

10. Wave forms half wave rectifier

11. Average dc load current(I DC )

12. AVERAGE DC VOLTAGE(E DC )

13. I RMS AND E RMS

14. DC POWER DELIVERED TO THE LOAD

16. Rectifier efficiency

17. ADVANTAGES OF HALF WAVE RECTIFIER 1)IT IS A SIMPLE CIRCUIT. 2)IT HAS LOW COST. 3)WE CAN EASILY TO CONSTRUCT. 4)IT HAS LOW NUMBER OF COMPONENTS THEREFORE, IT A CHEAP APART FROM THIS,.

18. Disadvantages of half wave rectifier THE HALF WAVE RECTIFIER HAS MORE NUMBER OF DISADVANTAGES AS COMPARED TO THE ADVANTAGES. SOME OF THEM ARE: 1. SINCE, POWER IS DELIVERED ONLY DURING ONE HALF OF THE CYCLE OF THE INPUT ALTERNATING VOLTAGE, THEREFORE, ITS POWER OUTPUT AND RECTIFICATION FREQUENCY IS LOW. 2. TRANSFORMER UTILIZATION FACTOR IS ALSO LOW. 3. THE DC OUTPUT POWER PRODUCED FROM THE HALF WAVE RECTIFIER IS NOT SATISFACTORY TO MAKE A GENERAL POWER SUPPLY.

19. Full wave rectifier A FULL WAVE RECTIFIER IS A CIRCUIT, WHICH CONVERTS AN AC VOLTAGE INTO A PULSATING DC VOLTAGE USING BOTH HALF CYCLES OF THE APPLIED AC VOLTAGE. IT USES TWO DIODES OF WHICH ONE CONDUCTS DURING ONE HALF CYCLE WHILE THE OTHER CONDUCTS DURING THE OTHER HALF CYCLE OF THE APPLIED AC VOLTAGE.

20. Classifications of full wave rectifiers IT IS DIVIDED IN TO TWO TYPES: 1.CENTER TAPPED FULL WAVE RECTIFIER. 2.FULL WAVE BRIDGE RECTIFIER.

21. Centre tapped full wave rectifier IN THE CASE OF CENTRE-TAP FULL WAVE RECTIFIER, ONLY TWO DIODES ARE USED, AND ARE CONNECTED TO THE OPPOSITE ENDS OF A CENTRE- TAPPED SECONDARY TRANSFORMER AS SHOWN IN THE FIGURE BELOW. THE CENTRE-TAP IS USUALLY CONSIDERED AS THE GROUND POINT OR THE ZERO VOLTAGE REFERENCE POINT.

22. Full wave bridge rectifier A BRIDGE RECTIFIER IS AN ALTERNATING CURRENT (AC) TO DIRECT CURRENT (DC) CONVERTER THAT RECTIFIES MAINS AC INPUT TO DC OUTPUT. BRIDGE RECTIFIERS ARE WIDELY USED IN POWER SUPPLIES THAT PROVIDE NECESSARY DC VOLTAGE FOR THE ELECTRONIC COMPONENTS OR DEVICES.

23. Full wave rectifier theory: THEORY : A FULL WAVE RECTIFIER IS A CIRCUIT, WHICH CONVERTS AN AC VOLTAGE INTO A PULSATING DC VOLTAGE USING BOTH HALF CYCLES OF THE APPLIED AC VOLTAGE. IT USES TWO DIODES OF WHICH ONE CONDUCTS DURING ONE HALF CYCLE WHILE THE OTHER CONDUCTS DURING THE OTHER HALF CYCLE OF THE APPLIED AC VOLTAGE.

24. Advantages  RIPPLE FREQUENCY IS TWO TIMES THE INPUT FREQUENCY.  THE OUTPUT AND EFFICIENCY OF CENTRE TAP FULL WAVE RECTIFIER ARE HIGH BECAUSE AC SUPPLY DELIVERS POWER DURING BOTH THE HALVES.  FOR THE SAME SECONDARY VOLTAGE BRIDGE RECTIFIER HAS DOUBLE OUTPUT.

25. Disadvantages  IT IS DIFFICULT TO LOCATE THE CENTRE TAP ON THE SECONDARY WINDING.  THE DC OUTPUT IS SMALL AS EACH DIODE UTILIZES ONLY ONE HALF OF THE TRANSFORMER'S SECONDARY VOLTAGES.  THE DIODES USED HAVE HIGH PEAK INVERSE VOLTAGE.  FULL WAVE RECTIFIER REQUIRES MORE DIODES TWO FOR CENTRE TAP RECTIFIER AND FOUR FOR BRIDGE RECTIFIER.  WHEN A SMALL VOLTAGE IS REQUIRED TO BE RECTIFIED THIS FULL WAVE RECTIFIER CIRCUIT IS NOT SUITABLE.

26. parameter Half wave rectifier Centre tapped full wave rectifier Full wave bridge rectifier DC OR AVERAGE LOAD CURRENT (I LDC ) Dc or average load voltage Rms load current (I lrms ) Rms load voltage (v lrms ) Dc load power (p dc ) Max. rectification efficiency 01.2% 81.2% Ripple factor 48% COMPERISION OF RECTIFIER CIRCUIT