EE 136 Final Presentation Professor Dr. Zhou Presented by: Cynthia David

Agenda Part 1, Chapter 22 Centering of Auxiliary Output Voltages on Multiple-Output Converters. Part 1, Chapter 23 Auxiliary Supply Systems Part 1, Chapter 24 Operation of Voltage-Stabilized Power Supplies

Centering Auxiliary Output Voltages on Multiple-Output Converters Problem Obtaining an absolute output voltage value. Solution Saturable reactors – small toroids Used to control voltage and current control. Provides pulse width / timing techniques

Centering Auxiliary Output Voltages on Multiple-Output Converters Saturable Reactors Saturable Reactors with a forward converter. with a forward converter. Vout = Vs × ton / ( ton + toff ) from Chapter 21 Part 1 Example Example Given Vout = +12, -12, +5 Desire: 11.5 turns use 12 Higher Output Voltage is given ie ton = 15 µs toff = 18 µs

Centering Auxiliary Output Voltages on Multiple-Output Converters Saturable Reactors Saturable Reactors td = ton – required V × ton / (actual Vout ) = 15 - (12*15) / (12.7) =.827 µs td is delay time, ton is on cycle, Vs = Vout ( ton + toff) / ton = 27.9 V. td = Np × ∆B × Ae / (Vs) Np is the primary turns, ∆B difference in remanance flux from flux density saturation. Ae is the effective area of the core. Given ∆B =.4 Ae = Vs × td / ( Np × ∆B ) assume Np = 1.

Centering Auxiliary Output Voltages on Multiple-Output Converters Saturable Reactors Saturable Reactors Ae = Vs × td / ( Np × ∆B ) assume Np = 1. = 27.9*.827 µs / (1 *.4) = 57.7 mm^2

Centering Auxiliary Output Voltages on Multiple-Output Converters Applications Applications large industrial furnaces, welders and high-power voltage regulators. large industrial furnaces, welders and high-power voltage regulators. Important Concept Important Concept Depending on application, with saturable reactors, decide to alter the area or number of turn ratios to produce Vout. Depending on application, with saturable reactors, decide to alter the area or number of turn ratios to produce Vout.

Auxiliary Supply Systems Provide power for control Drive circuits within the main switch-mode unit. Need to be common to input and output lines. Safety factors must be given Creepage distance, isolation requirements Creepage distance, isolation requirements Auxiliary supply methods must be considered Auxiliary supply methods must be considered

Auxiliary Supply Systems Various auxiliary supply units Various auxiliary supply units 60 Hz Line Transformers 60 Hz Line Transformers Energized before the main converter, allows power available to the main switching mode. Energized before the main converter, allows power available to the main switching mode. Meets insulation and creepage requirements. Meets insulation and creepage requirements. Disadvantage: size & cost Disadvantage: size & cost

Auxiliary Supply Systems Auxiliary Converters Auxiliary Converters Two auxiliary power supplies from high frequency flyback converters. Two auxiliary power supplies from high frequency flyback converters. + More efficient because energy Is returnted to the supply during Flyback period.

Auxiliary Supply Systems Stabilized Auxiliary Converters Stabilized Auxiliary Converters Modifications Zener Diode,Q2, winding P3 Modifications Zener Diode,Q2, winding P3 Maintains constant frequency Maintains constant frequency + Maintains constant frequency. Can Be used as a clock.

Auxiliary Supply Systems High-efficiency auxiliary supply. High-efficiency auxiliary supply. Includes a bridge rectifier supply the converter & fan application Includes a bridge rectifier supply the converter & fan application + Most efficient supply system + Useful in V applications

Parallel Operation of Voltage- Stabilized Power Supplies Voltage Stabilized Power Supplies Voltage Stabilized Power Supplies connected in parallel with high voltages connected in parallel with high voltages usually have small output resistances usually have small output resistances big difference in current load! big difference in current load! desire equal distribution in current desire equal distribution in current may cause output power supply to be overloaded! Domino Effect! may cause output power supply to be overloaded! Domino Effect!

Parallel Operation of Voltage- Stabilized Power Supplies Configurations of Power Supplies Configurations of Power Supplies Master Slave Operation Master Slave Operation Master controls the parallel supplies. P- terminal and Transistor 3 control current Master controls the parallel supplies. P- terminal and Transistor 3 control current KEY POINTS + Similar output current - 20% Accurate - Limited to the number of supplies - If Master Fails, other units follow

Parallel Operation of Voltage- Stabilized Power Supplies Configurations of Power Supplies Configurations of Power Supplies Voltage – Controlled Current Source Voltage – Controlled Current Source P terminal link adjust for output voltage, R1 and R2 sense output current. P terminal link adjust for output voltage, R1 and R2 sense output current. KEY POINTS + More accurate output current - Less percent of failure

Parallel Operation of Voltage- Stabilized Power Supplies Configurations of Power Supplies Configurations of Power Supplies Force Current Sharing Force Current Sharing Compares Vref and V from R3 and R4 to maintain constant Voutput. Compares Vref and V from R3 and R4 to maintain constant Voutput. A2 compares the currents and Rx alternates alters V2 and Vout. A2 compares the currents and Rx alternates alters V2 and Vout. KEY POINTS + More accurate output current + Failure to one does not affect others. + Redistribute load if others fail. + Output voltage adjust itself to the average value of the independent units.

Parallel Operation of Voltage- Stabilized Power Supplies Configurations of Power Supplies Configurations of Power Supplies Parallel Redundant Operation Parallel Redundant Operation Ensures maintenance of power in case supply fails. Ensures maintenance of power in case supply fails. Diodes senses differences in Voutput. Diodes senses differences in Voutput. KEY POINTS + Failure to one does not affect others. + Redistribute load if others fail

Conclusion Review Review Centering of Auxiliary Output Voltages on Multiple-Output Converters Centering of Auxiliary Output Voltages on Multiple-Output Converters Auxiliary Supply Systems Auxiliary Supply Systems Parallel Operation of Voltage Stabilized Power Supplies. Parallel Operation of Voltage Stabilized Power Supplies.