1. Power Sources Utility: 60 Hz - 120/240 V - 1,2,3 Phase Fixed Voltage Batteries Fuel Cells Photo Voltaic Thermionic Generators AC generators (“Alternators”) – variable frequency DC Generators

2. Electrical Consumption AC motors – sync/async DC Motors Residential Heating/Cooling Lighting AC/DC High frequency Induction Heating HF Electronic Systems – Fixed Voltage DC Transmission Losses Conversion Losses

3. Replacement of Legacy Technologies Automotive (Electric Vehicle Propulsion) Hydraulic controls (Fly by wire) Tele - commuting, tele - presence Beam Weapons Unmanned Aircraft

4. Critical Converter Parameters Efficiency Weight Size/Volume Power handling Capacity Power Density Cost

5. Photo-voltaic Cells

6. Us N Type Dopants P Type Dopants

7. P N PN Junction Diode Doping Profile P N Diffusion Result Depletion Region Hole Diffusion Electron Diffusion + + + - - - Equilibrium Charge Displacement Internal E-Field Resulting from Charge Displacement Inhibits Further Diffusion - Photon Generated Hole/Electron Pair E- Field Accelerates Electron and Hole I SS (Proportional to photon flux) Equivalent effect of photon generated internal current. +

8. Resistive Load - V SS + I SS (Proportional to photon flux) IJIJ Shockley’s Equation: Photo-voltaic Cell V SS IJIJ

9. Hyperbolic Curve P1P1 P 2 > P 1 To get maximum power out of the photovoltaic cell, the converter must make the cells see 0.403 ohms when I SS = 1.5 amps! Power Converter Load: R = ? Photovoltaic Array To make matters worse, P Opt and R Opt vary with temperature as well as I SS !

10. Maximum Power Condition: Curves are Tangent … which converges to ~ 0.1% in 4 or 5 iterations, but will be ~ 0.6 V for almost any reasonable conditions... so to hell with the math!

11. In full sunlight, the solar energy flux is ~ 1Kw/m 2, and 15% efficiency is normal, so I SS in amperes, A Cell in m 2.

12. General Power ConverterDefinitions Efficiency: Power Density How much power can be delivered by a “small” package and not have it overheat?

13. Example Your trusty mechanical engineer has designed a cooling scheme that will allow a package having a volume of 0.027 m 3 to dissipate 150 watts and keep the interior components below 55C. Determine the power output capability and power density if your electrical design exhibits efficiencies of 80% and 90%. 80% 90%