1. EET 423 POWER ELECTRONICS -2
Prof R T Kennedy
POWER ELECTRONICS 2

2. IDEAL TRANSFORMER MAGNETIC DEVICE ELECTRICAL ISOLATION FUNCTION:
TRANSFER ENERGY
SCALE CURRENT and VOLTAGE TRANSFER
NO ENERGY STORAGE
Prof R T Kennedy
POWER ELECTRONICS 2

3. REAL TRANSFORMER SOME ENERGY STORAGE
MAGNETISING INDUCTANCE (WITHIN CORE)
minimised by using gapless core
minimised by using high permeability core
LEAKAGE INDUCTANCE (EXTERNAL to CORE)
Prof R T Kennedy
POWER ELECTRONICS 2

4. TRANSFORMER PARASITICS
Prof R T Kennedy
POWER ELECTRONICS 2

5. TRANSFORMER LIMITATIONS
LOW FREQUENCY
core saturation
SMPS FREQUENCIES
core loss
Prof R T Kennedy
POWER ELECTRONICS 2

6. FLYBACK CONVERTER TRANSFORMER
BASICALLY MULTI WINDING COUPLED INDUCTOR
energy storage in non-magnetic gap
energy recoverable
DESIGN LIMITATIONS
core + winding losses  temperature rise & efficiency
fixed b core losses reduce with temperature increase
core saturation
saturation flux density reduces with temperature increase
leakage inductance
Prof R T Kennedy
POWER ELECTRONICS 2

7. FLYBACK CONVERTER TRANSFORMER
Prof R T Kennedy
POWER ELECTRONICS 2

8. FORWARD CONVERTER TRANSFORMER
NORMAL TRANSFORMER
NO energy storage ideally
leakage inductance represents
energy stored in non-magnetic regions
mutual inductance represents stored energy in core
DESIGN LIMITATIONS
core losses
leakage inductance
Prof R T Kennedy
POWER ELECTRONICS 2

9. FORWARD CONVERTER TRANSFORMER
Prof R T Kennedy
POWER ELECTRONICS 2

10. LEAKAGE INDUCTANCE EFFECTS
Prof R T Kennedy
POWER ELECTRONICS 2

11. FLYBACK TRANSFORMER
Magnetising Current is important in flyback transformers (& inductors)
represents
Energy Storage requirements
Leakage Inductance is a parasitic
Prof R T Kennedy
POWER ELECTRONICS 2

12. FERRITE CORE TOROIDAL TRANSFORMER
Prof R T Kennedy
POWER ELECTRONICS 2

13. Prof R T Kennedy
POWER ELECTRONICS 2

14. REDUCE LEAKAGE INDUCTANCE
Prof R T Kennedy
POWER ELECTRONICS 2

15. Prof R T Kennedy
POWER ELECTRONICS 2

16. LOW OUTPUT VOLTAGE HIGH OUTPUT CURRENT
Prof R T Kennedy
POWER ELECTRONICS 2

17. OUTPUT CURRENT SHARING
Prof R T Kennedy
POWER ELECTRONICS 2

18. HIGH EFFICIENCY
Prof R T Kennedy
POWER ELECTRONICS 2