1. INVERTERS: The Investigation to the*
INVERTERS: The Investigation to the
07/16/96
optimal topology to the designing of a
sinewave inverter range for the use in
static as well as mobile applications
Presenter: Dr Gawie van der Merwe *

2. *
Background
07/16/96
PV and Mobile Inverters with a sinewave output is the optimal requirement.
Various Topologies exist.
Investigations done in order to search for the optimal topology.
Investigation towards:
Efficiency
Cost
Reliability
Manufacture (Complexity/Simplicity) *

3. Sinewave Inverter Topologies*
Sinewave Inverter Topologies
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CVT (Constant Voltage Transformer)
50Hz Transformer
Push Pull Primary-
Full Bridge switching in Primary with series line Inductor
High Frequency Isolation Transformer and Secondary H-Bridge Control
Series or Parallel Transformer switching *

4. A) Constant Voltage Transformer*
A) Constant Voltage Transformer
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(Ferro Resonant Transformer) *

5. B) 50Hz - Transformer Topology*
B) 50Hz - Transformer Topology
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Various “50Hz” transformer topologies exist
Push-pull - Inductor in primary
Push-pull - Inductor in secondary
Full Bridge Inductor in primary *

6. *
07/16/96 *

7. *
Topology B1
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Push-pull - Inductor in primary *

8. Push-pull - Inductor in primary*
Topology B1
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Push-pull - Inductor in primary
Advantages
Simple manufacture & design
Mosfet drive circuit referred to ground
Disadvantages
Voltage overshoot over devices - leads to voltage rating increase - Reduction in efficiency
No-, or limited control over free running inductor current
“Skewing” of transformer often occur. *

9. Topology B2 Push-pull - Inductor in secondary*
Topology B2
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Push-pull - Inductor in secondary
Primary side Push-pull, series inductor in secondary *

10. Push-pull - Inductor in secondary*
Topology B2
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Push-pull - Inductor in secondary
Advantages
Simple manufacture & design
Mosfet drive circuit referred to ground
Disadvantages
Voltage overshoot over devices - leads to voltage rating increase - Reduction in efficiency
No-, or limited control over free running inductor current
“Skewing” of transformer often occur. *

11. Topology B3 Full Bridge Inductor in primary Most popular used topology*
Topology B3
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Full Bridge Inductor in primary
Most popular used topology *

12. Full Bridge Inductor in primary*
Topology B3
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Full Bridge Inductor in primary
Advantages
Complete control over primary side inductor current
Uni-as well as bi-polar pwm control strategy possible
Simple manufacturing
Disadvantages
System design is more complex
Inverter efficiency is load dependent *

13. C) High Frequency Isolation*
C) High Frequency Isolation
07/16/96 *

14. *
07/16/96
C) High Frequency Isolation Transformer with full H-bridge Control on Secondary
High frequency isolation reduce physical size
Direct output control leads to better output waveform control and reduced distortion *

15. *
07/16/96 *

16. High Frequency Isolation Transformer*
High Frequency Isolation Transformer
07/16/96
Advantages
Units generally more mobile
Possible to limit battery current drawn to a “smooth DC”
Good efficiency with a non linear load
Disadvantages
Design is complex
Manufacture is complex
High cost *

17. D) Transformer - series and/or parallel switching*
D) Transformer - series and/or parallel switching
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A wide range of topologies exist
A combination of various Transformer switching topologies
Transformer secondary is in series
Separate output voltage & frequency for each transformer *

18. Transformer-series and/or parallel switching*
Transformer-series and/or parallel switching
07/16/96 *

19. *
07/16/96 *

20. Transformer -series and/or parallel switching*
Transformer -series and/or parallel switching
07/16/96
Advantages
High running to overload ratio is
Very popular design
Advantages for motor startup
High efficiency
Disadvantages
Control complex
Manufacturing is complex
Inverter is big and bulky *

21. Summary Matrix transformer topology*
Summary
07/16/96
Different topologies have advantages for different applications
Both topology A, B1&B2, (50Hz topology) are outdated
High frequency option, has mobility & weight advantage
Output distortion under all conditions low
Matrix transformer topology
Physical dimensions restrains mobility
Ideal for short period overload power peak/Mass ratio is good *

22. Estimated Inverter Manufacturing Costs (Same Input Power Stage)*
Estimated Inverter Manufacturing Costs (Same Input Power Stage)
07/16/96
Input power stage same for comparing
Calculation done on continues rating without forced air cooling
Cost calculated on discreet units *

23. Non linear load as a % of total power consumption*
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Non linear load as a % of total power consumption
Non linear loads - high percentage on power application below 1Kva typical loads, computer, fluorescent lights, video
Higher power application, more resistive, i.e. Microwave, Hairdryer etc.
< 1Kva most sensitive to PV applications *

24. *
07/16/96 *

25. Topology Suggestions for Power Levels*
Topology Suggestions for Power Levels
07/16/96
Power Rating
High Frequency
Full Bridge 50Hz
Matrix Config. W
Mobile (most cost efficient)
50%
Advantage on
perm installation
60%
Too expensive
10%
400W-1500W
Mobile General
70%
PV-Permanent
100%
40%
1000W-2,5Kw
PV-Permanent
70%
PV & Mobile
Stackable units in parallel 70%
PV Permanent
Best choice 80%
2Kw-5Kw
Stackable parallel combination 100%
Stackable Units
80%
Mobile
30%
(Percentage indicates topology choice for the application) *