Graphs showing the comparison of Temperature variation of NPP and Active NPC at different frequencies
solar inverters
Fig 6 : shows the output power graph
Graphs showing the comparison of THD variation of NPP and Active NPC at different frequencies Fig 7 : shows the THD graph
Neutral Point Balancing Control Strategies : I) DC Voltage injection Method DCMLI has inherent problem of unbalanced voltages across dc link capacitors due to load unbalancing, non ideal properties of dc link capacitor. Unbalanced dc link voltage results in oscillations in the system and dc bus capacitance. It also distorts the output voltage. In order to avail these, the dc link capacitor must be confined to half of the total dc link voltage. This gives balancing of the capacitor.
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Comparison table of NPP and Active NPC Sl. No. NPP Active NPC 1 3-level output voltage 3-level output voltage Equal distribution of 2 Unequal distribution of losses due to the more losses at the switches switching states. Switching losses and 3 Switching losses and THD are less THD are more Due to the new 4 As this is in usage from controlling strategies the past years the size applied to this the size and volume of the and volume is less inverter is more 5 6
Used for medium speed drives at low voltage Applications of these in the industry are more compared to ANPC
Used for high speed drives at high voltages Usage in the industry is less as it is still in research for its better result but its applications are for high performance
7
Cost of this inverter is less compared to ANPC
Due to the new controlling techniques cost of this inverter is more
EQ
June-July 2015
43Â