Date post: | 13-Dec-2014 |
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Applications◦ Standby source for “critical” loads (computer)◦ Primary source when normal ac not available
Uninterrupted Power Supply (UPS)◦ 2 common configurations
Normal condition◦ Main supply applied to the load◦ Rectifier keeps batteries charged
Main supply failure◦ Inverter supplies power to the load◦ When interruption is over, main supply is
applied to the load
Normal condition◦ Inverter operates continuously, powering the
load◦ Rectifier maintains the charge on the batteries◦ Inverter conditions the supply to the load
Inverter failure◦ Main supply powers the load
Main supply failure◦ Battery supplies the inverter ◦ Inverter powers the load
Normal conditions◦ Inverter operates as a bridge rectifier◦ Main supply powers the load
Switched-mode
Resonant
Bidirectional
Two inverters◦ Input side: operates at high-frequency◦ Reduces size of transformer and DC filter
components at the input of the output-side inverter
Two inverters continued◦ Output side: operates at output frequency
Two inverters◦ Input side is a resonant inverter◦ Output side operates with PWM control at the
output frequency
Output inverter and Rectifier are combined into a cycloconverter (converts one frequency ac into another frequency ac)
Power flow in either direction
Four conversions AC-DC – DC-AC – AC-DC – DC-AC Ultimately an AC – AC Conversion