Xantrex 120 VAC/60 Owner's Manual

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Xantrex 120 VAC/60 Owner's Manual Manual pdf 65 page image

OPERATION 2001 Xantrex Technology, Inc.5916 - 195th Street N. E.Arlington, WA 98223Telephone: 360/435-8826Fax: 360/435-2229www.traceengineering.comSW Series Inverter/ChargerPart No. 2031-5Rev. C: February 2001Page57OPERATIONThe SW Series Inverter/Charger can be configured as a simple stand-alone unit, working in conjunctionwith your generator to handle loads too large for the generator alone, allowing two-wire or three-wiregenerators to be turned on and off based on battery voltage or loads amp size, or functioning as a utilityinteractive inverter which will allow you to send excess power back to the utility grid. Often, the inverter willbe set-up to operate in several modes at the same or different times - such as operating as aninverter/charger in utility back-up mode with automatic generator control mode and generator supportmode during extended utility outage periods. The extensive configurations available are described in thissection will allow you to enhance and customize your inverter’s particular operation.Before operating the SW Series Inverter/Charger, ensure that the unit is installed in accordance with theinstructions in the INSTALLATION section beginning on page 15.THEORY OF OPERATIONThe SW Series inverters employ a new patented inverter design. This design uses a combination of threetransformers, each with its own low frequency switcher, coupled in series and driven by separateinterconnected micro-controllers. In essence, it is three inverters linked together by their transformers.Figure 17, Trace™ SW Series Inverter Simple Block DiagramBy mixing the outputs from the different transformers, a sine wave is produced. Shown in Figure 18, is theoutput waveform from a Trace™ SW Series Inverter/Charger. Notice the “steps” form a staircase that isshaped like a sine wave. The total harmonic distortion in this sine wave approach is typically 3-5%. Themulti-stepped output is formed by modulation of the voltage through mixing of the transformers in aspecific order. Anywhere from 34-52 “steps” per AC cycle are present in the waveform. The heavier theload or lower DC input voltage the more steps there are in the waveform.This type of inverter solves many of the problems associated with high frequency or ferroresonant sinewave inverters. The low frequency method described has excellent surge ability, high efficiency (typically85 to 90%), good voltage and frequency regulation, and low total harmonic distortion.The inverter runs in two basic formats: as a stand-alone inverter (converting DC to AC), or as a parallelinverter (with its output synchronized to another AC source). In inverter mode, only 60 Hz (50 Hz for exportunits) waveforms are created. As the battery voltage rises, waveforms with progressively fewer steps aregenerated. More steps are used when battery voltage decreases. Since the battery voltage tends to dropwith increased load, the waveform has increased number of steps with heavier AC loads.ACLoadsBatteryLowFrequencyH-BridgeLowFrequencyH-BridgeTransformerTransformerTransformerLowFrequencyH-BridgeBridges are “mixed” byMicro-ControllersControlling the H-Bridges.Micro-Controllers