Air Conditioner Inverter Systems

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The Inverter tag found on some air conditioners signifies the ability of the unit to continuously regulate its thermal power flow. Traditional reverse-cycle air-conditioners use a heat pump that is either working at maximum capability or switched off, as the compressor's speed cannot be varied. In order to regulate temperature a thermistor is used to measure the ambient air temperature and switch the compressor on when the ambient air temperature is too far from the desired temperature. Air-conditioners bearing the Inverter tag use a rectifier to convert the incoming AC current to DC and then use Pulse-Width Modulation of the DC current within an inverter (electrical) to produce AC current of a desired frequency. As the speed of a brushless motor is synchronised to the frequency of the AC current it is thus possible to build a compressor that can be run at different speeds. A microcontroller can then sample the current ambient air temperature and adjust the speed of the compressor appropriately. The effect of eliminating stop-start cycles is to increase efficiency, extend the life of air conditioning components and eliminate sharp fluctuations in the load the air-conditioner places on the power supply.