Defrosting of inverter-driven air conditioning plant - using outdoor measured temperature to initiate defrost, with compressor frequency controlled to give constant defrost time

摘要

A procedure is provided for defrosting an inverter-driven air conditioning unit where the rime on the outdoor heat exchanger is melted off. First, it is determined whether the temperature measured by a sensor on an outdoor duct is appropriate for the initiation of defrosting and then a four way valve is adjusted to block the flow of cooling medium so that the defrost cycle can commence. Next, the defrost condition is evaluated and the compressor drive frequency and heating element phase are changed so that the defrosting takes a preset time dependent on the measured temperature. The defrosting process is then monitored continuously with adjustments in these two parameters if necessary. ADVANTAGE - Defrost time determined by measured temperature of outdoor duct.