Double-feedback control with stepless variable speed driving technology by sensing refrigerant pressure and indoor temperature applied to air conditioning system

Abstract

An energy-saving strategy of variable refrigerant volume (VRV) is proposed for air conditioning systems by using the stepless variable speed driving technology. This control technology is applied to the air cooled packaged water chiller unit (ACH) according to the change of environmental heat load to achieve the best amount of refrigerant in real time. This study designs a double feedback Stepless Variable Frequency and Variable Refrigerant Output (DFSVFVRO) for controlling ACH. The double feedback variable frequency control uses both temperature and the pressure sensors as feedback signals to the control board and the frequency of the compressor is regulated by the inverter. Experimental results indicate that the proposed variable frequency control method has a lower energy consumption compared with the conventional normal mode (N). In addition, the proposed double feedback mode (DF) has a lower energy consumption, and thus, it is with better energy efficiency. Furthermore, in the various experiments of proposed DFSVFVRO by comparing the cumulative energy consumption of DF mode with N mode, the DF mode shows an energy saving rate of at least 25%. It also verifies that the double feedback variable frequency control method has a better energy-saving benefits than that of the single feedback frequency.