In this system, two 110KW chilled water pumps are driven by two D71 110KW inverters, and there are also several D71 inverters that drive fans (including indoor fans and cooling tower fans). In the chilled water circulation system, the signal 1 (temperature signal or pressure signal) of the water inlet circuit and the signal 2 (temperature signal or pressure signal) of the water outlet circuit are sent to the analog module to obtain the analog feedback signal of the inverter. Through the built-in PID function of the inverter, the closed-loop automatic control is realized.