DPF 500 pulses electronic expansion valve is a kind of promising throttling device suited for the demands of mechano-electronic refrigeration system. It can give fast response and a wide modulating range. Moreover, it can work under the preset modulating method to achieve the excellent quality of superheat modulation. So it can guarantee the chiller to be used efficiently and the system to be run with steady-state, low energy losses and accurately controlled temperature. It is used widely in refrigeration system such as inverter air conditioners.