Frequency control technology can achieve the purpose of energy saving of power equipment, but also bring problems of harmonic loss formula. The relationship between the loss rate and load rate is constituted by formula derivation, and calculate the load rate when the loss rate is the minimum and the total power of power-consuming devices. Then design the digital PID controller and research the power-saving optimization feedback algorithms and design the software process. Finally, carry out the inverter switching algorithm based on ABB ACS510 low voltage inverter.