Common DC bus energy feedback speed control system (hereinafter referred to as common bus feedback system) adopts a separate rectifier/feedback unit, in order to provide a certain power of DC power supply, the speed control inverter is directly connected to the DC bus. When the system works in the electric state, the inverter obtains electric energy from the bus. When the system works in the power generation state, the energy is directly fed back to the power grid through the bus and feedback unit, so as to achieve energy saving, improve the reliability of equipment operation, reduce the amount of equipment maintenance and equipment footprint.

The main hardware parts of the common DC bus energy feedback frequency conversion speed control system include active rectifier/feedback unit and inverter.