Abstract：At present, fans, pumps are widely used in the national economy of production equipmen and the field of electricity, water treatment, water supply, urban heating, metallurgy, mineral, port machinery, petroleum chemical industry, the power consumption is large, accounting for almost half of the industrial electricity consumption. At present, the majority of fans, pumps use valve or baffle to adjust the flow to meet the requirements of the load changes, or the use of inefficient speed control, but this way has a serious waste of energy.
On the basis of the objective analysis of the status of the fan or pump load speed technology ‘s development. This paper is in case of Conventional cascade speed control system with low power factor, combined with the specific reality of the double-fed motor energy saving speed control，a detailed discussion had been made about the chopping cascade speed control system design and had a analysis and calculation of the mechanical properties of the various links of the system parameters and system.. A double-fed motor chopping cascade speed control system was designed. The speed control system uses insulated gate bipolar transistor ((IGBT) as the DC chopper and the speed and current closed-loop control are used. In the system the speed can be controlled by the way to control the duty cycle of the chopper to change the additional potential of rotor circuit.
Key words：Doubly fed motor; Cascade control; Chopper;MATLAB Simulation