Research On Design Of Dual Stator-Winding Induction Generator And Control Of System

Wind generating system and high voltage DC stand-alone supply system of aviation and tank have presented new demands for induction generator. The dual stator-winding induction generator is presented for these demands. Two sets of three-phase windings are embedded in the stator slots, the one referred as power winding with excited capacitors C, supplies power to DC load via a bridge rectifier. The other termed the control winding, is connected PWM excited converter, which supplies only the reactive power and none of active power to control the output voltage stable. Solving the problem of large varying excited current adjusting of induction generator with variable load and speed. By the optimal design of machines parameters and excited capacitor and proper control strategy, the minimal capacity converter can be used to control large power output or the minimal current of converter can be used to control large current output under wide speed range and load, which reduces the cost,volumes and weight of system .Both the two sets of windings have none of electrical connection but magnetic coupling exiting, so the harmonic from the converter of control winding has little disturbance on the load, and the electromagnetic compatibility and efficiency have been improved more.The general mathematic model and equivalent circuit under axis of dq and abc reference of dual stator-winding induction machine with rectifier load are derived. The physical process inside machine is proposed. The operational mechanism of the system is revealed. Electromagnetic torque and motional equation and basic characteristic expression are given.The analytical calculations of slot and harmonious leakage reactance of dual stator-winding induction machine with different winding structure, such as double single-layer and three-layer and four-layer, are presented systematically, the relevant formulas with different pitch are derived, and generalized to m-phase machines. The decouple of dq axes leakage reactance between of the two sets of windings is studied. These conclusions will provide theoretical guidance to the winding distributing and parameters calculating.The operational laws of this system under variable speed are studied firstly. The capacity ratio between control winding and power winding is proposed. The relation between reactive capacity and parameters of machine, load, rotating speed, speed ratio and exciting capacitors is analyzed. The distribution of reactive power with variable speed and laws of winding's currents are given. The determination of excited capacitors to minimize the reactive power of control winding under variable load and speed is given. The optimal strategy of minimal capacity converter can be used to control large power output is studied. The simultaneously optimal design concept of dual stator-winding induction generator and excited capacitor with wide speed range is researched, which the machines parameters and excited capacitor are simultaneously optimized to make the minimizing to reactive power of excited converter. The designing features of high voltage DC induction generator are given. The design formulae and processes and collating means based circuit and magnetic path are presented. The CAD are designed by complex method with dynamic full reflection and retraction operator. A prototype of 18kW and 270V high voltage DC is designed, The parameters effects on the capacity of control winding is analysised, and finite element method is given.The improved real-coded genetic algorithm is used to test the designed results theoretically. The results show this scheme has prominent effect to reduce reactive power of control winding, and the capacity of converter can be reduced to 1/3 of output rated power, which makes the cost, dimension of inverter much smaller.The special design strategy of minimal current converter can be used to control large current output is studied. When the output voltage of power winding is very low and the output current very high,the winding turns ratio between the two winding is choosed to reduced the current of control winding.The excited capacitor can be canceled.These can reduce the cost and volume of the system.The universal simulation model of dual stator-winding induction generator system is established by MATLAB/SIMULINK. The starting-up process by the PWM excitation converter is resolved. And the performances of steady and dynamic operation with variable speed are simulated based direct flux stator control of control winding. The performances under resistor load and bridge rectifier are compared.The Real-time experimental model based dSPACE is setup, and the experiment is done with a 18 kW and 270V rectified DC output prototype. The experiments are done under different load and different capacitors and 1:2 speed ratio. The experimental results are anastomose with those of simulating, which validates the control winding current laws and the optimal strategy. The operational laws of the system with variable load are experimented.