Research On Vector Control For Double-fed Variable Speed System Based On Tms320f2812

With the development of economics, the demand for electric power is growing. Therefore, energy saving should be paid more attention while the capacity of the electric power expands. Load such as blower and pump, at different working state, can significantly reduce power consumption with speed control. Speed control system of doubly-fed motor can meet the requirement of changing speed while the capacity of inverter is one third of the capacity of squirrel cage motor. The control precision and the dynamic response of the motor can be achieved as vectoring control technique and digital control technique is used, the motor can be applied in electric drive area that need high control performance.At first, this paper introduces the overview development, advantages in industrial applications, prospect and problems that need solved of the doubly-fed machine. Target and content of the study is summed up according to requirements of speed regulation system.Secondly, according to the physical model of the double-fed machine, the mathematical model based on three-phase coordinate system is established, the mathematical model based on two-phase rotating coordinate system under the condition of constant power is derived. Decoupling control of the rotator speed and the stator excitation current is realized by the strategy of stator flux orientation control and flux tracking control is realized by space vector pulse width modulation.Variable-frequency starting technique by rotor side is introduced, torque characteristics of variable-frequency operation and double-fed operation is analyzed. According to the speed-control theory of double-fed machine, the flow of energy of working state including Sub-synchronous electric operation, Sub-synchronous feedback operation, Super-synchronous electric operation, Super-synchronous feedback operation and reverse pull down operation, is analyzed.Hardware of variable-speed system of double-fed machine, including signal detection circuit, control chip, drive circuit, communication circuit and protection circuit is detailed introduced and the type of chip used in circuit is illustrated. The C program based on TMS320F2812, including detection program of rotor position, SVPWM signal program and digital PI controller is achieved. Implementation and flow chart of each program is given.