Digitization Freqency Controller For Three-phase Induction Motors

Due to non-linear and close coupling of three-phase induction motor, deducting transfer function in variable frequency based speed control is a difficult task. Besides, the efficient value of voltage use of based on traditional U/F control mode is quite low. Therefore, this paper proposes a new control method for three-phase induction motor by combining space voltage vector PWM (SVPMW) with fuzzy PID algorithm.In the hardware circuit, 16-bit embedded microcontroller dsPIC30F6010 of Microchip with DSP core, dedicated specially designed for motor control, has been adopted. The system is designed by making full use of dsPIC30F6010-chip periphery circuit to reduce the hard cost. This part introduces the principle to select the CPU for the embedded system, the general outline for the hardware circuit and main functional module. To guarantee the reliability of the system, this work designed an architecture consisting of main board and driving board according to isolate heavy current and the weakness.Emphatically, fuzzy PID algorithm, space voltage vector PWM(SVPWM) and power protection have been introduced in detail in software design part. In order to gain the control performance, the Mamdani reasoning method is employed based on fuzzy PID algorithm and space voltage vector is regulated according to its output. Supported by this processor hardware, the power-fail protection is easy to implement.At the last part, this system is used in metering pump control system as well as in compressor control system of vending machine. The test results show the efficiency of three-phase induction motor based on fuzzy PID control combined with space voltage vector PWM (SVPWM).