The Research On Pwm Variable Frequency Techology Of Ac Variable-speed System

Using DSP of TI inc.-------TMS320F240 this thesis develops a general ACvariable-speed system, and then carries out the research on various new control strategies for induction motor based on it.This paper explains sine pulse width modulation(SPWM), space-vector pulse width modulation(SVPWM),and new pulse width modulation method-hybrid space vector pulse width modulation(HSVPWM) aiming at a inherent problem of dead time in the common pulse width modulation. In this paper, the formulas of calculating about three PWM variable-frequency technologies are deduced in the detail, and their correctness and validity are proved by experiment.As for hardware, TMS320F240 is the control unit. A piece of digital signal board and analog signal board based on EVM board of TMS320F240 are designed. Digital signal board mainly implements frequency giving, data display and so on. Analog signal board mainly detects current signals, voltage signals and implements fault protect. Main circuit adopts the AC-DC-AC structure and uses IPM(Intelligent Power Module) as main switch.The software implements sine pulse width modulation (SPWM), hybrid space vector pulse width modulation (HSVPWM) using assembly language of TMS320F240 and achieves the purpose of variable-frequency adjusting-speed for induction motor.