An AT89C52 Microcontroller Based High Resolution PWM Controller for 3-Phase Voltage Source Inverters

A novel technique for generating real time high resolution pulse width modulated patterns for a three phase voltage source inverter is presented in this paper. An AT89C52 microcontroller computes the PWM pulse widths on carrier cycle basis based on the input frequency. The microcontroller send the pulse width information for the three phases to a memory minimized ROM lookup table, which is scanned by a binary counter to generate the real time PWM patterns. The on board timer of AT89C52 is utilized to generate programmed clock for the scanning binary counter. The overall design is hardware minimized and compact that makes it feasible for low cost high performance ac drive applications. The proposed PWM controller supports variable frequency variable voltage operation for wide range and hence is ideally suited for industrial drives requiring wide speed variations. Keywords: Pulse width modulation, Microcontroller application, Voltage source inverter, variable speed ac drives.