FPGA BASED SPACE VECTOR MODULATION FOR V/F CONTROL

Abstract

Voltage Source Inverter (VSI) is the most widely utilized power converter in Industrial Drive Systems. The voltage and frequency Control of the inverter output is achieved by using PWM techniques. Space Vector Pulse Width Modulation (SVPWM) provides better DC bus utilization and minimum switching losses as compared to other PWM techniques. These PWM signals are generated using DSP or FPGA. The FPGAs provide higher computational speed and flexibility due to their reconfigurable hardware. This work basically deals with implementation of SVPWM algorithm on FPGA. The 3-phase sine wave is first digitized and stored in the form of a lookup table. The reference vector is generated from 3-phase references (voltages) using d-q transform. Reference vector Vref is sampled with frequency 1 KHz. Width of pulse is modified by varying magnitude and rotating frequency of reference vector depending on applied inputs. The method has been presented to reduce complex timing equations to a simplified form which avoids trigonometric mathematical operations in the algorithm. An algorithm was implemented in such a way that the consecutive switching vectors undergo single bit state change which reduces switching losses.