Variable- voltage and variable- frequency controllers are gaining more significance in the present industrial applications. These controllers are widely appreciated for its flexibility. This paper attempts to present the design for the above controller using pulse width modulation technique and FPGA (Field programmable gate arrays). To maintain maximum torque for a given working condition, the flux in the machine must be maintained constant. In other words, the ratio of Voltage to frequency must be held constant. The fundamental component of the inverter output has to be checked. To vary the fundamental component of the inverter, the Modulation Index of the carrier signal has to be changed. The application part of it is wide.

Keywords : FPGA; Modulation Index; VVVF