FPGA-based power measuring for induction heating appliances using sigma-delta A/D conversion

This paper presents a field-programmable gate array (FPGA) implementation of a digital circuit that measures in real time the output power of medium-frequency (25-50 kHz) induction-heated cooking appliances. The voltage and current are sensed using first-order sigma-delta ([SIGMA][DELTA]) analog-to-digital converters. The power-measuring algorithm is very simple while maintaining good accuracy. The algorithm is developed using a hardware description language (VHDL). The digital circuit, the power converter, the signal conditioning circuits, and the [SIGMA][DELTA] modulators are simulated all together using a mixed-signal (analog + digital) simulation tool. The algorithm error is obtained in simulation computing the average power using VHDL-Analog and Mixed-Signal Extension Language (VHDL-AMS), and the influence of different parameters is analyzed. Finally, the digital circuit is implemented in the FPGA, and the simulations are experimentally verified. Index Terms--Analog-to-digital (A/D) conversion, field-programmable gate arrays (FPGAs), hardware design languages, induction heating, power measurement, sigma-delta ([SIGMA][DELTA]) modulation.