Power Measurement for Resonant Power Converters Applied to Induction Heating Applications

Nowadays, induction heating (IH) technology is dominating the domestic cooking market due to its advantages such as safety, cleanness, and high efficiency. Such high efficiency and high power density implementations are achieved by means of resonant power converters and, consequently, these need to be accurately controlled. This paper proposes a field-programmable gate array-based online power measurement system which allows the control system to perform the proper power control. The proposed power measurement system measures the output power from the digitized output voltage and current through two low-cost 1-bit second-order ΣΔ analog-to-digital converters. The bitstreams have been analyzed and, taking into account the results, several measurement approaches have been proposed and analyzed. Then, a noise sensitivity analysis has been performed in order to verify the proposed measurements methods. The analytical and simulation results have been tested through a resonant power converter applied to domestic IH whose switching frequency varies from 30 to 80 kHz. A statistical analysis of the implemented measurement approaches has been carried out in order to evaluate the system accuracy. Finally, the selected measurement method has been verified for several vessels. As a conclusion, an accurate and cost-effective output power measurement system is obtained, which can be applied to any resonant converter in the frequency operation range.