Asymmetrical Noncomplementary Modulation Strategies for Independent Power Control in Multioutput Resonant Inverters

Domestic induction heating (IH) design trends aim at improving user experience by increasing the cooking surface flexibility while maintaining a cost-effective implementation. The design of multioutput topologies is a key development for this purpose. However, due to their complexity, output power control usually relies on low-frequency pulse density modulations that, in addition to the slow response due to significant power averaging times, present severe restrictions as a consequence of power pulsation regulations. This article proposes two different noncomplementary asymmetrical modulation strategies that allow continuous operation avoiding both flicker and heating performance issues and obtaining a fast-response load power control. In order to prove the feasibility of the proposed modulations, a prototype featuring 12 IH loads of 2000-W maximum rated power has been built, and both strategies have been tested.