A Comprehensive Induction Heating Power System for Large All-Metal Cooking Pots With Energy Storage

Given the high-power requirements of commercial automatic cooking machines, a comprehensive all-metal induction heating (IH) power system with an energy storage port is proposed. The energy storage port serves to peak shave the IH system and utilizes time-of-use electricity pricing to save costs. While domestic IH is primarily used for ferromagnetic (FM) pots, there is a challenge with non-FM (NFM) pots due to their small equivalent resistance, which can easily cause overcurrent issues for inverters. To achieve all-metal heating, a dual-resonance topology inverter with switches is proposed. The system can utilize a half-bridge (HB) LC series resonant inverter for heating FM pots or a full-bridge (FB) LLLC resonant inverter for heating NFM pots. Compared to the LLC resonant circuit, the LLLC resonant circuit significantly reduces output impedance angle and switching losses, thereby improving system efficiency. In addition, an average pulse density modulation (APDM)-pulse frequency modulation (PFM) control strategy is proposed for heating NFM cookware. During heavy loads, an APDM control strategy is adopted for power regulation; while during light loads, the system switches from FB resonant inverter to HB resonant inverter, and the control strategy changes from APDM to PFM. This ensures that the load current remains continuous, allowing the system to operate efficiently across the entire power range. Finally, a 5.5-kW/10-kHz experimental prototype was developed. The topology, the parameter design method, and the control strategy were verified through this prototype.