Current Sensorless Online Load Estimation for Induction Heating Cooker

This paper proposes a current sensorless online load estimation method for induction heating cooker (IHC) to detect the cookware status, such as cookware material or position. First, the operating principle of half-bridge series converter (HBSRC) is analyzed, and then using the signals during natural resonant period to estimate cookware equivalent electrical parameters. Furthermore, to derive the equations of equivalent inductance and resistance based on resonant capacitor voltage, and verify the proposed method in simulation software. This method only needs to sample the key signals of resonant capacitor voltage to reduce the calculation loading and time in software. Finally, a DSP-based HBSRC is built to verify the proposed current sensorless load estimation method. The effectiveness of the proposed method is verified by experimental results with different cookware material and equivalent heating coverage ratio (EHCR). The maximum error of estimated inductance and resistance are 8.4% and 9.1%, respectively, indicating that the proposed estimation method is effective and can distinguish whether to execute heating power control.