Abstract: A power detection circuit is provided for detecting current total input power of a resonant circuit. The power detection circuit includes a detection circuit and an estimation circuit. The detection circuit receives a current signal and obtains resonant-slot baseband power according to the current signal to generate the baseband power value. The current signal represents a resonant-slot current generated by the resonant circuit. The estimation circuit receives the baseband power value and estimates the current total input power according to the baseband power value to generate an estimated power value.

Abstract: A heating device includes a resonant circuit, a detection unit and a control unit. The resonant circuit includes an inverter circuit and a resonant tank. The inverter circuit provides a resonant tank current and a resonant tank voltage. The resonant tank includes a heating coil, a resonant tank capacitor, a resonant tank equivalent inductor and a resonant tank equivalent impedance. The detection unit detects the resonant tank current and the resonant tank voltage to acquire associated parameters. The detection unit calculates an inductance of the resonant tank equivalent inductor according to a capacitance of the resonant tank capacitor, a resonant period and a first expression. The detection unit calculates an impedance value of the resonant tank equivalent impedance according to the inductance of the resonant tank equivalent inductor, a time difference, the resonant period, a reference current value, a negative peak current value and a second expression.

Abstract: A power detection circuit is provided for detecting current total input power of a resonant circuit. The power detection circuit includes a detection circuit and an estimation circuit. The detection circuit receives a current signal and obtains resonant-slot baseband power according to the current signal to generate the baseband power value. The current signal represents a resonant-slot current generated by the resonant circuit. The estimation circuit receives the baseband power value and estimates the current total input power according to the baseband power value to generate an estimated power value.