Patent ID: 8339112

Claim:
A method of analog maximum power point tracking in a photovoltaic power generation device including a DC-DC converter for an output voltage of at least one panel controlled by a pulse width modulated (PWM) drive signal of a variable duty-cycle generated by a PWM control circuit, the method comprising: detecting whether the DC-DC converter is in one of a discontinuous conduction mode (DCM) and a continuous conduction mode (CCM), the photovoltaic power generation device switching between the DCM and the CCM based upon a load condition of the DC-DC converter; analog multiplying of a current voltage at panel terminals by a time ratio of a current duty-cycle of the PWM drive signal for producing a first analog product signal corresponding to a current power output from the at least one panel when the DC-DC converter is in DCM; analog multiplying of a magnitude signal representing a voltage drop of the DC-DC converter during conduction phases by a voltage gain factor and low pass filtering a result signal for producing a second analog product signal corresponding to a current power output to an electrical load of the DC-DC converter when in CCM; comparing a first input signal, the first input signal being selected from one of the first and second analog product signals as representing an actual current power output from the at least one panel, with a second input signal, the second input signal comprising one of a delayed replica of the first input signal and a time averaged value of the first input signal, the comparing for determining when the second input signal becomes greater than the first input signal and for outputting a flag signal thereupon; and inverting a sign of variation of the duty-cycle of the PWM drive signal when the second input signal becomes greater than the first input signal.