An optimizer , comprising: a conversion unit , wherein an input end of the conversion unit is configured to be connected to at least one photovoltaic module , and perform power conversion on the connected photovoltaic module ; a control unit , configured to control the conversion unit ; and an auxiliary power source , an energy storage unit , and a first unidirectional conduction unit that are electrically connected between the conversion unit and the control unit , wherein the auxiliary power source is configured to provide a working voltage for the control unit , the energy storage unit is configured to provide electric energy for the auxiliary power source or the control unit , and the first unidirectional conduction unit is configured to prevent the electric energy of the energy storage unit from falling with a decrease of a voltage of the photovoltaic module , characterized in that the control unit is further configured to perform current-voltage IV curve scanning for voltage segments, wherein the voltage segments are obtained by segmenting a range of an output voltage of the photovoltaic module corresponding to the optimizer from an open-circuit voltage to a preset minimum voltage, and at least two voltage segments are obtained through division, wherein two endpoints of a first voltage segment of the voltage segments obtained through division are respectively the open-circuit voltage and a threshold voltage of the photovoltaic module , wherein the threshold voltage of the photovoltaic module is less than a minimum voltage needed by the auxiliary power source for working, and a range from the threshold voltage of the photovoltaic module to the preset minimum voltage is divided into at least two voltage segments. a conversion unit , wherein an input end of the conversion unit is configured to be connected to at least one photovoltaic module , and perform power conversion on the connected photovoltaic module ; a control unit , configured to control the conversion unit ; and an auxiliary power source , an energy storage unit , and a first unidirectional conduction unit that are electrically connected between the conversion unit and the control unit , wherein the auxiliary power source is configured to provide a working voltage for the control unit , the energy storage unit is configured to provide electric energy for the auxiliary power source or the control unit , and the first unidirectional conduction unit is configured to prevent the electric energy of the energy storage unit from falling with a decrease of a voltage of the photovoltaic module , characterized in that the control unit is further configured to perform current-voltage IV curve scanning for voltage segments, wherein the voltage segments are obtained by segmenting a range of an output voltage of the photovoltaic module corresponding to the optimizer from an open-circuit voltage to a preset minimum voltage, and at least two voltage segments are obtained through division, wherein two endpoints of a first voltage segment of the voltage segments obtained through division are respectively the open-circuit voltage and a threshold voltage of the photovoltaic module , wherein the threshold voltage of the photovoltaic module is less than a minimum voltage needed by the auxiliary power source for working, and a range from the threshold voltage of the photovoltaic module to the preset minimum voltage is divided into at least two voltage segments. <EOS>