An inverter, comprising an inverter circuit (220, 430), an inverter controller and a circuit for modulating a control signal, wherein the circuit for modulating a control signal is connected to the inverter controller of the inverter and comprises: a DC/DC boost circuit (120, 310, 320, 420); and a control unit, wherein the DC/DC boost circuit (120, 310, 320, 420) comprises a first capacitor, a first inductor, a first controllable switch, a second capacitor, and a controllable switch circuit, wherein the first capacitor is connected in parallel with an input end of the DC/DC boost circuit (120, 310, 320, 420), and said input end is configured to be connected to a photovoltaic string, PV,; the second capacitor is connected in parallel with an output end of the DC/DC boost circuit (120, 310, 320, 420), and said output end is connected to a direct current end of the inverter circuit (220, 430); a terminal of the first inductor is connected to a positive input port of the DC/DC boost circuit (120, 310, 320, 420), and another terminal of the first inductor is connected to a positive output port of the DC/DC boost circuit (120, 310, 320, 420) via the controllable switch circuit; a terminal of the first controllable switch is connected to a common terminal of the first inductor and the controllable switch circuit, and another terminal of the first controllable switch is connected to a negative input port; wherein the inverter controller is configured to acquire a control signal generation instruction, and to transmit the control signal generation instruction to the control unit of the circuit for modulating a control signal; wherein the control unit is configured to control, upon receiving a control signal generation instruction from the inverter controller and when a voltage of the first capacitor is greater than or equal to a first voltage threshold, at least one of a duty cycle of a signal for controlling the first controllable switch and a frequency for controlling the first controllable switch, to control the first capacitor to discharge when the first controllable switch is switched on or stop discharging when the first controllable switch is switched off, to generate a control signal with a predetermined characteristic waveform at the first capacitor according to the control signal generation instruction, wherein the control signal is to be analyzed by a control module in a photovoltaic string, PV, connected to the inverter, to obtain a control instruction to be executed by the control module. a DC/DC boost circuit (120, 310, 320, 420); and a control unit, wherein the DC/DC boost circuit (120, 310, 320, 420) comprises a first capacitor, a first inductor, a first controllable switch, a second capacitor, and a controllable switch circuit, wherein the first capacitor is connected in parallel with an input end of the DC/DC boost circuit (120, 310, 320, 420), and said input end is configured to be connected to a photovoltaic string, PV,; the second capacitor is connected in parallel with an output end of the DC/DC boost circuit (120, 310, 320, 420), and said output end is connected to a direct current end of the inverter circuit (220, 430); a terminal of the first inductor is connected to a positive input port of the DC/DC boost circuit (120, 310, 320, 420), and another terminal of the first inductor is connected to a positive output port of the DC/DC boost circuit (120, 310, 320, 420) via the controllable switch circuit; a terminal of the first controllable switch is connected to a common terminal of the first inductor and the controllable switch circuit, and another terminal of the first controllable switch is connected to a negative input port; wherein the inverter controller is configured to acquire a control signal generation instruction, and to transmit the control signal generation instruction to the control unit of the circuit for modulating a control signal; wherein the control unit is configured to control, upon receiving a control signal generation instruction from the inverter controller and when a voltage of the first capacitor is greater than or equal to a first voltage threshold, at least one of a duty cycle of a signal for controlling the first controllable switch and a frequency for controlling the first controllable switch, to control the first capacitor to discharge when the first controllable switch is switched on or stop discharging when the first controllable switch is switched off, to generate a control signal with a predetermined characteristic waveform at the first capacitor according to the control signal generation instruction, wherein the control signal is to be analyzed by a control module in a photovoltaic string, PV, connected to the inverter, to obtain a control instruction to be executed by the control module.