專利摘要：
A control method for reducing second-order ripple is adapted to reduce second-order ripple on an input side of a DC-DC conversion device, wherein the input side of the DC-DC conversion device is coupled to a preceding voltage supply device, and an output side of the DC-DC conversion device is coupled to a DC-AC transforming device, characterized in that a voltage control device for controlling the preceding voltage supply device is designed according to a transfer function, and the transfer function is adjusted and controlled with an output voltage of the DC-DC conversion device and an amplitude voltage of pulse width modulation to reduce second-order ripple of an input voltage input to the input side of the DC-DC conversion device, thereby dispensing the need to increase circuits or increase capacitance of components and cutting costs.