NOVELTY - The method involves receiving (S201) sinusoidal signals. A maximum value, median value and minimum value of sinusoidal signals are obtained (S202) to generate first difference between maximum and minimum value. A second difference is generated (S203) according to upper limit and a lower limit of predetermined comparison value. The first difference is compared (S204) with second difference to generate an optimized modulation signal. The maximum value in negative is added (S206) to minimum value in negative to generate sum, when first difference is smaller than second difference.    USE - Modulation method of control device (claimed) for eliminating surge current in electronic apparatus such as electric automobile, solar power conversion system and direct current/alternating current (DC/AC) converter for use in domestic associated controller industry.    ADVANTAGE - The surge signals can be greatly improved and maximum input value can be achieved by the control signals to allow the load to fully exercise maximum performance. Therefore the smooth signal waveform can be obtained and prolong lifecycle can be ensured. The specifications of the power stage can be directly integrated to an existing controller without changing a volume of a controller. The compactness can be achieved at the same time and added values of the load and the controller can be enhanced. The need for additional detection device or changes to hardware specifications of the controller can be avoided and therefore the costs of power elements of the controller can be reduced and the operation performance of the load at the same time can be enhanced. The original specifications and functions of the controller can be preserved.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for control device supporting modulation method.    DESCRIPTION OF DRAWING(S) - The drawing shows a flowchart illustrating the modulation method for eliminating a current surge.    Step for receiving sinusoidal signals (S201)    Step for obtaining maximum value, median value and minimum value of sinusoidal signals to generate first difference between maximum and minimum value (S202)    Step for generating second difference according to upper limit and a lower limit of predetermined comparison value (S203)    Step for comparing first difference with second difference to generate an optimized modulation signal (S204)    Step for adding maximum value in negative is to minimum value in negative to generate sum, when first difference is smaller than second difference (S206)