Abstract: It is established by the voltage source converter supraharmonic model based on the principle of RC-SPWM. The relationship among the carrier randomness and amplitude as well as the phase randomness of supraharmonic is explored. The supraharmonic spectrum is distributed over a wider frequency range, and the amplitude of each supraharmonic approximates a normal distribution feature. The phases of supraharmonic approximate a uniform distribution feature due to the randomness of the carrier wave. The mechanism for supraharmonic elimination for converter clusters without carrier synchronization based on RC-SPWM is proposed, where the purpose of suppressing supraharmonic in a wide frequency range can be achieved. The simulation and experimental results demonstrate the effectiveness of the proposed supraharmonic elimination mechanism.