Three-phase rectifier with near-sinusoidal input currents and capacitors parallel connected with the upper diodes

In order to improve the distorted current of the conventional uncontrolled rectifier connected with the capacitance load, former researchers used to propose a new rectifier where inductors are series connect with the ac side and capacitors are parallel connected with the upper diodes. Although improved input current is achieved, the rectifier uses LC filter in the dc side, resulting in large size of the equipment. Moreover, no valid design method is proposed, limiting the application of the rectifier. This paper proposes a novel three-phase rectifier with near-sinusoidal input currents, which is composed of ac-side inductors, three-phase uncontrolled rectifier, commutation capacitor parallel connected with the upper diode and the dc-side filter capacitor. The operation principle of this novel rectifier is analyzed, and the differences of the characteristics between two rectifiers are compared. Additionally, practical parameter optimal design methods of the two rectifiers are proposed. Experimental results show that good harmonic rejection is obtained by using the two rectifiers. Compared with the rectifier with dc-side LC filter, the novel rectifier with dc-side C filter has better comprehensive performance.