Active harmonic suppression of paralleled 12-pulse rectifier at DC side

In order to improve the ability of harmonic suppression, and reduce the loss of switching devices, this paper proposes an active harmonic suppression method at dc side of multi-pulse rectifier (MPR). The circulating current through secondary winding of active inter-phase reactor (AIPR) is derived from the current relation between the ac and dc sides of MPR when the three-phase input currents are sinusoidal simultaneously, and an applicable circulating current is presented. According to the relation between voltage across secondary winding of AIPR and the applicable current, it is confirmed that harmonic energy of input line current can be consumed by the resistor in series with the secondary winding. A half-bridge PWM rectifier is designed to abstract the harmonic power and to feed the load, which can realize the recycling of harmonic energy. Experimental results show that the power factor of the proposed system is approximately equal to one when the PWM rectifier operates normally, and that the proposed system has the ability of anti-variation of load and input voltage.