Modular Three-Phase Diode Rectifier With High-Frequency Isolation and Selective Harmonic Elimination Modulation

This article proposes a modular three-phase diode rectifier with high frequency isolation and selective harmonic elimination in input currents. The proposed system consists of modular ac–ac converters with 20 kHz transformer isolation on the primary side followed by a three-phase diode rectifier to produce a high quality dc output voltage. A new hybrid pulsewidth modulation scheme is proposed that combines the high frequency 20 kHz transformer operating frequency with a low frequency selective elimination of 5th, 7th, 11th, and 13th current harmonics in the 60 Hz input currents resulting in near sinusoidal waveform.Therefore, high quality input current is achieved in open loop. The secondary side consists of a three-phase diode rectifier with high quality output, suitable for ev-charging/switch mode power supplied in data centers etc. The output dc voltage is shown to be regulated via a simple duty cycle control of the high frequency (20 kHz) without affecting the harmonic elimination features in the input currents. The proposed approach is modular and can adapt to higher input voltages. Simulation results are discussed, which explore all the features of the proposed high performance ac to dc rectifier. Select results are verified experimentally on a 120 V rms line-to-line, three-phase, 1 kW laboratory prototype system.¹¹

This article is the updated version of [1] and include more details about the output DC voltage regulation, the design of input (AC) and output (DC) filter, additional experimental results among other changes