Effects of using DC-side average current-mode control on a three-phase converter with an input filter and distorted supply

The use of DC-side current sensing and proportional plus integral average c urrent-mode control is analysed and shown to have several beneficial effect s when applied to a three-phase, step-down, AC-DC, unity-power-factor conve rter. Conventionally, a large DC-side inductor was used with the considered converter, in order to reduce the propagation of harmonic currents due to nonsinusoidal supply voltages that result in the input currents being non-s inusoidal. A single DC-side current sensor, when used with an EPROM sinusoi dal look-up table PWM modulation method, is shown to have a number of benef its including; reduction of the harmonic currents when a finite-value DC-si de inductor is used, hence giving near-sinusoidal input currents and dampin g of the DC-side LC filter. Two other benefits are mentioned. The current-c ontrol loop is designed and the often ignored effect of the input filter on system stability is discussed. Two SIMULINK(TM) simulation models are deve loped and compared with each other.