25-08-2017, 09:32 PM
A Hybrid Active Filter
A Hybrid Active Filter.doc (Size: 159.5 KB / Downloads: 36)
EXISTING SYSTEM:
Standard AC supply is converted to a DC voltage by using a 3-phase diode bridge rectifier. A capacitor filters the ripple in the DC bus. This DC bus is used to generate a variable voltage and variable frequency power supply. A voltage source power inverter is used to convert the DC bus to the required AC voltage and frequency. In summary, the power section consists of a power rectifier, filter capacitor, and power inverter.
The main 3-phase supply is rectified by using the 3-phase diode bridge rectifier. The DC ripple is filtered by using an electrolytic capacitor. This DC bus is connected to the IGBTs for inverting.
DRAW BACKS:
The diode rectifier produces a large amount of harmonic current at the line side, and therefore, it does not comply with harmonic guidelines or regulations.
ADVANTAGES:
A hybrid active filter for mitigating the line-side harmonic currents is proposed. For a three-phase 12-pulse diode rectifier. This hybrid filter consists of series connection of a simple LC filter tuned to the 11th-harmonic frequency with a small-rated active filter using a three-level neutral-point clamped NPC PWM converter. The hybrid active filter has the following advantages over a pure active filter and a traditional passive filter consisting of multiple-tuned LC filters and a high pass filter: the active filter taking part in the hybrid filter is much smaller in converter capacity than the pure active filter. The simple single-tuned LC filter used in the hybrid filter is much smaller in size, lower in cost and weight, than the traditional passive filter.