Reduced-Parts Active Filters

Reducing the number of power electronic components in an active filter topology decreases the cost of the system. Active filters are the best tools for harmonic mitigation as well as reactive power compensation, load balancing, voltage regulation, and voltage flicker compensation. Unified power quality conditioners (UPQC), also known as universal active filters, are ideal devices for improving power quality. The chapter discusses different topologies of single-phase UPQC topologies. In an active filter system, for the controllability of the system, the voltage of the DC bus must be 32 times the peak voltage of the line. The main types of the static uninterruptible power supply (UPS) systems are on-line, off-line, and line-interactive configurations. The main advantages of off-line UPS topology are a simple design, low cost, and small size. Power flow through the rectifier and inverter during the normal operation means higher power losses and lower efficiency compared to offline and line-interactive UPS systems.