Voltage sag and over-voltage compensation device with pulse-width modulated transformer

A device for selectively receiving electric power from an AC power source oscillating at a system frequency, adjusting the voltage of the power, and delivering a corresponding voltage-corrected AC power supply to a connected load;

• comprising:
• a transformer;
• a cascade of series connected full-bridge rectifier circuits connected between the AC power source and the center pole;
• a plurality of switching devices, each located within a corresponding full-bridge rectifier circuit, for selectively connecting the AC power source between the neutral and center poles when the switching devices are gated to a closed configuration, and for selectively disconnecting the AC power source from connection between the neutral and center poles when the switching devices are gated to an open configuration;
• and
• a control unit for selectively gating the switching devices a between the open configuration and the closed configuration multiple times per cycle of the system frequency to generate the voltage-corrected AC power supply for delivery to the load.

A device for selectively receiving electric power from an AC power source oscillating at a system frequency, adjusting the voltage of the power, and delivering a corresponding voltage-corrected AC power supply to a connected load;

• comprising:
• a transformer having:
• a first winding around a flux linking core and connected between a neutral pole and a center pole;
• a second winding around the flux linking core and connected between a center pole and an upper pole;
• a cascade of series connected full-bridge rectifier circuits connected between the AC power source and the center pole;
• a plurality of switching devices, each located within a corresponding full-bridge rectifier circuit, for selectively connecting the AC power source between the neutral and center poles when the switching devices are gated to a closed configuration, and for selectively disconnecting the AC power source from connection between the neutral and center poles when the switching devices are gated to an open configuration;
• a plurality of snubber circuits, each connected in parallel with a corresponding switching device, and each switching device and each corresponding snubber circuit located within a corresponding full-bridge rectifier circuit connected between the AC power source and the center pole;
• a plurality of upper-pole switching devices, each located within a corresponding full-bridge rectifier circuit, for selectively connecting the AC power source between the neutral and upper poles when the upper-pole switching devices are gated to a closed configuration, and for selectively disconnecting the AC power source from connection between the neutral and upper poles when the upper-pole switching devices are gated to an open configuration;
• a plurality of upper-pole snubber circuits, each connected in parallel with a corresponding upper-pole switching device, and each upper-pole switching device and each corresponding upper-pole snubber circuit located within a corresponding full-bridge rectifier circuit connected between the AC power source and the upper pole;
• a capacitor connected between the neutral and upper poles and configured to smooth the voltage-corrected AC power supply toward a sinusoidal power supply at the system frequency;
• a control unit for selectively gating the switching devices a between the open configuration and the closed configuration at a gating frequency that is substantially higher than the system frequency to generate the voltage-corrected AC power supply for delivery to the load;
• and
• a notch filter connected between the neutral and upper poles and configured to reduce power disturbances occurring in the voltage-corrected AC power supply in a filter frequency range comprising the gating frequency.