T-filter for reducing disturbances generated on a power grid by an active filter

An active filter arrangement for a power supply grid having a plurality of phases comprising:

• active filter circuitry connected in parallel between the power grid and a load connected to the power grid, the active filter circuitry comprising a plurality of filter bridges and a DC-link with each one of the filter bridges connected between each one of the plurality of phases of the power supply grid and the DC-link;
• passive filter circuitry that filters the active filter circuitry that is connected in series between the active filter circuitry and the power supply grid and load, the passive filter circuitry comprising a passive filter for each one of the plurality of phases that has a capacitor connected between a pair of series-connected inductors and to the capacitor of every other passive filter of every other one of the plurality of phases in a T-connection;
• and
• an active filter controller.

An active filter arrangement for a power supply grid having a plurality of phases comprising:

• active filter circuitry connected in parallel between the power grid and a load connected to the power grid, the active filter circuitry comprising a plurality of transistor bridges that each has a transistor and a DC-link with each one of the transistor bridges connected between each one of the plurality of phases of the power supply grid and the DC-link;
• filter circuitry that compensates for electrical power disturbances generated during switching of transistor bridges of the active filter circuitry, the filter circuitry connected in series between the active filter circuitry and the power supply grid and load, the filter circuitry comprising an LCL filter for each one of the plurality of phases with each LCL filter connected in series between one of the transistor bridges of the active filtering circuitry and a corresponding one of the power supply grid phases, and wherein each LCL filter includes a plurality of inductors connected in series and a capacitor connected thereto in between the series-connected inductors and connected to every other capacity of every other LCL filter in a T-connection;
• and
• a filter controller that controls transistor bridge switching.