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US 7,405,498 B2Granted
Multi-level active filter
AssigneeSiemens Energy & Automation, Inc.
InventorsMukul Rastogi, Peter Hammond, Stan Simms
Life of this patent
Estimating the term…
Abstract
A multi-phase active filter includes a group of power cells electrically connected in a three-phase configuration, a precharging circuit, and a controller that controls the voltage delivered to the plurality of power cells. Each power cell includes an inverter having a pair of direct current (DC) terminals, at least one capacitor electrically connected in parallel with the inverter, and an energy dissipating circuit that is electrically connected in parallel with the inverter. The energy dissipating circuit of each power cell self-regulates DC voltage within the cell.
Claims20
A multi-phase active filter, comprising:
- a plurality of phases, each phase comprising a plurality of power cells electrically connected in series;
- wherein each phase has a first end and a second end, the first ends of each phase are electrically coupled to each other, and the second ends of each phase are positioned to be electrically connected between a power source and a load at a point of common coupling;
- wherein each power cell comprises:
- an inverter having a pair of direct current (DC) terminals,
- a filter device that is electrically connected across the DC terminals of the inverter, and
- an energy dissipating circuit that is electrically connected across the DC terminals of the inverter.
3 more elements
A multi-phase active filter, comprising:
- a plurality of phases, each phase comprising a plurality of power cells electrically connected in series;
- and
- a central controller;
- wherein each phase has a first end and a second end, the first ends of each phase are electrically coupled to each other, and the second ends of each phase are positioned to be electrically connected between a power source and a load at a point of common coupling;
- wherein each power cell comprises an inverter having a pair of DC terminals, a rectifier electrically connected across the DC terminals, and a capacitor that is electrically connected across the DC terminals;
- wherein each rectifier receives power from a set of dedicated three-phase secondary windings of a transformer;
- and
- wherein the central controller comprises:
- a device that scales and filters signals from the point of common coupling, and
- a regulator that receives the filtered signals and provides an output to one or more pulse width modulation comparators.
7 more elements
A multi-phase active filter, comprising:
- a plurality of power cells electrically connected in a three-phase configuration;
- a precharging circuit;
- and
- a controller that controls the voltage delivered to the plurality of power cells;
- wherein each power cell comprises an inverter having a pair of direct current (DC) terminals, at least one capacitor electrically connected in parallel with the inverter, and an energy dissipating circuit that is electrically connected in parallel with the inverter;
- wherein the energy dissipating circuit of each power cell self-regulates DC voltage within the cell;
- and
- wherein the precharging circuit comprises:
- a first contactor a first inductor and a second inductor electrically connected in series such that the first contactor is between the first inductor and the second inductor;
- and
- a second contactor electrically connected in parallel across the first contactor and first inductor;
- wherein the first contactor closes to energize the power cells the second contactor closes when the power cells have charged to a nominal DC voltage, and the first contactor opens after the second contactor has closed.
9 more elements
A multi-phase active filter, comprising:
- a plurality of phases, each phase comprising a plurality of power cells electrically connected in series;
- and
- a precharging circuit;
- wherein each phase has a first end and a second end, the first ends of each phase are electrically coupled to each other, and the second ends of each phase are positioned to be electrically connected between a power source and a load at a point of common coupling;
- wherein each power cell comprises an inverter having a pair of direct current (DC) terminals and an energy dissipating circuit that is electrically connected across the DC terminals of the inverter;
- wherein the precharging circuit comprises:
- a first contactor, a first inductor, and a second inductor electrically connected in series such that the first contactor is between the first inductor and the second inductor, and
- a second contactor electrically connected in parallel across the first contactor and first inductor;
- and
- wherein the first contactor closes to energize the power cells, the second contactor closes when the power cells have charged to a nominal DC voltage, and the first contactor opens after the second contactor has closed.
7 more elements
Dependencies are inferred from the claim text.