Device and method for suppressing harmonic distortions at the output of variable frequency drive
OwnerDmytro Khachaturovinventor
Life of this patent
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Abstract
A device for suppressing harmonic distortions at the output of variable frequency drive (VFD) comprising at least one passive harmonic filter (PHF) which has a set of storage elements and a set of inductive elements. The set of inductive elements are mounted on a magnetic core. The PHF comprising at least two lines connected in parallel (parallel lines) with similar sets of elements. The described technical solution expands the possibility of operating the VFD/VSD with different supply voltage frequencies, and maintains the THD/TDD values within 5% regardless of active power fluctuations.
Claims9
A device for suppressing harmonic distortions at the output of a variable frequency drive (1) (VFD) is designed as a passive harmonic filter (PHF) comprising:
- at least two lines (10;
- 11) connected in parallel (parallel lines),
- a storage elements set (4) and an inductive elements set (7) for each of parallel lines (10;
- 11),
- wherein the inductive elements set (7) are mounted on a magnetic structure,
- wherein the inductive elements set (7) of the PHF comprising at least a first (7.1) and a second (7.2) sets of the inductive elements mounted on separate cores (6) and connected through an input,
- wherein the first set (7.1) is connected to a first parallel line (10) and the second set (7.2) is connected to a second parallel line (11), and
- the (7) inductive elements set (7) is installed in a separate compartment (8) of the VFD,
- wherein the inductive elements set (7) is cooled via forced air cooling;
- wherein each of the parallel lines (10;
- 11) is connected in series with separate adjustable rectifiers (13;
- 12) of the VFD (1);
- wherein the storage elements set (4) of each parallel line comprising a first (4.1) and a second (4.2) capacitor sets equipped with adjustable contactors (17.1;
- 17.2),
- wherein at least a part of each storage elements set (4) is active;
- wherein a capacity of the storage elements set (4) of each parallel line (10;
- 11) is changeable depending on a supply voltage frequency.
A method for suppressing harmonic distortions at the output of a variable frequency drive comprising:
- installing a passive harmonic filter (PHF) within the variable frequency drive (VFD) housing (2);
- forming the passive harmonic filter (PHF) with:
- at least two lines (10;
- 11) connected in parallel (parallel lines),
- wherein each of the parallel lines is connected in series with a separate adjustable rectifier (12;
- 13) of the VFD,
- a storage elements set (4) with a first (4.1) and a second (4.2) capacitor sets equipped with adjustable contactors (17.1;
- 17.2), and
- an inductive elements set (7) with a first (7.1) and a second (7.2) inductive elements sets,
- wherein the first set (7.1) is connected to a first parallel line (10) and the second set (7.2) is connected to a second parallel line (11),
- wherein the inductive elements sets (7.1;
- 7.2) are mounted on at least two separate magnetic cores (6);
- providing a number of operating modes of said PHF,
- wherein a first operating mode is a half power mode (HPM) and a second operating mode is a full power mode (FPM);
- providing the first operating mode, when an active power current is reduced more than 50% of a nominal value,
- wherein the first operating mode comprising:
- disconnecting one of at least two parallel lines (10) or (11) of the PHF via switching off the related adjustable rectifier (13) or (12) of the VFD, and
- opening an adjustable contactor (17.1) of the storage elements set (4) of one of the disconnected line (10) or (11) of the PHF;
- configuring the PHF to change the operating mode between at least two operating modes depending on the measured active power current and a supply voltage frequency value;
- providing a step-disconnection/connection of the adjustable contactors (17.1;
- 17.2) of the capacitor sets (4.1, 4.2) during changing the operating modes.
Dependencies are inferred from the claim text.