Drive output harmonic mitigation devices and methods of use thereof
View Patent ↗A filter for filtering a three-phase electrical power waveform produces a three-phase output power waveform. The filter has an inductor with three sets of first and second coils, each having a capacitor connected in series therewith. Each of the three sets of first and second coils has a tap intermediate the first and second coils where the output waveform is present, each tap capable of being connected to a load. In some embodiments, the inductor is passive adaptive and includes resistors for reducing current in-rush.
1. A device for modifying an input electrical waveform generated by a source of electrical power provided on a first conductor, comprising:
a first inductor capable of connecting to the first conductor;
a second inductor connected in series to the first inductor distal to the first conductor;
a capacitor connected in series with the second inductor distal to the first inductor;
a second conductor connected between the first inductor and the second inductor, the second conductor capable of presenting an output waveform;
wherein at least one of the first and second inductors is an adaptive passive inductor.
2. The device of claim 1 , wherein a relative polarity between the first inductor and the second inductor is additive.
3. The device claim 2 , wherein the input electrical waveform is a first electrical waveform and wherein the source of electrical power produces a plurality of electrical waveforms, each provided on one of a plurality of conductors and further comprising a plurality of devices, each having a first inductor capable of connecting to one of the plurality of conductors, a second inductor connected in series to the first inductor, a capacitor connected in series with the second inductor distal to the first inductor and a plurality of second conductors connected between the first inductor and the second inductor, the plurality of second conductors capable of presenting a multi-phase output waveform.
4. The device of claim 3 , wherein the plurality of electrical waveforms is three in number, each having a different phase to provide three-phase electrical power at three second conductors.
5. The device of claim 2 , wherein the first inductor and the second inductor are disposed on a common core.
6. The device of claim 4 , wherein each of the series connected first inductors and second inductors are disposed on a common core.
7. The device of claim 1 , wherein the source of electrical power is an adjustable speed drive.
8. The device of claim 4 , wherein the output waveform is supplied to an electric motor.
9. The device of claim 1 , wherein the device reduces harmonic currents being present in the second inductor.
10. The device of claim 1 , further comprising a resistor interposed between and in series with the second inductor and the capacitor.
11. The device of claim 1 , wherein each of the first and second inductors is an adaptive passive inductor.
12. The device of claim 11 , further comprising an E-shaped core each of the first and second inductors being wound about a corresponding leg of the E-shaped core and further comprising an I-shaped core disposed proximate to ends of each leg of the E-shaped core and further comprising a high permeability core gap piece disposed between each leg of the E-shaped core and the I-shaped core.
13. A filter for filtering an input electrical power waveform to produce an output power waveform, comprising:
an inductor having first and second coils,
a capacitor connected in series,
tap terminal intermediate first and second inductors,
a conductor, extending from the tap terminal and being capable of being connected to a load;
wherein the input electrical power is provided by an adjustable speed drive and the load is a motor; and
wherein the inductor is an adaptive passive inductor and comprising a resistor connected in series between the inductor and the capacitor.
14. The filter of claim 13 , wherein the input electrical power is provided by an adjustable speed drive and the load is a motor.
15. A filter for filtering a three-phase electrical power waveform to produce a three-phase output power waveform, comprising:
an inductor, having three sets of first and second coils, each set of coils having a capacitor connected in series therewith, each of the capacitors is connected in common distal to a respective series connection with a respective second coil, each of the three sets of first and second coils having respective tap intermediate first and second coils where the output waveform is present, each tap intermediate coil being capable of being connected to a load;
wherein the inductor is passive adaptive inductor and further comprising a resistor connected in series between the inductor and the capacitor, the load being a three-phase electric motor; and
wherein the inductor is formed on an E-shaped core, each of the three sets of first and second coils being wound on a corresponding leg of the E-shaped core.
16. The device of claim 1 , further comprising a three phase core, each of the first and second inductors being wound about a corresponding portion of the three phase core.