Terminator for reducing differential-mode and common-mode voltage reflections in ac motor drives
AssigneeRockwell Automation Technologies, Inc.
InventorsRangarajan M. Tallam, Gary L. Skibinski
Life of this patent
Estimating the term…
Abstract
A terminator reduces reflections on power lines connecting an inverter to an AC motor by providing a differential-mode reflection damping element and at least one common-mode reflection damping element, the latter including a series capacitance to substantially reduce power dissipation in the resistance of the damping elements.
Claims9
A terminator for reducing electrical transients on a power cable having three conductors to provide three-phase power to an AC motor from a solid-state motor drive, the terminator comprising:
- three differential-mode damping elements each having a series connected resistive and capacitive component, the differential-mode damping elements connected to each of the three conductors to provide equal impedances from each conductor to the other conductors;
- at least one common-mode damping element having a series connected resistive and capacitive component, the common-mode damping element providing a path from each conductor to ground;
- wherein the differential-mode damping elements provide impedance between each of the conductors substantially equal to a differential-mode characteristic impedance of the power cable and
- wherein the common-mode damping element provides an impedance between each of the conductors and ground substantially equal to a common-mode characteristic impedance of the power cable.
A method for reducing electrical transients on a power cable having three conductors providing power to an AC motor driven by a solid-state motor drive, the method comprising the steps of:
- (a) connecting three differential-mode damping elements each having a series connected resistive and capacitive component between each of the three conductors to provide equal impedances from each conductor to the other conductors;
- (b) providing a path from each conductor to ground through at least one common-mode damping element having a series connected resistive and capacitive component;
- wherein the differential-mode damping elements provide impedance between each of the conductors substantially equal to a differential-mode characteristic impedance of the power cable and
- wherein the common-mode damping element provides an impedance between each of the conductors and ground substantially equal to a common-mode characteristic impedance of the power cable.
Dependencies are inferred from the claim text.