Adjusting gate pulse time intervals for reflected wave mitigation
AssigneeRockwell Automation Technologies, Inc.
InventorsJerry D. Thunes, Russel J. Kerkman, Takayoshi Matsuo
Life of this patent
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Abstract
Methods and apparatus for controlling switching in a DC-to-AC inverter to prevent overvoltages applied to an AC motor by determining the switching order of the phase voltage signals, providing gating signals at switching intervals by modulating a carrier wave with the phase voltage signals, comparing the switching intervals to a predetermined minimum time interval sufficient for reflected wave transients to dissipate, and adjusting the switching intervals to be at least equal to the predetermined minimum time interval.
Claims15
A method of controlling switching in a DC-to-AC inverter to prevent overvoltages applied to an AC motor by requiring a minimum time interval between gating signals that are produced in response to phase voltage signals, the method comprising:
- determining the switching order of the phase voltage signals;
- providing gating signals at switching intervals by modulating a carrier wave with the phase voltage signals;
- comparing the switching intervals to a predetermined minimum time interval sufficient for reflected wave transients to dissipate;
- and
- adjusting the switching intervals to be at least equal to the predetermined minimum time interval.
A controller for providing gating signals at time intervals to switches in a DC-to-AC inverter by modulating a carrier wave with phase voltage signals, the controller preventing overvoltages by requiring a time interval between gating signals, the controller having a CPU executing a control program having a first portion for determining a switching order of the phase voltage signals, the CPU executing a second portion of the control program for comparing the time intervals to a predetermined minimum time interval sufficient for reflected wave transients to dissipate, and the CPU executing a third portion of the control program for adjusting the time intervals between respective pairs of the gating signals to be at least equal to the predetermined minimum time interval.
Dependencies are inferred from the claim text.