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US 4,490,780 AGranted
Digital power converter
AssigneeAllen-Bradley Company, Inc.
InventorThomas A. Nondahl
Life of this patent
Estimating the term…
Abstract
A microprocessor-based static converter control circuit includes a free-running counter which is synchronized with the powerline phase and frequency using a zero-crossing detector circuit. Firing angle commands are received and converted to a corresponding firing count. The microprocessor outputs a firing code for the thyristor firing pulse circuit when the count of the free running counter reaches the firing count.
Claims5
A control circuit for a static converter, the combination comprising:
- a firing pulse circuit for firing thyristors in response to a received firing code;
- a zero crossing detector for generating a signal which is synchronized with the line voltage applied to the thyristors;
- a free running counter which generates a binary count that is continuously changed;
- synchronizing means coupled to the zero crossing detector and the free running counter for periodically generating a reference count which indicates the binary count generated by the free running counter at a preselected phase of the line voltage;
- input means coupled to receive the reference count from the synchronizing means and summing it with a firing angle command to produce a firing count;
- and
- comparator means coupled to the input means and the free running counter for generating a firing code to the firing pulse ciruit when the binary count generated by the free running counter reaches a value which corresponds to the firing count.
4 more elements
Dependencies are inferred from the claim text.