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US 4,286,222 AGranted
Timing waveform generator
AssigneeWestinghouse Electric Corp.
InventorWilliam R. Caputo
Life of this patent
Estimating the term…
Abstract
A timing waveform generator which provides substantially noise immune timing waveforms in response to a polyphase source voltage suitable for thyristors. Each timing waveform is phase shifted from a reference sine wave using a combination of filtering and hysteresis, to achieve the total desired phase shift angle. The timing waveforms are also logically related to determine improper phase sequence and/or a missing phase.
Claims11
A timing waveform generator, comprising:
- a source of alternating potential,
- transducer means providing a first sine wave signal synchronous with said source of alternating potential,
- and phase shift means providing timing waveform which lags said first sine wave by a predetermined angle,
- said phase shift means including filter means and hysteresis means, said filter means filtering said first sine wave signal to provide a second sine wave signal which lags the first sine wave signal by a first angle, with the filter means being selected such that the first angle is less than said predetermined angle, said hysteresis means generating said timing waveform in response to said second sine wave signal, with said hysteresis means having a predetermined threshold selected to delay the timing waveform by a second angle which is equal to the predetermined angle minus the first angle to cause the timing waveform to lag the first sine wave by said predetermined angle.
1 more element
A timing waveform generator, comprising:
- a three-phase source of alternating potential,
- means providing first, second, and third digital timing signals 120 electrical degrees apart in response to the three phases of said three-phase source, with said timing signals having a duration which exceeds 120 electrical degrees,
- phase monitoring means which logically relates a predetermined edge of each timing waveform with a predetermined one of the remaining timing waveforms, with said phase monitoring means providing a signal indicative of an improper relationship.
Dependencies are inferred from the claim text.