Electricity: motive power systems – Induction motor systems – Primary circuit control
Patent
1990-05-25
1992-04-07
Shoop, Jr., William M.
Electricity: motive power systems
Induction motor systems
Primary circuit control
361 33, H02P 100
Patent
active
051031540
ABSTRACT:
A single phase, capacitor start electric motor is shown in which energization of the auxiliary winding is controlled by a triac. The triac is protected from excessive voltages caused by the vector sum of capacitor, line and induced voltages which can occur at turn-off of the triac. The triac is protected in several embodiments by a gated semiconductor switch serially connected to a current limiting or discharge resistor, both being coupled across the triac. The semiconductor switch has a voltage breakdown device connected in its gate circuit. When voltage across the triac exceeds a selected level the gated semiconductor is turned on thereby drawing sufficient current momentarily to limit the voltage across the triac to a safe level and allowing the capacitor to discharge its voltage through the auxiliary winding circuit. In another embodiment a stack of high voltage bilateral triggering devices is placed across the triac.
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Dropps Kevin J.
Thompson Herbert A.
Baumann Russell E.
Donaldson Richard L.
Grossman Rene E.
Shoop Jr. William M.
Texas Instruments Incorporated
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