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US 4,048,520 AGranted
Three-phase SCR drive circuit using an opto-coupled pulse amplifier
AssigneeVectrol, Inc.
InventorsNicholas G. Muskovac, Bruce I. Formhals
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Abstract
A three-phase shift network includes a single transistor which controls phase shift by introducing a variable resistance into the network as determined by a D.C. control signal supplied to the transistor. The three-phase signals generated from the phase shift network undergo pulse shaping and are subsequently introduced into an opto-coupled pulse amplifier. The amplifier drives large SCR devices, connected as a load.
Claims6
An SCR drive circuit comprising:
- a plurality of means for selectively shifting each phase of multiple phase electrical signals;
- respective means each having an output and connected in circuit with an output of each phase shifting means for shaping each of the phase shifted signals;
- and
- respective opto-coupled means connected in circuit with an output of a respective shaping means for generating trigger signals for firing SCR devices connected as loads to respective opto-coupled means;
- respective means connected between an input of each phase shifting means and power lines for isolating the respective phase shifting means from direct connection to the power lines.
2 more elements
A phase shifting network for multiple phase operation comprising:
- a plurality of rectifier diode bridges, each bridge having:
- first and second terminals connected to a source of A.C. power;
- third and fourth terminals respectively connected to an emitter and a collector of a common transistor;
- means for introducing a variable D.C. bias to a base of the transistor for varying the resistivity imposed by the transistor on all of the bridges;
- and
- connecting means connected to the second terminal and a preselected potential point of the power source for making available thereat a signal that is phase shifted relative to the remaining diode bridges.
3 more elements
Dependencies are inferred from the claim text.