Force commutation static frequency changer apparatus using direct current chopper technique
First Claim
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1. An AC to AC static frequency changer apparatus for developing an AC output voltage across a load, comprising in combination, an AC polyphase input power source, a plurality of unilateral main switches cyclically and temporarily controlled for conduction under associated phases of said input power source;
- a DC voltage source, DC chopper means coupled between said DC voltage source and said plurality of main switches, said DC chopper means including cyclically controlled unilateral auxiliary switching means for applying a reverse voltage represented by the difference between said DC voltage and the line to neutral input voltage to said main switches, said reverse voltage being larger than the incoming line voltage for any conducting one of said main switches and with said auxiliary switching means being controlled for conduction at an instant subsequent to conduction of one of said main switches to apply said reverse voltage thereto and to establish a temporary path for the load current in derivation to said conductive one of said main switches, thereby to commutate conduction from said one main switch to the next main switch being controlled for conduction.
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Abstract
An improved force commutated cycloconverter is provided by selectively switching a DC chopper to different groups of main thyristors including a thyristor to be commutated in the controlled sequence of thyristor commutations. The DC chopper is self-commutating. The forced commutating circuit is applied to various configurations of cycloconverters.
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Citations
28 Claims
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1. An AC to AC static frequency changer apparatus for developing an AC output voltage across a load, comprising in combination, an AC polyphase input power source, a plurality of unilateral main switches cyclically and temporarily controlled for conduction under associated phases of said input power source;
- a DC voltage source, DC chopper means coupled between said DC voltage source and said plurality of main switches, said DC chopper means including cyclically controlled unilateral auxiliary switching means for applying a reverse voltage represented by the difference between said DC voltage and the line to neutral input voltage to said main switches, said reverse voltage being larger than the incoming line voltage for any conducting one of said main switches and with said auxiliary switching means being controlled for conduction at an instant subsequent to conduction of one of said main switches to apply said reverse voltage thereto and to establish a temporary path for the load current in derivation to said conductive one of said main switches, thereby to commutate conduction from said one main switch to the next main switch being controlled for conduction.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. An AC to AC static frequency changer apparatus having first and second terminals for developing a polyphase AC output voltage of a predetermined frequency at one of said first and second terminals from a polyphase AC input voltage of a given frequency applied at the other of said first and second terminals for power flow therebetween comprising a plurality of unilateral main switching means cyclically and temporarily controlled for conduction, said main switching means being associated in pairs with the respective phases of the input terminals, and a DC voltage source, DC chopper means coupled between said DC voltage source and said plurality of main switches, said DC chopper means including cyclically controlled unilateral auxiliary switching means for applying a reverse voltage represented by the difference between said DC voltage and the line to neutral input voltage to said main switches, said reverse voltage being larger than the incoming line voltage for any conducting one of said main switches and with said auxiliary switching means being controlled for conduction at an instant subsequent to conduction of one of said main switches to apply said reverse voltage thereto and to establish a temporary path for the load current in derivation to said conductive one of said main switches, thereby to commutate conduction from said one main switch to the next main switch being controlled for conduction.
Specification