Cycloconverter trigger timing system

Claim 1

A system for supplying an alternating signal at a desired frequency to a load comprising: a polyphase voltage generator for generating polyphase line-to-neutral voltages; a converter coupled between the voltage generator and the load including a pair of polyphase full wave bridge rectifiers, one of said pair of bridge rectifiers including a first set of controlled rectifiers poled for supplying positive current to the load and a second set of controlled rectifiers poled for returning said positive current to the voltage generator and the other of said pair of bridge rectifiers including a third set of controlled rectifiers poled for supplying negative current to the load and a fourth set of controlled rectifiers poled for returning said negative current to the voltage generator; means for generating a number of waveforms each having alternating states, each state representing the firing angle range of a respective controlled rectifier in each fullwave bridge rectifier; means for generating a number of source reference waveforms each having an instantaneous amplitude representing the firing delay angle of a respective controlled rectifier in each full-wave bridge rectifier and having a fast falling trailing edge, the state of the waveform representing the firing angle range of one of the controlled rectifiers coinciding with the source reference waveform whose instantaneous amplitude represents the firing delay angle thereof; means for generating a series of square waves at the desired frequency of the alternating signal, each of said square waves having alternating first and second states; means for generating a series of load reference waveforms having a period coincident with each state of the square waves, each load reference waveform having an instantaneous amplitude representing a desired controlled rectifier firing delay angle and having a fast falling trailing edge; comparator means responsive to the amplitudes of the source reference waveforms and the load reference waveforms for generating firing commands for each of the controlled rectifiers; a number of bistable multivibrators, each of said multivibrators having an output coupled to a respective one of the controlled rectifiers in the pair of full wave bridge rectifiers; means for selectively setting the multivibrators coupled to the controlled rectifiers in the first and second sets to selectively gate said controlled rectifiers into conduction, each one of said last mentioned multivibrators being set upon the simultaneous occurrence of the first state of the square wave signal, the state of the waveform representing the firing angle range of the controlled rectifier coupled thereto and the firing command for the controlled rectifier coupled thereto; means for selectively setting the multivibrators coupled to the controlled rectifiers in the third and fourth sets to selectively gate said controlled rectifiers into conduction, each one of said last mentioned multivibrators being set upon the simultaneous occurrence of the second state of the square wave signal, the state of the waveform representing the firing angle range of the controlled rectifier coupled thereto and the firing command for the controlled rectifier coupled thereto; and means for resetting each multivibrator coupled to a controlled rectifier in a respective one of the first, second, third and fourth sets upon the setting of another one of the multivibrators coupled to a controlled recTifier in the same set, whereby the controlled rectifiers in the pair of full wave bridge rectifiers are selectively gated into conduction to supply the alternating signal at the desired frequency to the load.

Claim 2

A system for supplying an alternating signal at a desired frequency to a load comprising: a polyphase voltage generator for generating polyphase line-to-neutral voltages; a converter coupled between the voltage generator and the load including a pair of polyphase full wave bridge rectifiers, one of said pair of bridge rectifiers including a first set of controlled rectifiers poled for supplying positive current to the load and a second set of controlled rectifiers poled for returning said positive current to the voltage generator and the other of said pair of bridge rectifiers including a third set of controlled rectifiers poled for supplying negative current to the load and a fourth set of controlled rectifiers poled for returning said negative current to the voltage generator; means for generating a number of waveforms each having alternating states, each state representing the firing angle range of a respective controlled rectifier in each fullwave bridge rectifier; means for generating a number of source reference waveforms each having an instantaneous amplitude representing the firing delay angle of a respective controlled rectifier in each full-wave bridge rectifier and having a fast falling trailing edge, the state of the waveform representing the firing angle range of one of the controlled rectifiers coinciding with the source reference waveform whose instantaneous amplitude represents the firing delay angle thereof; means for generating a series of square waves at the desired frequency of the alternating signal, each of said square waves having alternating first and second states; means for generating a series of load reference waveforms having a period coincident with each state of the square waves, each load reference waveform having an instantaneous amplitude representing a desired controlled rectifier firing delay angle and having a fast falling trailing edge; comparator means responsive to the amplitudes of the source reference waveforms and the load reference waveforms for generating firing commands for each of the controlled rectifiers; a number of bistable multivibrators, each of said multivibrators having an output coupled to a respective one of the controlled rectifiers in the pair of full wave bridge rectifiers; means for selectively setting the multivibrators coupled to the controlled rectifiers in the first and second sets to selectively gate said controlled rectifiers into conduction, each one of said last mentioned multivibrators being set upon the simultaneous occurrence of the first state of the square wave signal, the state of the waveform representing the firing angle range of the controlled rectifier coupled thereto and the firing command for the controlled rectifier coupled thereto; means for selectively setting the multivibrators coupled to the controlled rectifiers in the third and fourth sets to selectively gate said controlled rectifiers into conduction, each one of said last mentioned multivibrators being set upon the simultaneous occurrence of the second state of the square wave signal, the state of the waveform representing the firing angle range of the controlled rectifier coupled thereto and the firing command for the controlled rectifier coupled thereto; and means for resetting each multivibrator coupled to a controlled rectifier in a respective one of the first, second, third and fourth sets upon the setting of another one of the multivibrators coupled to a controlled recTifier in the same set, whereby the controlled rectifiers in the pair of full wave bridge rectifiers are selectively gated into conduction to supply the alternating signal at the desired frequency to the load.

Claim 3

A system for supplying an alternating signal at a desired frequency to a load comprising: a polyphase voltage generator for generating polyphase line-to-neutral voltages; a converter coupled between the voltage generator and the load including a pair of polyphase full wave bridge rectifiers, one of said pair of bridge rectifiers including a first set of controlled rectifiers poled for supplying positive current to the load and a second set of controlled rectifiers poled for returning said positive current to the voltage generator and the other of said pair of bridge rectifiers including a third set of controlled rectifiers poled for supplying negative current to the load and a fourth set of controlled rectifiers poled for returning said negative current to the voltage generator; means coupled to the voltage generator and responsive to each line-to-line voltage therefrom for generating a respective series of source reference waveforms synchronized with each line-to-line zero voltage crossover, each source reference waveform having a first state coincident with the firing angle range of a respective controlled rectifier in each of the first and third sets of controlled rectifiers and a second state coincident with the firing angle range of a respective controlled rectifier in each of the second and fourth sets of controlled rectifiers; means responsive to each series of source reference waveforms for generating a respective series of sawtooth waveforms having a period coincident with each state thereof, each sawtooth waveform having an instantaneous amplitude directly proportional to the firing delay angle of the controlled rectifiers whose firing angle range is represented by the state of the source reference waveform coincident therewith; means for generating a series of square waves at the desired frequency, each of said square waves having first and second states; means for generating a series of load reference signals having a period coincident with each state of the series of square waves, each load reference signal having an instantaneous amplitude representing a desired controlled rectifier firing delay angle and having a fast falling trailing edge; comparator means for individually comparing the instantaneous amplitude of each of the series of sawtooth waveforms with the instantaneous amplitude of the series of load reference signals and generating respective series of clock pulses, each clock pulse having a triggering edge occurring when the instantaneous magnitude of the series of load reference signals equals the instantaneous magnitude of a respective one of the sawtooth waveforms, said triggering edge representing a firing command for the controlled rectifiers whose firing delay angle is represented by said sawtooth waveform; a number of bistable multivibrators, each of said multivibrators having an output coupled to a respective one of the controlled rectifiers in the pair of full wave bridge rectifiers; means for selectively setting the multivibrators coupled to the controlled rectifiers in the first and second sets to selectively gate said controlled rectifiers into conduction, each one of said last mentioned multivibrators being set upon the simultaneous occurrence of the first state of the series of square waves, the state of the source reference waveform coincident with the firing angle range of the controlled rectifier coupled thereto and the firing command for the controlled rectifier coupled thereto; means for selectively setting the multivibrators coupled to the controlled rectifiers in the third and fourth sets to selectively gate said controlled rectifiers into conduction, each one of said last mentioned multivibrators being set upon the simultaneous occurrence of the second state of the series of square waves, the state of the source refeRence waveform coincident with the firing angle range of the controlled rectifier coupled thereto and the firing command for the controlled rectifier coupled thereto; and means for resetting each multivibrator coupled to a controlled rectifier in a respective one of the first, second, third and fourth sets upon the setting of another one of the multivibrators coupled to a controlled rectifier in the same set, whereby the controlled rectifiers in the pair of full wave bridge rectifiers are selectively gated into conduction to supply the alternating signal at the desired frequency to the load.

Claim 4

A system for supplying an alternating signal at a desired frequency to a load comprising: a polyphase voltage generator for generating polyphase line-to-neutral voltages; a converter coupled between the voltage generator and the load including a pair of polyphase full wave bridge rectifiers, one of said pair of bridge rectifiers including a first set of controlled rectifiers poled for supplying positive current to the load and a second set of controlled rectifiers poled for returning said positive current to the voltage generator and the other of said pair of bridge rectifiers including a third set of controlled rectifiers poled for supplying negative current to the load and a fourth set of controlled rectifiers poled for returning said negative current to the voltage generator; means coupled to the voltage generator and responsive to each line-to-line voltage therefrom for generating a respective series of source reference waveforms synchronized with each line-to-line zero voltage crossover, each source reference waveform having a first state coincident with the firing angle range of a respective controlled rectifier in each of the first and third sets of controlled rectifiers and a second state coincident with the firing angle range of a respective controlled rectifier in each of the second and fourth sets of controlled rectifiers; means responsive to each series of source reference waveforms for generating a respective series of sawtooth waveforms having a period coincident with each state thereof, each sawtooth waveform having an instantaneous amplitude directly proportional to the firing delay angle of the controlled rectifiers whose firing angle range is represented by the state of the source reference waveform coincident therewith; means for generating a series of square waves at the desired frequency, each of said square waves having first and second states; means for generating a series of load reference signals having a period coincident with each state of the series of square waves, each load reference signal having an instantaneous amplitude representing a desired controlled rectifier firing delay angle and having a fast falling trailing edge; comparator means for individually comparing the instantaneous amplitude of each of the series of sawtooth waveforms with the instantaneous amplitude of the series of load reference signals and generating respective series of clock pulses, each clock pulse having a triggering edge occurring when the instantaneous magnitude of the series of load reference signals equals the instantaneous magnitude of a respective one of the sawtooth waveforms, said triggering edge representing a firing command for the controlled rectifiers whose firing delay angle is represented by said sawtooth waveform; a number of bistable multivibrators, each of said multivibrators having an output coupled to a respective one of the controlled rectifiers in the pair of full wave bridge rectifiers; means for selectively setting the multivibrators coupled to the controlled rectifiers in the first and second sets to selectively gate said controlled rectifiers into conduction, each one of said last mentioned multivibrators being set upon the simultaneous occurrence of the first state of the series of square waves, the state of the source reference waveform coincident with the firing angle range of the controlled rectifier coupled thereto and the firing command for the controlled rectifier coupled thereto; means for selectively setting the multivibrators coupled to the controlled rectifiers in the third and fourth sets to selectively gate said controlled rectifiers into conduction, each one of said last mentioned multivibrators being set upon the simultaneous occurrence of the second state of the series of square waves, the state of the source refeRence waveform coincident with the firing angle range of the controlled rectifier coupled thereto and the firing command for the controlled rectifier coupled thereto; and means for resetting each multivibrator coupled to a controlled rectifier in a respective one of the first, second, third and fourth sets upon the setting of another one of the multivibrators coupled to a controlled rectifier in the same set, whereby the controlled rectifiers in the pair of full wave bridge rectifiers are selectively gated into conduction to supply the alternating signal at the desired frequency to the load.

Claim 5

A system for supplying an alternating signal at a desired frequency to a load comprising: a polyphase voltage generator for generating polyphase line-to-neutral voltages; a converter coupled between the voltage generator and the load including a pair of polyphase full wave bridge rectifiers, one of said pair of bridge rectifiers including a first set of controlled rectifiers poled for supplying positive current to the load and a second set of controlled rectifiers poled for returning said positive current to the voltage generator and the other of said pair of bridge rectifiers including a third set of controlled rectifiers poled for supplying negative current to the load and a fourth set of controlled rectifiers poled for returning said negative current to the voltage generator; means coupled to the voltage generator and responsive to each line-to-line voltage therefrom for generating a respective series of source reference waveforms synchronized with each line-to-line zero voltage crossover, each source reference waveform having a first state coincident with the firing angle range of a respective controlled rectifier in each of the first and third sets of controlled rectifiers and a second state coincident with the firing angle range of a respective controlled rectifier in each of the second and fourth sets of controlled rectifiers; means responsive to each series of source reference waveforms for generating a respective series of sawtooth waveforms having a period of coincident with each state thereof, each sawtooth waveform having an instantaneous amplitude directly proportional to the firing delay angle of the controlled rectifiers whose firing angle range is represented by the state of the source reference waveform coincident therewith; means for generating a series of square waves at the desired frequency, each of said square waves having first and second states; means for generating a series of load reference signals having a period coincident with each state of the series of square waves, each load reference signal having an instantaneous amplitude representing a desired controlled rectifier firing delay angle and having a fast falling trailing edge; comparator means for individually comparing the instantaneous amplitude of each of the series of sawtooth waveforms with the instantaneous amplitude of the series of load reference signals and generating respective series of clock pulses, each clock pulse having a triggering edge occurring when the instantaneous magnitude of the series of load reference signals equals the instantaneous magnitude of a respective one of the sawtooth waveforms, said triggering edge representing a firing command for the controlled rectifiers whose firing delay angle is represented by said sawtooth waveform; a number of bistable multivibrators, each of said multivibrators having an output coupled to a respective one of the controlled rectifiers in the pair of full wave bridge rectifiers; means for selectively setting the multivibrators coupled to the controlled rectifiers in the first and second sets to generate trigger signals to selectively gate said controlled rectifiers into conduction, each one of said last mentioned multivibrators being set upon the simultaneous occurrence of the first state of the series of square waves, the state of the source reference waveform coincident with the firing angle range of the controlled rectifier coupled thereto and The firing command for the controlled rectifier coupled thereto; means for selectively setting the multivibrators coupled to the controlled rectifiers in the third and fourth sets to generate trigger signals to selectively gate said controlled rectifiers into conduction, each one of said last mentioned multivibrators being set upon the simultaneous occurrence of the second state of the series of square waves, the state of the source reference waveform coincident with the firing angle range of the controlled rectifier coupled thereto and the firing command for the controlled rectifier coupled thereto; means for resetting each multi-vibrator coupled to a controlled rectifier in a respective one of the first, second, third and fourth sets upon the setting of another one of the multivibrators coupled to a controlled rectifier in the same set; and a number of inhibit circuits, each having an output coupled to the output of a respective one of the multivibrators, each one of the inhibit circuits coupled to a respective one of the multivibrators generating a trigger signal for a controlled rectifier in one of the pair of full wave bridge rectifiers being responsive to the coexistence of the trigger signal generated by the multivibrator for the controlled rectifier in the other one of the pair of full wave bridge rectifiers which could conduct with said controlled rectifier in the first mentioned one of the pair of full wave bridge rectifiers and the state of the series of source reference waveforms representing the period of possible conduction between said controlled rectifiers in the pair of full wave bridge rectifiers for inhibiting the generation of a trigger signal waveform for inhibiting the generation of a gate signal and each of the inhibiting circuits coupled to the output of the gate signal generators controlling the controlled switches in the third and fourth sets each being responsive to the coexistence of the state of one of the source reference waveforms and the generation of a gating signal for the controlled switch in the first and second groups which would conduct therewith during said state of the source reference waveform for inhibiting the generation of a gate signal whereby the controlled rectifiers in the pair of full wave bridge rectifiers are selectively gated conductive to supply an alternating signal at the desired frequency to the load.

Claim 6

A system for supplying an alternating signal at a desired frequency to a load comprising: a polyphase voltage generator for generating polyphase line-to-neutral voltages; a converter coupled between the voltage generator and the load including a pair of polyphase full wave bridge rectifiers, one of said pair of bridge rectifiers including a first set of controlled rectifiers poled for supplying positive current to the load and a second set of controlled rectifiers poled for returning said positive current to the voltage generator and the other of said pair of bridge rectifiers including a third set of controlled rectifiers poled for supplying negative current to the load and a fourth set of controlled rectifiers poled for returning said negative current to the voltage generator; means coupled to the voltage generator and responsive to each line-to-line voltage therefrom for generating a respective series of source reference waveforms synchronized with each line-to-line zero voltage crossover, each source reference waveform having a first state coincident with the firing angle range of a respective controlled rectifier in each of the first and third sets of controlled rectifiers and a second state coincident with the firing angle range of a respective controlled rectifier in each of the second and fourth sets of controlled rectifiers; means responsive to each series of source reference waveforms for generating a respective series of sawtooth waveforms having a period of coincident with each state thereof, each sawtooth waveform having an instantaneous amplitude directly proportional to the firing delay angle of the controlled rectifiers whose firing angle range is represented by the state of the source reference waveform coincident therewith; means for generating a series of square waves at the desired frequency, each of said square waves having first and second states; means for generating a series of load reference signals having a period coincident with each state of the series of square waves, each load reference signal having an instantaneous amplitude representing a desired controlled rectifier firing delay angle and having a fast falling trailing edge; comparator means for individually comparing the instantaneous amplitude of each of the series of sawtooth waveforms with the instantaneous amplitude of the series of load reference signals and generating respective series of clock pulses, each clock pulse having a triggering edge occurring when the instantaneous magnitude of the series of load reference signals equals the instantaneous magnitude of a respective one of the sawtooth waveforms, said triggering edge representing a firing command for the controlled rectifiers whose firing delay angle is represented by said sawtooth waveform; a number of bistable multivibrators, each of said multivibrators having an output coupled to a respective one of the controlled rectifiers in the pair of full wave bridge rectifiers; means for selectively setting the multivibrators coupled to the controlled rectifiers in the first and second sets to generate trigger signals to selectively gate said controlled rectifiers into conduction, each one of said last mentioned multivibrators being set upon the simultaneous occurrence of the first state of the series of square waves, the state of the source reference waveform coincident with the firing angle range of the controlled rectifier coupled thereto and The firing command for the controlled rectifier coupled thereto; means for selectively setting the multivibrators coupled to the controlled rectifiers in the third and fourth sets to generate trigger signals to selectively gate said controlled rectifiers into conduction, each one of said last mentioned multivibrators being set upon the simultaneous occurrence of the second state of the series of square waves, the state of the source reference waveform coincident with the firing angle range of the controlled rectifier coupled thereto and the firing command for the controlled rectifier coupled thereto; means for resetting each multi-vibrator coupled to a controlled rectifier in a respective one of the first, second, third and fourth sets upon the setting of another one of the multivibrators coupled to a controlled rectifier in the same set; and a number of inhibit circuits, each having an output coupled to the output of a respective one of the multivibrators, each one of the inhibit circuits coupled to a respective one of the multivibrators generating a trigger signal for a controlled rectifier in one of the pair of full wave bridge rectifiers being responsive to the coexistence of the trigger signal generated by the multivibrator for the controlled rectifier in the other one of the pair of full wave bridge rectifiers which could conduct with said controlled rectifier in the first mentioned one of the pair of full wave bridge rectifiers and the state of the series of source reference waveforms representing the period of possible conduction between said controlled rectifiers in the pair of full wave bridge rectifiers for inhibiting the generation of a trigger signal waveform for inhibiting the generation of a gate signal and each of the inhibiting circuits coupled to the output of the gate signal generators controlling the controlled switches in the third and fourth sets each being responsive to the coexistence of the state of one of the source reference waveforms and the generation of a gating signal for the controlled switch in the first and second groups which would conduct therewith during said state of the source reference waveform for inhibiting the generation of a gate signal whereby the controlled rectifiers in the pair of full wave bridge rectifiers are selectively gated conductive to supply an alternating signal at the desired frequency to the load.