Arrangement of parallel static ac power sources proportions

Claim 2

An arrangement of parallel static AC power sources autonomously assuming the proper proportions of load current compRising: first and second converter circuits connected in parallel; first current sensing means to produce a signal representative of the output load current of said first converter; first phasing means responsive to the signal from said first current sensing means to produce a first control signal representative of a first component of the load current of said first converter and a second control signal representative of a second component of the load current of said first converter, said second signal component being in quadrature with said first component; first control means comprising a voltage reference source, a voltage summing node and an error amplifier, said voltage reference source providing a voltage reference signal, said voltage reference signal and said first control signal being applied to said voltage summing node, said error amplifier controlling the voltage amplitude of said first converter in response to the difference between the output of said voltage summing node and a similarly scaled representation of the amplitude of the output voltage of said first converter, said first control means being responsive to said first control signal produced by said first phasing means to control the amplitude of the voltage of said first converter in such a fashion as to cause said first proportion converter to tend to supply a constant predetermined proportion of the total load current; second control means responsive to said second control signal produced by said first phasing means to control the frequency of the voltage of said first converter in such a fashion as to cause said first converter to tend to supply a constant predetermined proportion of the total load current; and an external input to said voltage summing node to adjust the amplitude of the voltage of said first converter in proportion to a similar adjustment in the amplitude of the voltage of said second converter,

Claim 3

An arrangement of parallel static AC power sources autonomously assuming the proper proportions of load current comprising: first and second converter circuits connected in parallel; first current sensing means to produce a signal representative of the output load current of said first converter; first phasing means responsive to the signal from said first current sensing means to produce a first control signal representative of a first component of the load current of said first converter and a second control signal representative of a second component of the load current of said first converter, said second signal component being in quadrature with said first component; first control means responsive to said first control signal produced by said first phasing means to control the amplitude of the voltage of said first converter in such a fashion as to cause said first proportion converter to tend to supply a constant predetermined proportion of the total load current; second control means comprising a frequency reference source, a frequency summing node and a voltage controlled oscillator, said frequency reference source providing a frequency reference signal, said frequency reference signal and said second control signal being applied to said frequency summing node, said voltage controlled oscillator being responsive to the output of said frequency summing node to control the frequency of the voltage of said first converter, said second control means being responsive to said second control signal produced by said first phasing means to control the frequency of the voltage of said first converter in such a fashion as to cause said first converter to tend to supply a constant predetermined proportion of the total load current; and an external input to said frequency summing node to adjust the frequency of the voltage of said first converter in proportion to a similar adjustment in the frequency of said second converter.

Claim 4

An arrangement of parallel static AC power sources autonomously assuming the proper proportions of load current comprising: first and second converter circuits connected in parallel; first current sensing means to produce a signal representative of the output load current of said first converter; first phasing means responsive to the signal from said first current sensing means to produce a first control signal representative of a first component of the load current of said first converter and a second control signal representative of a second component of the load current of said first converter, said second signal component being in quadrature with said first component; first control means responsive to said first control signal produced by said first phasing means to control the amplitude of the voltage of said first converter in such a fashion as to cause said first proportion converter to tend to supply a constant predetermined proportion of the total load current; second control means comprising a frequency reference source, a frequency summing node and a voltage controlled oscillator, said frequency reference source providing a frequency reference signal, said frequency reference signal and said second control signal being applied to said frequency summing node, said voltage controlled oscillator being responsive to the output of said frequency summing node to control the frequency of the voltage of said first converter, said second control means being responsive to said second control signal produced by said first phasing means to control the frequency of the voltage of said first converter in such a fashion as to cause said first converter to tend to supply a constant predetermined proportion of the total load current; and an external input to said frequency summing node to adjust the frequency of the voltage of said first converter in proportion to a similar adjustment in the frequency of said second converter.

Claim 5

An arrangement of parallel static AC power sources autonomously assuming the proper proportions of load currEnt comprising: first and second converter circuits connected in parallel; first current sensing means to produce a signal representative of the output load current of said first converter; first phasing means responsive to the signal from said first current sensing means to produce a first control signal representative of a first component of the load current of said first converter and a second control signal representative of a second component of the load current of said first converter, said second signal component being in quadrature with said first component; first control means responsive to said first control signal produced by said first phasing means to control the amplitude of the voltage of said first converter in such a fashion as to cause said first proportion converter to tend to supply a constant predetermined proportion of the total load current; second control means responsive to said second control signal produced by said first phasing means to control the frequency of the voltage of said first converter in such a fashion as to cause said first converter to tend to supply a constant predetermined proportion of the total load current; switching means to selectively connect said first converter to the load; and prephasing means to assure that the voltage of said first converter is in phase with the load voltage when said switching means disconnect said first converter from the load, in order that upon actuating of said switching means to connect said first converter to the load no circulating currents are produced as a result of phase differences between the load voltage and the voltage of said first converter.

Claim 6

An arrangement of parallel static AC power sources autonomously assuming the proper proportions of load currEnt comprising: first and second converter circuits connected in parallel; first current sensing means to produce a signal representative of the output load current of said first converter; first phasing means responsive to the signal from said first current sensing means to produce a first control signal representative of a first component of the load current of said first converter and a second control signal representative of a second component of the load current of said first converter, said second signal component being in quadrature with said first component; first control means responsive to said first control signal produced by said first phasing means to control the amplitude of the voltage of said first converter in such a fashion as to cause said first proportion converter to tend to supply a constant predetermined proportion of the total load current; second control means responsive to said second control signal produced by said first phasing means to control the frequency of the voltage of said first converter in such a fashion as to cause said first converter to tend to supply a constant predetermined proportion of the total load current; switching means to selectively connect said first converter to the load; and prephasing means to assure that the voltage of said first converter is in phase with the load voltage when said switching means disconnect said first converter from the load, in order that upon actuating of said switching means to connect said first converter to the load no circulating currents are produced as a result of phase differences between the load voltage and the voltage of said first converter.

Claim 7

An arrangement of parallel sources of AC power autonomously assuming the proper proportions of load current comprising: a plurality of three phase converters adapted to be connected in parallel to a common load; a current transformer for each phase of a first one of said converters, each of said current transformers producing a signal representative of the output load current of the corresponding phase of said first converter; a phasing network for each phase of said first converter, each of said phasing networks responsive to a related one of said current transformers to produce a first phasing signal component along an axis at a predetermined angle with respect to the phasor of the output load current of said first converter and a second phasing signal component in quadrature therewith, said first and second signal components having amplitudes proportional to the load current of the corresponding phase of said first converter; a reference source to provide reference signals, each reference signal having the phase of the load current of a corresponding phase of said first converter; a first phase sensitive demodulator for each phase of said first converter, each of said first phase sensitive demodulators responsive to said first phasing signal component and said reference signal for the corresponding phase of said first converter to produce a first control signal representative of a first component of the load current for that phase of said first converter; a second phase sensitive demodulator for each phase of said first converter, each of said second phase sensitive demodulators responsive to said second phasing signal component and said reference signal for the corresponding phase of said first converter to produce a second control signal representative of a second component of the load current for that phase of said first converter; a first voltage summing node to which the outputs of said first phase sensitive demodulators are applied to produce a composite first control signal; a voltage reference source to provide a voltage reference signal; a second voltage summing node to which said composite first control signal and said voltage reference signal are applied; an error amplifier to control the voltage amplitude of said first converter iN response to the difference between the output of said second voltage summing node and a similarly sealed representation of amplitude of the output voltage of said first converter; a first frequency summing node to which the output of said second phase sensitive demodulators are applied to produce a composite second control signal; a frequency reference source to provide a frequency reference signal; a second frequency summing node to which said composite second control signal and said frequency reference signal are applied; and a voltage controlled oscillator responsive to the output of said second frequency summing node to control the frequency of the voltage of said first converter.

Claim 8

An arrangement of parallel sources of AC power autonomously assuming the proper proportions of load current comprising: a plurality of three phase converters adapted to be connected in parallel to a common load; a current transformer for each phase of a first one of said converters, each of said current transformers producing a signal representative of the output load current of the corresponding phase of said first converter; a phasing network for each phase of said first converter, each of said phasing networks responsive to a related one of said current transformers to produce a first phasing signal component along an axis at a predetermined angle with respect to the phasor of the output load current of said first converter and a second phasing signal component in quadrature therewith, said first and second signal components having amplitudes proportional to the load current of the corresponding phase of said first converter; a reference source to provide reference signals, each reference signal having the phase of the load current of a corresponding phase of said first converter; a first phase sensitive demodulator for each phase of said first converter, each of said first phase sensitive demodulators responsive to said first phasing signal component and said reference signal for the corresponding phase of said first converter to produce a first control signal representative of a first component of the load current for that phase of said first converter; a second phase sensitive demodulator for each phase of said first converter, each of said second phase sensitive demodulators responsive to said second phasing signal component and said reference signal for the corresponding phase of said first converter to produce a second control signal representative of a second component of the load current for that phase of said first converter; a first voltage summing node to which the outputs of said first phase sensitive demodulators are applied to produce a composite first control signal; a voltage reference source to provide a voltage reference signal; a second voltage summing node to which said composite first control signal and said voltage reference signal are applied; an error amplifier to control the voltage amplitude of said first converter iN response to the difference between the output of said second voltage summing node and a similarly sealed representation of amplitude of the output voltage of said first converter; a first frequency summing node to which the output of said second phase sensitive demodulators are applied to produce a composite second control signal; a frequency reference source to provide a frequency reference signal; a second frequency summing node to which said composite second control signal and said frequency reference signal are applied; and a voltage controlled oscillator responsive to the output of said second frequency summing node to control the frequency of the voltage of said first converter.

Claim 9

An arrangement as claimed in claim 4 and further comprising: switching means to selectively connect said first converter to the load; and prephasing means to assure that the voltage of said first converter is in phase with the load voltage when said switching means disconnect said first converter from the load, in order that upon actuation of said switching means to connect said first converter to the load no circulating currents are produced as a result of phase differences between the load voltage and the voltage of said first converter.

Claim 10

An arrangement as claimed in claim 5 wherein said prephasing means comprises a third phase sensitive demodulator responsive to one line-to-line voltage on the load side of said switching means and the other line-to-line voltages taken from the converter side of said switching means, the output of said third phase sensitive demodulator being applied to said second frequency summing node.

Claim 11

An arrangement as claimed in claim 6 and further comprising external inputs to said second voltage summing node and said second frequency summing node to adjust the amplitude and frequency, respectively, of said first converter in proportion to similar adjustments in the amplitude and frequency of the voltage of the other converters.

Claim 12

An arrangement for causing parallel static AC generators to autonomously assume the proper proportion of a load current comprising: first current detecting means to determine a magnitude of a first component of the output current of a selected one of the static AC generators and produce a first control signal representative thereof; second current detecting means to determine the magnitude of a second component of the output current to the selected static AC generator and produce a second control signal representative thereof, said second component being in quadrature with said first component; first control means responsive to said first control signal produced by said first current detecting means to control the amplitude of the voltage of the selected first static AC generator in such a fashion as to cause the selected static AC generator to tend to supply a constant proportion of the load current; second control means responsive to said second control signal produced by said second current detecting means to control the frequency of the voltage of the selected static AC generator in such a fashion as to cause the selected static AC generator to tend to supply a constant proportion of the load current; third current detecting means to determine the magnitude of a first component of the output current of a second one of the static AC generators and produce a signal representative thereof; fourth current detecting means to determine the magnitude of a second component of the output current of the second static AC generator and produce a signal representative thereof, said second component being in quadrature with said first component; third control means responsive to the signal produced by said third current detecting means to control the amplitude of the voltage of the second static AC generator in such a fashion as to cause the second static AC generator to supply a constant proportion of the load current; fourth control means Responsive to the signal produced by said fourth current detecting means to control the phase of the voltage of the second static AC generator in such a fashion as to cause the second static AC generator to tend to apply a constant proportion of the load current; the droop gain characteristics of said first and third control means being established to provide the same maximum voltage droops at nominal output current; and the droop gain characteristics of said second and fourth control means being established to provide the same maximum frequency droop at nominal output current, whereby the two static AC generators divide the load current in proportion to their respective ratings.

Claim 13

An arrangement for causing parallel static AC generators to autonomously assume the proper proportion of a load current comprising: first current detecting means to determine a magnitude of a first component of the output current of a selected one of the static AC generators and produce a first control signal representative thereof; second current detecting means to determine the magnitude of a second component of the output current to the selected static AC generator and produce a second control signal representative thereof, said second component being in quadrature with said first component; first control means responsive to said first control signal produced by said first current detecting means to control the amplitude of the voltage of the selected first static AC generator in such a fashion as to cause the selected static AC generator to tend to supply a constant proportion of the load current; second control means responsive to said second control signal produced by said second current detecting means to control the frequency of the voltage of the selected static AC generator in such a fashion as to cause the selected static AC generator to tend to supply a constant proportion of the load current; third current detecting means to determine the magnitude of a first component of the output current of a second one of the static AC generators and produce a signal representative thereof; fourth current detecting means to determine the magnitude of a second component of the output current of the second static AC generator and produce a signal representative thereof, said second component being in quadrature with said first component; third control means responsive to the signal produced by said third current detecting means to control the amplitude of the voltage of the second static AC generator in such a fashion as to cause the second static AC generator to supply a constant proportion of the load current; fourth control means Responsive to the signal produced by said fourth current detecting means to control the phase of the voltage of the second static AC generator in such a fashion as to cause the second static AC generator to tend to apply a constant proportion of the load current; the droop gain characteristics of said first and third control means being established to provide the same maximum voltage droops at nominal output current; and the droop gain characteristics of said second and fourth control means being established to provide the same maximum frequency droop at nominal output current, whereby the two static AC generators divide the load current in proportion to their respective ratings.