Dc protection and control panel with generator field excitation control

Claim 2

In the method of regulating the output voltage of a DC generator by energizing the field in accordance with the output voltage of the generator the improvement which comprises periodically energizing the field for lengths of time varying in accordance with generator output voltage and at intervals that are substantially shorter than the response time of the generator to applied or removed field excitation and are substantially independent of variations in the output voltage of the generator whereby the mechanical system of the generator is incapable of following the individual energization signals.

Claim 3

The method as defined in claim 1 wherein the field is energized at intervals about 1/10 of the response time of the generator to applied or removed field excitation.

Claim 6

The method as defined in claim 3 wherein the field is energized at intervals about 1/10 of the response time of the shaft to a torsional input.

Claim 7

In a power system including a DC generator, said generator having an output providing an output voltage and a field winding, a prime mover, an energy-absorbing shaft connected between said generator and said prime mover for transmitting torque therebetween, and a DC power source connected in parallel with the output of said generator, a circuit for controlling the field excitation of said DC generator to regulate its output voltage, said circuit comprising means for sensing the output voltage level of said generator and providing an output voltage signal proportional thereto, reference voltage means for providing a reference voltage proportional to a predetermined generator output voltage, means for providing a periodic alternating waveform signal, the period of said signal being substantially less than the response time of said shaft to a torsional input produced by applied or remOved field excitation, static means for algebraically combining said generator output voltage signal and said periodic alternating waveform signal to provide an output signal comprising a periodic alternating waveform superimposed upon a direct current voltage level proportional to the output voltage of said generator so that, by comparison with said reference voltage, the level of said alternating waveform falls below the level of said reference voltage with a frequency corresponding to the frequency of said alternating waveform and for greater and lesser periods of time dependent upon the relative levels of said direct current voltage upon which it is superimposed and said reference voltage, static-comparing and bistable switching means having a first input connected to said static means and a second input connected to said voltage reference means and having output means for connecting and disconnecting said field winding and said generator output to control the excitation of said generator when said bistable means assumes one and the other, respectively, of its stable states, said comparing and bistable switching means being responsive to said input signals to assume said one of its stable states when said alternating waveform voltage falls below said reference voltage and to assume said other of its stable states when said alternating waveform voltage exceeds said reference voltage, said comparing and bistable switching means assuming one or the other of its stable states at intervals substantially independent of variations in the output voltage of said generator whereby said field winding is provided pulses of excitation current at a frequency corresponding to the frequency of said alternating waveform voltage and of shorter and longer duration as the output voltage of said generator exceeds and falls below, respectively, the level of said reference voltage, said static-comparing and bistable switching means comprising, an operational amplifier, a static power switch directly controlling current flow from the output of said controlled generator to said field winding, a static control switch connected to the output of said operational amplifier and connected in controlling relationship to said static power switch, said operational amplifier having an inverting and a noninverting input as said first and second inputs, respectively, and an output providing positive and negative square wave output signals when said inverting input level is less and more, respectively, than said noninverting input level, said control switch being responsive to the output of said operational amplifier whereby said control switch conducts when the output of said operational amplifier is negative and blocks when the output of said operational amplifier is positive, and said power switch being responsive to the state of said control switch whereby said power switch conducts excitation current to said field winding when said control switch blocks, and blocks excitation current to said field winding when said control switch conducts.

Claim 8

In a power system including a DC generator, said generator having an output providing an output voltage and a field winding, a prime mover, an energy-absorbing shaft connected between said generator and said prime mover for transmitting torque therebetween, and a DC power source connected in parallel with the output of said generator, a circuit for controlling the field excitation of said DC generator to regulate its output voltage, said circuit comprising means for sensing the output voltage level of said generator and providing an output voltage signal proportional thereto, reference voltage means for providing a reference voltage proportional to a predetermined generator output voltage, means for providing a periodic alternating waveform signal, the period of said signal being substantially less than the response time of said shaft to a torsional input produced by applied or remOved field excitation, static means for algebraically combining said generator output voltage signal and said periodic alternating waveform signal to provide an output signal comprising a periodic alternating waveform superimposed upon a direct current voltage level proportional to the output voltage of said generator so that, by comparison with said reference voltage, the level of said alternating waveform falls below the level of said reference voltage with a frequency corresponding to the frequency of said alternating waveform and for greater and lesser periods of time dependent upon the relative levels of said direct current voltage upon which it is superimposed and said reference voltage, static-comparing and bistable switching means having a first input connected to said static means and a second input connected to said voltage reference means and having output means for connecting and disconnecting said field winding and said generator output to control the excitation of said generator when said bistable means assumes one and the other, respectively, of its stable states, said comparing and bistable switching means being responsive to said input signals to assume said one of its stable states when said alternating waveform voltage falls below said reference voltage and to assume said other of its stable states when said alternating waveform voltage exceeds said reference voltage, said comparing and bistable switching means assuming one or the other of its stable states at intervals substantially independent of variations in the output voltage of said generator whereby said field winding is provided pulses of excitation current at a frequency corresponding to the frequency of said alternating waveform voltage and of shorter and longer duration as the output voltage of said generator exceeds and falls below, respectively, the level of said reference voltage, said static-comparing and bistable switching means comprising, an operational amplifier, a static power switch directly controlling current flow from the output of said controlled generator to said field winding, a static control switch connected to the output of said operational amplifier and connected in controlling relationship to said static power switch, said operational amplifier having an inverting and a noninverting input as said first and second inputs, respectively, and an output providing positive and negative square wave output signals when said inverting input level is less and more, respectively, than said noninverting input level, said control switch being responsive to the output of said operational amplifier whereby said control switch conducts when the output of said operational amplifier is negative and blocks when the output of said operational amplifier is positive, and said power switch being responsive to the state of said control switch whereby said power switch conducts excitation current to said field winding when said control switch blocks, and blocks excitation current to said field winding when said control switch conducts.

Claim 9

The circuit as defined in claim 5 wherein the period of said alternating waveform signal is about 1/10 of the response time of said shaft to a torsional input.

Claim 10

In a power system including a DC generator, said generator having an output providing an output voltage and a field winding, a prime mover, an energy-absorbing shaft connected between said generator and said prime mover for transmitting torque therebetween, and a DC power source connected in parallel with the output of said generator, a circuit for controlling the field excitation of said DC generator to regulate its output voltage, said circuit comprising means for sensing the output voltage level of said generator and providing an output voltage signal proportional thereto, reference voltage means for providing a reference voltage proportional to a predetermined generator output voltage, means for providing a periodic alternatinG waveform signal, the period of said signal being substantially less than the response time of said shaft to a torsional input produced by applied or removed field excitation, static means for algebraically combining said generator output voltage signal and said periodic alternating waveform signal to provide an output signal comprising a periodic alternating waveform superimposed upon a direct current voltage level proportional to the output voltage of said generator so that, by comparison with said reference voltage, the level of said alternating waveform falls below the level of said reference voltage with a frequency corresponding to the frequency of said alternating waveform and for greater and lesser periods of time dependent upon the relative levels of said direct current voltage upon which it is superimposed and said reference voltage, static-comparing and bistable switching means having a first input connected to said static means and a second input connected to said voltage reference means and having output means for connecting and disconnecting said field winding and said generator output to control the excitation of said generator when said bistable means assumes one and the other, respectively, of its stable states, said comparing and bistable switching means being responsive to said input signals to assume said one of its stable states when said alternating waveform voltage falls below said reference voltage and to assume said other of its stable states when said alternating waveform voltage exceeds said reference voltage whereby said field winding is provided pulses of excitation current at a frequency corresponding to the frequency of said alternating waveform voltage and of shorter and longer duration as the output voltage of said generator exceeds and falls below, respectively, the level of said reference voltage, said static-comparing and bistable switching means comprising an operational amplifier, a static power switch directly controlling current flow from the output of said controlled generator to said field winding, a static control switch connected to the output of said operational amplifier and connected in controlling relationship to said static power switch, said operational amplifier having an inverting and a noninverting input as said first and second inputs, respectively, and an output providing positive and negative square wave output signals when said inverting input level is less and more, respectively, than said noninverting input level, said control switch being responsive to the output of said operational amplifier whereby said control switch conducts when the output of said operational amplifier is negative and blocks when the output of said operational amplifier is positive, and said power switch being responsive to the state of said control switch whereby said power switch conducts excitation current to said field winding when said control switch blocks, and blocks excitation current to said field winding when said control switch conducts.

Claim 11

In a power system including a DC generator, said generator having an output providing an output voltage and a field winding, a prime mover, an energy-absorbing shaft connected between said generator and said prime mover for transmitting torque therebetween, and a DC power source connected in parallel with the output of said generator, a circuit for controlling the field excitation of said DC generator to regulate its output voltage, said circuit comprising means for sensing the output voltage level of said generator and providing an output voltage signal proportional thereto, reference voltage means for providing a reference voltage proportional to a predetermined generator output voltage, means for providing a periodic alternatinG waveform signal, the period of said signal being substantially less than the response time of said shaft to a torsional input produced by applied or removed field excitation, static means for algebraically combining said generator output voltage signal and said periodic alternating waveform signal to provide an output signal comprising a periodic alternating waveform superimposed upon a direct current voltage level proportional to the output voltage of said generator so that, by comparison with said reference voltage, the level of said alternating waveform falls below the level of said reference voltage with a frequency corresponding to the frequency of said alternating waveform and for greater and lesser periods of time dependent upon the relative levels of said direct current voltage upon which it is superimposed and said reference voltage, static-comparing and bistable switching means having a first input connected to said static means and a second input connected to said voltage reference means and having output means for connecting and disconnecting said field winding and said generator output to control the excitation of said generator when said bistable means assumes one and the other, respectively, of its stable states, said comparing and bistable switching means being responsive to said input signals to assume said one of its stable states when said alternating waveform voltage falls below said reference voltage and to assume said other of its stable states when said alternating waveform voltage exceeds said reference voltage whereby said field winding is provided pulses of excitation current at a frequency corresponding to the frequency of said alternating waveform voltage and of shorter and longer duration as the output voltage of said generator exceeds and falls below, respectively, the level of said reference voltage, said static-comparing and bistable switching means comprising an operational amplifier, a static power switch directly controlling current flow from the output of said controlled generator to said field winding, a static control switch connected to the output of said operational amplifier and connected in controlling relationship to said static power switch, said operational amplifier having an inverting and a noninverting input as said first and second inputs, respectively, and an output providing positive and negative square wave output signals when said inverting input level is less and more, respectively, than said noninverting input level, said control switch being responsive to the output of said operational amplifier whereby said control switch conducts when the output of said operational amplifier is negative and blocks when the output of said operational amplifier is positive, and said power switch being responsive to the state of said control switch whereby said power switch conducts excitation current to said field winding when said control switch blocks, and blocks excitation current to said field winding when said control switch conducts.

Claim 12

In a system of DC generators having output terminals and an equalizer bus terminal, said DC generators being connected in parallel to a main load bus through their output terminals and to each other through connection of their equalizer terminals to an equalizer bus, a circuit for controlling the field excitation of one of said DC generators to regulate its proportionate share of the total load, said circuit comprising means for sensing current flow between said controlled generator and said equalizer and for providing an equalizer bus voltage signal proportional thereto, reference voltage means for providing a predetermined reference signal, oscillator means for providing a periodic alternating waveform signal, static means for algebraically combining said equalizer bus voltage signal and said periodic alternating waveform signal to provide an output signal comprising a periodic alternating waveform superimposed upon A direct current voltage level corresponding to the direction of equalizing current flowing between said controlled DC generator and said equalizer bus so that, by comparison with said reference voltage, the level of said alternating waveform falls below the level of said reference voltage with a frequency corresponding to the frequency of said alternating waveform and for greater and lesser periods of time dependent upon the relative levels of said direct current voltage upon which it is superimposed and said reference voltage, static-comparing and bistable switching means having a first input connected to said static means and a second input connected to said reference voltage means and having output means for connecting and disconnecting said field winding and said generator output to control the excitation of said controlled DC generator when said bistable means assumes one and the other, respectively, of its stable states, said comparing and bistable switching means being responsive to said input signals to assume one of its stable states when said alternating waveform voltage falls below said reference voltage and to assume said other of its stable states when said alternating waveform voltage exceeds said reference voltage, said comparing and bistable switching means assuming one or the other of its stable states at intervals substantially independent of variations in the output voltage of said generator whereby said field winding is provided pulses of excitation current at a frequency corresponding to the frequency of said alternating waveform and of shorter and longer duration as said controlled DC generator assumes more and less, respectively, of its proportionate share of system load on said main load bus.

Claim 13

In a system of DC generators having output terminals and an equalizer bus terminal, said DC generators being connected in parallel to a main load bus through their output terminals and to each other through connection of their equalizer terminals to an equalizer bus, a circuit for controlling the field excitation of one of said DC generators to regulate its proportionate share of the total load, said circuit comprising means for sensing current flow between said controlled generator and said equalizer and for providing an equalizer bus voltage signal proportional thereto, reference voltage means for providing a predetermined reference signal, oscillator means for providing a periodic alternating waveform signal, static means for algebraically combining said equalizer bus voltage signal and said periodic alternating waveform signal to provide an output signal comprising a periodic alternating waveform superimposed upon A direct current voltage level corresponding to the direction of equalizing current flowing between said controlled DC generator and said equalizer bus so that, by comparison with said reference voltage, the level of said alternating waveform falls below the level of said reference voltage with a frequency corresponding to the frequency of said alternating waveform and for greater and lesser periods of time dependent upon the relative levels of said direct current voltage upon which it is superimposed and said reference voltage, static-comparing and bistable switching means having a first input connected to said static means and a second input connected to said reference voltage means and having output means for connecting and disconnecting said field winding and said generator output to control the excitation of said controlled DC generator when said bistable means assumes one and the other, respectively, of its stable states, said comparing and bistable switching means being responsive to said input signals to assume one of its stable states when said alternating waveform voltage falls below said reference voltage and to assume said other of its stable states when said alternating waveform voltage exceeds said reference voltage, said comparing and bistable switching means assuming one or the other of its stable states at intervals substantially independent of variations in the output voltage of said generator whereby said field winding is provided pulses of excitation current at a frequency corresponding to the frequency of said alternating waveform and of shorter and longer duration as said controlled DC generator assumes more and less, respectively, of its proportionate share of system load on said main load bus.

Claim 14

A circuit for controlling the field excitation of a DC generator to regulate its output voltage, said circuit having an output providing an output voltage and a field winding, said circuit comprising means for sensing the output voltage level of said generator and providing an output voltage signal proportional thereto, reference voltage means for providing a reference voltage proportional to a predetermined generator output voltage, means for providing a periodic alternating waveform signal, static means for algebraically combining said generator output voltage signal and said periodic alternating waveform signal to provide an output signal comprising a periodic alternating waveform superimposed upon a direct current voltage level proportional to the output voltage of said generator so that, by comparison with said reference voltage, the level of said alternating waveform falls below the level of said reference voltage with a frequency corresponding to the frequency of said alternating waveform and for greater and lesser periods of time dependent upon the relative levels of said direct current voltage upon which it is superimposed and said reference voltage, an operational amplifier, a static power switch directly controlling current flow from the output of said controlled generator to said field winding, a static control switch connected to the output of said operational amplifier and connected in controlling relationship to said static power switch, said operational amplifier having an inverting and a noninverting input as said first and second inputs, respectively, and an output providing positive and negative square wave output signals when said inverting input level is less and more, respectively, than said noninverting input level, said control switch being responsive to the output of said operational amplifier whereby said control switch conducts when the output of said operational amplifier is negative and blocks when the output of said operational amplifier is positive, and said power switch being responsive to the state of said control switch whereby said power switch conducts excitation current to said field winding when said control switch blocks, and blocks excitation current to said field winding when said control switch conducts, said operational amplifier power requirements being provided from the output of said DC generator together with fail-safe means for insuring the continuous excitation of said DC generator in the event its output voltage falls below said operational amplifier requirements, said fail-safe means including a Zener diode having its anode connected to the output of said operational amplifier and its cathode to said control switch and the output of said DC generator whereby said Zener diode blocks and said DC generator output voltage turns off said control switch thereby turning on said power switch and supplying excitation current to said field winding when said operational amplifier output is positive, and, whereby said Zener diode conducts preventing said DC generator output voltage from turning off said power switch and preventing excitation current to flow to said winding when said operational amplifier output is negative and, whereby said Zener diode provides a fixed amount corresponding to its Zener voltage by which said DC generator output voltage must exceed said operational amplifier output voltage to permit said control switch to conduct thereby deenergizing said field winding such that as said DC generator output voltage falls below the power requirements of said operational amplifier causing its output to become negative, said DC generator output voltage exceeds said negative output of said operational amplifier by less than Zener voltage of said Zener diode.

Claim 15

A circuit for controlling the field excitation of a DC generator to regulate its output voltage, said circuit having an output providing an output voltage and a field winding, said circuit comprising means for sensing the output voltage level of said generator and providing an output voltage signal proportional thereto, reference voltage means for providing a reference voltage proportional to a predetermined generator output voltage, means for providing a periodic alternating waveform signal, static means for algebraically combining said generator output voltage signal and said periodic alternating waveform signal to provide an output signal comprising a periodic alternating waveform superimposed upon a direct current voltage level proportional to the output voltage of said generator so that, by comparison with said reference voltage, the level of said alternating waveform falls below the level of said reference voltage with a frequency corresponding to the frequency of said alternating waveform and for greater and lesser periods of time dependent upon the relative levels of said direct current voltage upon which it is superimposed and said reference voltage, an operational amplifier, a static power switch directly controlling current flow from the output of said controlled generator to said field winding, a static control switch connected to the output of said operational amplifier and connected in controlling relationship to said static power switch, said operational amplifier having an inverting and a noninverting input as said first and second inputs, respectively, and an output providing positive and negative square wave output signals when said inverting input level is less and more, respectively, than said noninverting input level, said control switch being responsive to the output of said operational amplifier whereby said control switch conducts when the output of said operational amplifier is negative and blocks when the output of said operational amplifier is positive, and said power switch being responsive to the state of said control switch whereby said power switch conducts excitation current to said field winding when said control switch blocks, and blocks excitation current to said field winding when said control switch conducts, said operational amplifier power requirements being provided from the output of said DC generator together with fail-safe means for insuring the continuous excitation of said DC generator in the event its output voltage falls below said operational amplifier requirements, said fail-safe means including a Zener diode having its anode connected to the output of said operational amplifier and its cathode to said control switch and the output of said DC generator whereby said Zener diode blocks and said DC generator output voltage turns off said control switch thereby turning on said power switch and supplying excitation current to said field winding when said operational amplifier output is positive, and, whereby said Zener diode conducts preventing said DC generator output voltage from turning off said power switch and preventing excitation current to flow to said winding when said operational amplifier output is negative and, whereby said Zener diode provides a fixed amount corresponding to its Zener voltage by which said DC generator output voltage must exceed said operational amplifier output voltage to permit said control switch to conduct thereby deenergizing said field winding such that as said DC generator output voltage falls below the power requirements of said operational amplifier causing its output to become negative, said DC generator output voltage exceeds said negative output of said operational amplifier by less than Zener voltage of said Zener diode.