Voltage regulator for alternating current lighting system

Abstract

A semi-conductor voltage regulator includes a dual transistor differential amplifier pair adapted to so as not to be damaged by reverse voltages during the application of either polarity of alternating current to the associated sensing network. The sensing network includes resistors, the value of which are selected to provide an offset current during one polarity of alternating current with respect to the other polarity. A diode is coupled with the differential amplifier transistor pair in order to protect those devices and the load from high, suddenly-applied or transient voltages generated externally or by internal switching within the regulator.

What is claimed is: 
     
       1. In a lighting system for use with an AC power producing source the frequency voltage, amplitude and waveform of which vary from time to time and having lighting means connected to be energized by the AC power supplied from said source: a voltage sensitive network having terminals connected to be energized by the waveform of said source and having output terminals producing a signal dependent upon the true RMS voltage value of said source;   control means connected to control the flow of AC power from said source to said lighting means and having an input means;   two amplifying means each having an input terminal, an output terminal, and a common input-output terminal, the common input-output terminals of said amplifying means being connected together, the output terminal of one amplifying means supplying power to said input terminals of said control means;   said input terminals of said two amplifying means being connected to said output terminals of said true RMS voltage sensitive network to regulate the AC power supplied by said source to said lighting means;   impedance means for preventing destructive voltages and currents from appearing between said input terminals and said common input-output terminals of said amplifying means for either polarity of the waveform applied to said network to prevent the true RMS voltage supplied from said source to said lighting means from rising above a preselected value; and   means to make said network slightly more sensitive to one polarity portion of the waveform of said source than to the other polarity portion.   
     
     
       2. A system for supplying AC power from a source to a lighting means, comprising: a control means for varying the flow of AC power from said source to said lighting means;   a network sensitive to a true RMS voltage applied thereto and having an output, said network energized by the waveform of said source;   means to make said network slightly more sensitive to one polarity portion of the waveform of said source than to the other polarity portion;   means connecting the output of said network to said control means to regulate the AC power supplied by said source to said lighting means.   
     
     
       3. An AC vehicular power system including an engine-driven alternator and a lighting load to be energized therefrom; a control means with an input means capable of limiting the AC voltage supplied from said alternator to said load in response to a signal at its input means;   a first true RMS voltage sensitive network energized by the waveform of said alternator and having a time constant longer than the period of the voltage produced by said alternator and having an output;   a second voltage sensitive network having a time constant shorter than the period of the voltage produced by said alternator and therefore primarily sensitive to peak voltages, and having an output;   means connecting said outputs of both said networks to the input of said control means to prevent the voltage of said system from exceeding predetermined voltages for longer than predetermined times; and   means to make said network slightly more sensitive to one polarity portion of the waveform of said alternator than to the other polarity portion.   
     
     
       4. A system for supplying AC power from an engine-driven alternator source, the voltage, frequency, and waveform of which vary from time to time to a lamp load; including a true RMS regulator;   said regulator containing a semi-conductor switching means connected to control the flow of power from said source to said load and having a gate terminal means;   a true RMS voltage sensitive network energized by the waveform of said alternator source and having terminals connected to said source and having output terminals;   a control signal path for connecting said output of said network to said gate, said path containing a semiconductor junction biased and connected so that the forward voltage drop thereof cancels with a similar drop inherent in other components of said regulator at the time when a gate signal is required to produce a stable RMS voltage to said load, whereby said regulator regulates the AC power supplied by said alternator source to said lamp load; and   means for making said network slightly more sensitive to one polarity portion of the waveform of said alternator source than to the other polarity portion.   
     
     
       5. In a lighting system for use with an AC power producing source the frequency voltage, amplitude and waveform of which vary from time to time and having lighting means connected to be energized by the AC power supplied from said source: a true RMS voltage sensitive network having terminals connected to be energized by the waveform of said source and having output terminals producing a signal dependent upon the RMS value of said source;   control means connected to control the flow of power from said source to said lighting means and having an input means;   two amplifying means each having an input terminal, an output terminal, and a common input-output terminal, the common input-output terminals of said amplifying means being connected together, the output terminal of one amplifying means supplying power to said input terminal of said control means;   said input terminals of said amplifying means being connected to said output terminals of said true RMS voltage sensitive network;   impedance means to prevent destructive voltages and currents from appearing between said input terminals and said common input-output terminals of said amplifying means for either polarity of the waveform applied to said network to prevent the true RMS voltage supplied from said source to said lighting means from rising above a preselected value, to thereby regulate the AC power supplied by said source of said lighting means; and   means for making said network slightly more sensitive to one polarity portion of the waveform of said source than to the other polarity portion.   
     
     
       6. The system of claim 5 wherein said source is an alternator attached to an engine of a vehicle. 
     
     
       7. The system of claim 6 wherein said amplifying means are transistors with their emitters connected together. 
     
     
       8. The system of claim 6 wherein said network contains a lamp with an impedance which varies with the power applied thereto. 
     
     
       9. The system of claim 8 wherein said source is an alternator attached to an engine of a vehicle and said lighting means are lamps associated with said vehicle. .Iadd. 10. In a lighting system for use with an AC power producing source, the frequency, voltage, amplitude and waveform which vary from time to time, and having lighting means connected thereto to be energized by the AC power supplied from said source: a voltage sensitive network having input terminals for being energized by the AC waveform of said source and having output terminals for producing a signal dependent upon the true RMS voltage value of said source;   control means for controlling the flow of AC power from said source to said lighting means, said control means operating responsive to a control signal at an input thereto;   two three-port amplifying means, each having an input terminal, an output terminal and a common input-output terminal, with said common input-output terminals of said three-port amplifying means being coupled together, said output terminal of one three-port amplifying means supplying said control signal to said input control means;   impedance means for preventing destructive reverse bias voltages and currents from appearing between said input terminals and said common input-output terminals of each of said three-port amplifying means from the AC waveform applied to said voltage sensitive network; and   said input terminals of each of said three-port amplifying means being coupled to said output terminals of said voltage sensitive network for operating said control means for preventing the true RMS voltage supplied from said AC power source to said lighting means from rising above a preselected value. .Iaddend. .Iadd. 11. The AC power regulator as described in claim 10 wherein said source is an alternator attached to an engine of a vehicle. .Iaddend. .Iadd. 12. The AC power regulator as described in claim 11 wherein said three-port amplifying means are transistors having emitters coupled together in a common emitter circuit. .Iaddend..Iadd. 13. The AC power regulator as described in claim 11 wherein said network contains a lamp having an impedance which varies with the power applied thereto. .Iaddend..Iadd. 14. The AC power regulator as described in claim 13 wherein said lamp has an incandescent filament having a resistance which increases with the power applied thereto. .Iaddend..Iadd. 15. The AC power regulator as described in claim 13 wherein said impedance means is a diode and said control means is a silicon controlled rectifier. .Iaddend. .Iadd. 16. In a lighting system for use with an AC power producing source the frequency, voltage, amplitude and waveform of which vary from time to time, said AC source being coupled to lighting means for being energized thereby, said lighting system comprising:   a true RMS voltage sensitive network having terminals connected to be energized by the AC waveform of said source and having output terminals for producing a signal dependent upon the true RMS value of the voltage from said source;   control means for controlling the flow of power from said source to said lighting means, said control means having an input thereto;   two amplifying means each having an input terminal, an output terminal and a common input-output terminal, said common input-output terminals of said amplifying means being coupled together, said output terminal of one of said amplifying means supplying power to said input of said control means, said input terminals of said amplifying means being coupled to said output terminals of said true RMS voltage sensitive network;   impedance means for bypassing destructive voltages and currents from between said input terminals and said common input-output terminals of said amplifying means from the AC waveform applied to said network, thereby preventing the RMS voltage supplied from said source to said lighting means from exceeding a predetermined value. .Iaddend. .Iadd. 17. An AC voltage regulator for use in regulating the RMS power supplied to a load from an AC voltage source, said AC voltage regulator comprising:   control means having a variable impedance for controlling the instantaneous voltage from said AC voltage source to said load, said control means operating responsive to signals to an input terminal thereof;   a first network for producing across output terminals thereof an output signal responsive to the RMS AC voltage from said AC voltage source to said load;   a first and a second amplifier each having an input terminal, an output terminal and a common input-output terminal, said common input-output terminals coupled together at a first junction point, with said first and second amplifiers coupled to said AC voltage source for receiving AC power therefrom, with said input terminals of said first and second amplifiers coupled to said output terminals of said first network, and with said output terminal of at least one of said first and second amplifiers coupled to said input terminal of said control means for regulating the RMS power supplied to said load;   a resistance interposed between a first terminal of said AC voltage source and said first junction point; and   a rectifying device interposed between said first junction point and a second terminal of said AC voltage source for conducting current therethrough when the AC voltage between said first and second terminals of said AC voltage source reverse biases said first and second amplifiers into a generally non-amplifying mode. .Iaddend..Iadd. 18. The AC voltage regulator as described in claim 17 wherein said control means is coupled across said first and second terminals of said AC voltage supply as a shunt regulator. .Iaddend. .Iadd. 19. The AC voltage regulator as described in claim 18 wherein said control means is a silicon controlled rectifier. .Iaddend..Iadd. 20. The AC voltage regulator as described in claim 18 wherein said first network comprises a balance bridge network having a first and a second leg coupled in parallel between said first and second terminals of said AC voltage source, said first leg having elements therein for responding to the instantaneous voltage from said AC voltage source, and said second leg having elements therein for responding to the AC RMS voltage from said AC voltage source. .Iaddend..Iadd. 21. The AC voltage regulator as described in claim 20 wherein one of said elements in said second leg of said bridge network comprises an incandescent filament of a light emitting device of a type having a thermal time constant greater than the frequency of the AC voltage source.