Power circuits for obtaining a high power factor electronically

Claim 2

A circuit for obtaining a high power factor electronically comprising a single phase solid state chopper circuit for energization by low frequency alternating-current sinusoidal line voltage and electronically shaped line current and comprising high frequency filter means for supplying sinusoidal voltage to a pair of supply terminals, and further comprising controlled switching means and coasting device means effectively coupled to said supply terminals and to coasting inductor means and operated to be conductive alternately to supply load current through said coasting inductor means to a load, current sensor means coupled to sense the instantaneous load current and produce a sensor signal indicative thereof, and a control circuit including generating means for generating a reference signal in phase with the line voltage and having a preselected waveshape and magnitude to determine the power level and to effect shaping of the line current by means of shaping the load current to obtain a high line power factor exceeding 90 percent, comparing means for instantaneously comparing said sensor and reference signals and producing an output signal, and circuit means actuated by said output signal for operating said controlled switching means at a variable high frequency chopping rate to force and shape the line current as the result of forcing and shaping the load current as determined by the preselected reference signal waveshape.

Claim 3

A circuit according to claim 1 wherein said generating means in said control circuit comprises means for deriving a sinusoidal control voltage in phase with the line voltage, and control function generator means for selectively varying the magnitude and waveshape of said sinusoidal control voltage according to a predetermined control function to derive the preselected reference signal waveshape, and said comparing means is comprised by a comparator circuit with hysteresis which derives a pair of control band limits closely adjacent to and conforming with the reference signal waveshape, said sensor signal being compared alternately with said reference signal control band limits to produce said output signal.

Claim 4

A solid state ballast for a gaseous discharge lamp comprising a single phase solid state chopper circuit for energization by low frequency alternating-current sinusoidal line voltage and electronically shaped line current and comprising rectifying means and high frequency filter means for supplying full wave rectified sinusoidal voltage to a pair of unidirectional voltage supply terminals, and further comprising controlled switching means and coasting device means effectively coupled to said unidirectional voltage supply terminals and to coasting inductor means and operated to be conductive alternately to supply load current through said coasting inductor means to a negative resistive characteristic gaseous discharge lamp, current sensor means coupled to sense the instantaneous load current and produce a sensor signal indicative thereof, and a control circuit comprising generating means for generating a reference signal in phase with the line voltage and having a preselected curved waveshape and magnitude to determine the power level and to effect shaping of the line current by means of shaping the load current to obtain a high line power factor exceeding 90 percent, comparing means for effectively comparing said sensor and reference signals and producing an output signal, and circuit means acTuated by said output signal for operating said controlled switching means at a variable high frequency chopping rate to force and shape the line current as a result of forcing and shaping the load current as determined by the curved reference signal waveshape.

Claim 5

A solid state ballast for a gaseous discharge lamp comprising a single phase solid state chopper circuit for energization by low frequency alternating-current sinusoidal line voltage and electronically shaped line current and comprising rectifying means and high frequency filter means for supplying full wave rectified sinusoidal voltage to a pair of unidirectional voltage supply terminals, and further comprising controlled switching means and coasting device means effectively coupled to said unidirectional voltage supply terminals and to coasting inductor means and operated to be conductive alternately to supply load current through said coasting inductor means to a negative resistive characteristic gaseous discharge lamp, current sensor means coupled to sense the instantaneous load current and produce a sensor signal indicative thereof, and a control circuit comprising generating means for generating a reference signal in phase with the line voltage and having a preselected curved waveshape and magnitude to determine the power level and to effect shaping of the line current by means of shaping the load current to obtain a high line power factor exceeding 90 percent, comparing means for effectively comparing said sensor and reference signals and producing an output signal, and circuit means acTuated by said output signal for operating said controlled switching means at a variable high frequency chopping rate to force and shape the line current as a result of forcing and shaping the load current as determined by the curved reference signal waveshape.

Claim 6

A solid state ballast according to claim 3 wherein said generating means in said control circuit comprises means for deriving a sinusoidal control voltage in phase with the line voltage and control function generator means for selectively electronically varying the magnitude and waveshape of said sinusoidal control voltage according to a predetermined control function to derive the curved reference signal waveshape, and said comparing means in said control circuit is comprised by a comparator circuit with hysteresis which derives a pair of control band limits closely adjacent to and conforming to the curved reference signal waveshape, said sensor signal being compared alternately with said reference signal control band limits to produce said output signal.

Claim 7

A solid state ballast for a gaseous discharge lamp comprising a single phase solid state chopper circuit for energization by low frequency alternating-current line voltage and electronically shaped line current and comprising full wave rectifying means and high frequency filter means for supplying rectified pulsating power voltage to a pair of unidirectional voltage supply terminals, and further comprising controlled switching means and coasting device means effectively coupled to said unidirectional voltage supply terminals and to coasting inductor means and operated to be conductive alternately to supply load current through said coasting inductor means to a gaseous discharge lamp, current sensor means coupled to sense the instantaneous load current and produce a sensor signal indicative thereof, and a control circuit comprising generating means for generating a reference signal in phase with the line voltage and having a preselected curved waveshape and magnitude to determine the power level and to effect shaping of the load current and therefore the line current to obtain a high line power factor exceeding 90 percent, comparing means for effectively comparing said sensor and reference signals and producing an output signal, and circuit means actuated by said output signal for operating said controlled switching means at a variable high frequency chopping rate to shape said load current as determined by the curved reference signal waveshape, wherein the alternating-current line voltage is sinusoidal, and said generating means in said control circuit is comprised by a transformer energized by the line voltage for deriving an approximately sinusoidal control voltage, and control function generator means for selectively electronically varying the magnitude and waveshape of said control voltage according to a predetermined control function to derive the curved reference signal waveshape, said control function generator means including a circuit for flattening said control voltage and an automatic gain control circuit so that the reference signal remains approximately constant despite variations in the line voltage.

Claim 8

A solid state ballast for a gaseous discharge lamp comprising a single phase solid state chopper circuit for energization by low frequency alternating-current line voltage and electronically shaped line current and comprising full wave rectifying means and high frequency filter means for supplying rectified pulsating power voltage to a pair of unidirectional voltage supply terminals, and further comprising controlled switching means and coasting device means effectively coupled to said unidirectional voltage supply terminals and to coasting inductor means and operated to be conductive alternately to supply load current through said coasting inductor means to a gaseous discharge lamp, current sensor means coupled to sense the instantaneous load current and produce a sensor signal indicative thereof, and a control circuit comprising generating means for generating a reference signal in phase with the line voltage and having a preselected curved waveshape and magnitude to determine the power level and to effect shaping of the load current and therefore the line current to obtain a high line power factor exceeding 90 percent, comparing means for effectively comparing said sensor and reference signals and producing an output signal, and circuit means actuated by said output signal for operating said controlled switching means at a variable high frequency chopping rate to shape said load current as determined by the curved reference signal waveshape, wherein the alternating-current line voltage is sinusoidal, and said generating means in said control circuit is comprised by a transformer energized by the line voltage for deriving an approximately sinusoidal control voltage, and control function generator means for selectively electronically varying the magnitude and waveshape of said control voltage according to a predetermined control function to derive the curved reference signal waveshape, said control function generator means including a circuit for flattening said control voltage and an automatic gain control circuit so that the reference signal remains approximately constant despite variations in the line voltage.

Claim 9

A solid state ballast according to claim 5 wherein said controlled switching means is comprised by a power transistor, and said circuit means actuated by said output signal for operating said controlled switching means at a variable high frequency chopping rate is energized by said transformer and includes alternately operative positive and negative base drive circuits for respectively supplying variable base current for rendering said power transistor conductive and nonconductive.