High speed power factor controller
First Claim
1. A power factor correction system, comprising:
- a voltage sensor having an input coupled across a first and second power line;
a current sensor having an input coupled to one of said first and second power lines;
a digital microprocessor;
circuitry for coupling signals from said voltage sensor to said microprocessor;
circuitry for coupling signals from said current sensor to said microprocessor;
said microprocessor including programming means for determining a phase difference between a sensed voltage and a sensed current, and providing first, second, third and fourth switching outputs responsive to said phase difference;
a transformer having a first winding and a second winding;
a first and second capacitor;
a first switching device having an input coupled to said first switching output and having a first output coupled in series with said first winding forming a first switching path, said first switching path being disposed across said power lines;
a second switching device having an input coupled to said second switching output and having a second output coupled in series with said first winding forming a second switching path, said second switching path being disposed across said power lines;
a third switching device having an input coupled to said third switching output and having a third output coupled in series with said first capacitor and said second winding forming a third switching path; and
a fourth switching device having an input coupled to said fourth switching output and having a fourth output coupled in series with said second capacitor and said second winding forming a fourth switching path;
wherein a power factor associated with said first and second power lines is corrected by selectively switching energy between magnetic and electric forms in said capacitors and said windings.
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Accused Products
Abstract
A microprocessor is coupled to sense the current and voltage in a power phase at a high sampling rate such as two hundred fifty-five (255) times per cycle, and to determine the power factor. The primary of a transformer is coupled across the power lines, and at least two capacitors, forming separate switching paths, are coupled to the secondary of the transformer. High speed switching circuitry under the control of the microprocessor alternately charges and discharges the capacitors, at varying frequencies, to alternately store energy from the power lines when the variable load is returning energy to the power lines, and to supply the stored energy back to the power lines when the variable load is absorbing energy from the power lines. This corrects the power factor since the frequency of the high speed switching circuitry is varied with the varying reactance of the load.
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Citations
25 Claims
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1. A power factor correction system, comprising:
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a voltage sensor having an input coupled across a first and second power line; a current sensor having an input coupled to one of said first and second power lines; a digital microprocessor; circuitry for coupling signals from said voltage sensor to said microprocessor; circuitry for coupling signals from said current sensor to said microprocessor; said microprocessor including programming means for determining a phase difference between a sensed voltage and a sensed current, and providing first, second, third and fourth switching outputs responsive to said phase difference; a transformer having a first winding and a second winding; a first and second capacitor; a first switching device having an input coupled to said first switching output and having a first output coupled in series with said first winding forming a first switching path, said first switching path being disposed across said power lines; a second switching device having an input coupled to said second switching output and having a second output coupled in series with said first winding forming a second switching path, said second switching path being disposed across said power lines;
a third switching device having an input coupled to said third switching output and having a third output coupled in series with said first capacitor and said second winding forming a third switching path; anda fourth switching device having an input coupled to said fourth switching output and having a fourth output coupled in series with said second capacitor and said second winding forming a fourth switching path; wherein a power factor associated with said first and second power lines is corrected by selectively switching energy between magnetic and electric forms in said capacitors and said windings. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A power factor correction system, comprising:
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a transformer having a first winding and a second winding; a plurality of capacitors; a first plurality of switching devices, responsive to switching pulses, coupling said capacitors across said second winding; a second plurality of switching devices, responsive to switching pulses, coupling said first winding across first and second power lines; and means for correcting the power factor associated with said power lines by switching energy between magnetic and electric fields in said capacitors and said windings. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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18. A power factor correction system comprising:
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at least one voltage sensor coupled to power lines; at least one current sensor coupled to said power lines; at least one analog to digital converter having an input coupled to respective outputs of said voltage sensor and said current sensor; digital processing circuitry, coupled to an output of said analog to digital converter; a first winding and a second winding being magnetically coupled; first and second capacitors; first and second resistors; first, second, third and fourth rectifiers; and first, second, third and fourth switching devices; said first winding coupled in series with said first rectifier, said first resistor, and an output of said first switching device, across said power lines; said first winding coupled in series with said second rectifier, said first resistor, and an output of said second switching device, across said power lines; said second winding coupled in series with said third rectifier, said second resistor, said first capacitor, and an output of said third switching device; said second winding coupled in series with said fourth rectifier, said second resistor, said second capacitor, and an output of said fourth switching device; said digital processing circuitry calculating a phase difference between a voltage and a current on said power lines and an operative switching quadrant, and for responsively pulsing the inputs to said first, second, third and fourth switching devices; said switching devices, in response to said pulses, alternately storing excess energy from said power lines in said capacitors and returning stored energy from said capacitors to said power lines. - View Dependent Claims (19, 20)
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21. A power factor correction system comprising:
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a microprocessor coupled to voltage sense circuitry and current sense circuitry; said voltage and current sense circuitry coupled to power lines; a primary of a transformer coupled to said power lines; at least two capacitors coupled to a secondary of said transformer, forming separate switching paths; switching circuitry coupled to said microprocessor, to said primary, and to said capacitors; said microprocessor determining a phase difference between a sensed voltage and a sensed current and responsively controlling said switching circuitry, alternately storing energy from said power lines in said capacitors and discharging energy from said capacitors to said power lines, correcting a power factor associated with said power lines. - View Dependent Claims (22, 23, 24, 25)
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Specification