AC to DC power converter with integrated line current control for improving power factor
First Claim
1. A power converter for converting alternating current at an input to direct current at an output comprisinga filter circuit coupled to the input comprising a series-connected choke coil and a parallel-connected capacitor,a full wave rectifier bridge coupled to the filter circuit for rectifying the filtered output of the filter circuit,a line current sensing circuit coupled to the full wave rectifier bridge for sensing the current waveform of line current output from the full wave rectifier bridge and for providing an output indicative of the sensed line current,an integrating circuit coupled to the line current sensing circuit for integrating the output of the line current sensing circuit and for providing a control signal output,a discharge circuit for the integrating circuit,a switching transistor circuit coupled to the full wave rectifier bridge for switching the output of the full wave rectifier bridge and for providing an output for powering a load, anda pulse width modulating circuit coupled to the control signal output of the integrating circuit and operated at a frequency much higher than the frequency of the alternating current input, the pulse width modulating circuit for driving the switching transistor circuit and the discharge circuit for the integrating circuit.
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Accused Products
Abstract
An AC to DC power converter comprises an input filter for filtering the alternating current input and an output filter for filtering and smoothing the direct current power output to a load. The output alternating current of the input filter is rectified and electronically switched at a frequency much higher than the frequency of the alternating line current input. The rectified line current is sensed and provided to an integrator circuit whose output provides one control signal input of a pulse width modulator circuit. The pulse width modulator circuit drives the electronic switching and at the same time, provides an output to a discharge circuit for discharging the integrator circuit.
135 Citations
7 Claims
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1. A power converter for converting alternating current at an input to direct current at an output comprising
a filter circuit coupled to the input comprising a series-connected choke coil and a parallel-connected capacitor, a full wave rectifier bridge coupled to the filter circuit for rectifying the filtered output of the filter circuit, a line current sensing circuit coupled to the full wave rectifier bridge for sensing the current waveform of line current output from the full wave rectifier bridge and for providing an output indicative of the sensed line current, an integrating circuit coupled to the line current sensing circuit for integrating the output of the line current sensing circuit and for providing a control signal output, a discharge circuit for the integrating circuit, a switching transistor circuit coupled to the full wave rectifier bridge for switching the output of the full wave rectifier bridge and for providing an output for powering a load, and a pulse width modulating circuit coupled to the control signal output of the integrating circuit and operated at a frequency much higher than the frequency of the alternating current input, the pulse width modulating circuit for driving the switching transistor circuit and the discharge circuit for the integrating circuit.
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6. A method of converting alternating line current at an input to direct current at an output of a power delivery circuit comprising the steps of
filtering the input alternating line current, rectifying the filtered line current and providing a rectified line current output, sensing the rectified line current output, integrating the sensed line current, providing an error control signal related to the desired waveform of the direct current output of the converter, controlling a switching of the line current responsive to the integration step and the error control signal at a frequency much higher than the frequency of the input alternating current, and discharging the integrated sensed line current simultaneously with the controlling of the line current switching, the integrated line current switching control maximizing the delivery of direct current to a load.
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7. A method of converting alternating line current at an input to direct current at an output of a power delivery circuit comprising the steps of
filtering the input alternating line current, rectifying the filtered line current and providing a rectified line current output, sensing the rectified line current output, integrating the sensed line current, providing an error control signal related to the desired waveform of the direct current output of the converter, controlling a switching of the line current responsive to the integration step and the error control signal at a frequency much higher than the frequency of the input alternating current, discharging the integrated sensing line current simultaneously with the controlling of the line current switching, sensing the output voltage delivered to the load and providing the error control signal by subtracting a predetermined reference voltage from the sensed output voltage, the integrated line current switching control maximizing the delivery of direct current to a load.
Specification