AC to DC power converter and method with integrated line current control for improving power factor
First Claim
1. A power converter for converting alternating line current provided at an input to direct current delivered at an output of the power converter comprisingfiltering means for filtering the input alternating line current,rectifying means responsive to the input current filtering means for rectifying the filtered input line current,direct current control means, operated at a substantially higher frequency than the frequency of the input alternating line current, for controlling the direct current delivered to the output of the power converter, the direct current control means particularly comprising current switching means for switching the filtered and rectified line current at high frequency and a control circuit for providing a control signal output for controlling the current switching means and an integrating means,line current sensing means, responsive to an output of the current rectifying means, for sensing the filtered and rectified line current andthe integrating means responsive to the line current sensing means and to the control signal output of the control circuit of the direct current control means for integrating the sensed line current and for providing a first control signal input to the control circuit of the direct current control means.
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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 an at the same time, provides an output to a discharge circuit for discharging the integrator circuit.
99 Citations
10 Claims
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1. A power converter for converting alternating line current provided at an input to direct current delivered at an output of the power converter comprising
filtering means for filtering the input alternating line current, rectifying means responsive to the input current filtering means for rectifying the filtered input line current, direct current control means, operated at a substantially higher frequency than the frequency of the input alternating line current, for controlling the direct current delivered to the output of the power converter, the direct current control means particularly comprising current switching means for switching the filtered and rectified line current at high frequency and a control circuit for providing a control signal output for controlling the current switching means and an integrating means, line current sensing means, responsive to an output of the current rectifying means, for sensing the filtered and rectified line current and the integrating means responsive to the line current sensing means and to the control signal output of the control circuit of the direct current control means for integrating the sensed line current and for providing a first control signal input to the control circuit of the direct current control means.
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8. A method of converting alternating line current provided at an input to direct current delivered at an output of a power converter circuit comprising the steps of
filtering the input alternating line current, rectifying the filtered line current and providing a rectified line current output, switching the rectified line current output at a rate much higher than the frequency of the input alternating line current, sensing the rectified line current output, integrating the sensed line current to provide a first control signal, providing an error control signal related to the desired waveform of the direct current output of the power converter,and controlling the switching of the rectified line current output and simultaneously discharging the integrated line current, the line current switching control step being responsive to the first control signal of the line current integration step and to the error control signal.
Specification