Switching power converter with magnetizing current shaping
First Claim
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1. A method, comprisingrectifying an AC input voltage to produce a rectified input voltage;
- determining a desired peak current through a power factor control (PFC) feedback loop;
setting a peak current threshold to equal a first threshold value prior to a zero crossing time for the AC input voltage and to equal a second threshold value after the zero crossing time, wherein the first threshold value is less than the second threshold value; and
cycling a power switch so that power switch conducts a magnetizing current equaling the desired peak current when the desired peak current exceeds the peak current threshold and so that the power switch conducts a magnetizing current equaling the peak current threshold when the desired peak current is less than the peak current threshold.
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Abstract
A switching power converter is provided that uses at least two peak current thresholds. In particular, the switching power converter clamps a desired peak current to not fall below a low peak current threshold value while a rectified input voltage is decreasing and to not fall below a high peak current threshold value subsequent to zero crossing times for an AC input voltage.
12 Citations
20 Claims
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1. A method, comprising
rectifying an AC input voltage to produce a rectified input voltage; -
determining a desired peak current through a power factor control (PFC) feedback loop; setting a peak current threshold to equal a first threshold value prior to a zero crossing time for the AC input voltage and to equal a second threshold value after the zero crossing time, wherein the first threshold value is less than the second threshold value; and cycling a power switch so that power switch conducts a magnetizing current equaling the desired peak current when the desired peak current exceeds the peak current threshold and so that the power switch conducts a magnetizing current equaling the peak current threshold when the desired peak current is less than the peak current threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A switching power converter, comprising:
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a power switch; a dimmer configured to apply a phase cut dimming to an AC input voltage responsive to a dimming command to produce a processed AC input voltage; a dimmer detection circuit configured to determine whether the dimmer applied the phase cut dimming to the processed AC input voltage; a controller including a power factor control (PFC) feedback loop configured to determine a desired peak current responsive to a determination by the dimmer detection circuit that the dimmer applied the phase cut dimming, and wherein, prior to a zero crossing time for the AC input voltage, the controller is further configured to cycle the power switch to conduct a first magnetizing current equaling the desired peak current while the desired peak current is greater than a first threshold and to clamp the first magnetizing current to equal the first threshold while the desired peak current is less than the first threshold, and wherein, subsequent to the zero crossing time for the AC input voltage, the controller is further configured to cycle the power switch to conduct a second magnetizing current equaling the desired peak current while the desired peak current is greater than a second threshold and to clamp the second magnetizing current to equal the second threshold while the desired peak current is less than the second threshold, wherein the second threshold is greater than the first threshold. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification