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US 8,912,770 B2Granted
Power conversion feedback control circuit for reaching a goal voltage
AssigneeAtmel Corporation
InventorsCharles Cai, Jeff Kotowski, Kien Vi
Life of this patent
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Abstract
A power conversion circuit of two feedback loops is disclosed that includes a feedback control circuit for ramping up or down a commanded voltage to a load (e.g., LEDs). The second feedback loop feeds into the first feedback loop, and the second feedback loop operates at a slower bandwidth than the first feedback loop. When ramping up or down the commanded voltage, a voltage overshoot results because of delay in the system. The overshoot can be compensated for by a final adjustment to the commanded voltage.
Claims16
A power conversion circuit comprising:
- a power converter comprising a power input coupled to a power source, an output coupled to a load, and a control input, wherein the power converter is configured to convert an input voltage on the power input to an output voltage on the output based on the control input;
- a first feedback circuit coupled between the output of the power converter and the control input of the power converter, wherein the first feedback circuit is configured to operate at a first bandwidth;
- a second feedback circuit coupled between the load and the first feedback circuit, wherein the second feedback circuit is configured to operate at a second bandwidth slower than the first bandwidth, and wherein the second feedback circuit is configured to change a commanded voltage to the first feedback circuit at a fixed ramp rate until a detected voltage at the load crosses a goal voltage and overshoots the commanded voltage, and after the detected voltage crosses the goal voltage and overshoots the commanded voltage, decrease or increase the commanded voltage by an overshoot compensation amount to cause the detected voltage to reach the goal voltage at a rate different than the fixed ramp rate.
A method performed by a feedback control circuit for a second feedback circuit, the method comprising:
- setting a commanded voltage on a commanded output to an initial value, the commanded output being coupled to a first feedback circuit, the first feedback circuit being coupled to a power converter, the power converter being coupled to a load;
- changing the commanded voltage at a fixed ramp rate;
- detecting a detected voltage on a detection input coupled to the load;
- changing the commanded voltage at the fixed ramp rate until the detected voltage crosses a goal voltage, wherein the fixed ramp rate is selected so that the detected voltage overshoots the commanded voltage by an amount within a range;
- and
- after the detected voltage crosses the goal voltage and overshoots the commanded voltage, decreasing or increasing the commanded voltage by an overshoot compensation amount to cause the detected voltage to reach the goal voltage at a rate different than the fixed ramp rate.
3 more elements
A feedback control circuit comprising:
- a detection input and a commanded output, the detection input being configured for coupling to a load and the commanded output being configured for coupling to a first feedback circuit;
- and
- a digital logic circuit configured to perform operations comprising:
- setting a commanded voltage on the commanded output to an initial value, the commanded output being coupled to the first feedback circuit, the first feedback circuit being coupled to a power converter, the power converter being coupled to the load;
- changing the commanded voltage at a fixed ramp rate;
- detecting a detected voltage on the detection input coupled to the load;
- changing the commanded voltage at the fixed ramp rate until the detected voltage crosses a goal voltage, wherein the fixed ramp rate is selected so that the detected voltage overshoots the commanded voltage;
- and
- after the detected voltage crosses the goal voltage and overshoots the commanded voltage, decreasing or increasing the commanded voltage by an overshoot compensation amount to cause the detected voltage to reach the goal voltage at a rate different than the fixed ramp rate.
6 more elements
Dependencies are inferred from the claim text.