Digital average input current control in power converter
First Claim
1. A method, comprising:
- sampling an inductor current of an inductor of a converter;
sampling an input voltage of the converter;
sampling an output voltage of the converter;
predicting, by a controller, the inductor current based on the sampled inductor current, the sampled input voltage, and the sampled output voltage;
controlling a duty cycle based on the predicted inductor current to cause an input current of the converter to approach a desired input current; and
transferring the converter from an alternating buck-boost mode to a buck mode or a boost mode in response to the duty cycle dropping below or climbing above a threshold for at least a predetermined number of cycles.
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Abstract
A digital average-input current-mode control loop for a DC/DC power converter. The power converter may be, for example, a buck converter, boost converter, or cascaded buck-boost converter. The purpose of the proposed control loop is to set the average converter input current to the requested current. Controlling the average input current can be relevant for various applications such as power factor correction (PFC), photovoltaic converters, and more. The method is based on predicting the inductor current based on measuring the input voltage, the output voltage, and the inductor current. A fast cycle-by-cycle control loop may be implemented. The conversion method is described for three different modes. For each mode a different control loop is used to control the average input current, and the control loop for each of the different modes is described. Finally, the algorithm for switching between the modes is disclosed.
975 Citations
20 Claims
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1. A method, comprising:
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sampling an inductor current of an inductor of a converter; sampling an input voltage of the converter; sampling an output voltage of the converter; predicting, by a controller, the inductor current based on the sampled inductor current, the sampled input voltage, and the sampled output voltage; controlling a duty cycle based on the predicted inductor current to cause an input current of the converter to approach a desired input current; and transferring the converter from an alternating buck-boost mode to a buck mode or a boost mode in response to the duty cycle dropping below or climbing above a threshold for at least a predetermined number of cycles. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus, comprising:
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a circuit configured to; sample an inductor current of an inductor of a converter; sample an input voltage of the converter; and sample an output voltage of the converter; and a controller configured to; predict the inductor current based on the sampled inductor current, the sampled input voltage, and the sampled output voltage; control a duty cycle based on the predicted inductor current to cause an input current of the converter to approach a desired input current; and transfer the converter from an alternating buck-boost mode to a buck mode or a boost mode in response to the duty cycle dropping below or climbing above a threshold for at least a predetermined number of cycles. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method, comprising:
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predicting, by a controller, an inductor current of an inductor of a converter; controlling a duty cycle based on the predicted inductor current to cause an input current of the converter to approach a desired input current; and transferring the converter from an alternating buck-boost mode to a buck mode or a boost mode in response to the duty cycle dropping below or climbing above a threshold for at least a predetermined number of cycles. - View Dependent Claims (17, 18, 19, 20)
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Specification