Efficient Regulation of Capacitance Voltage(s) in a Switched Mode Multilevel Power Converter

A method of regulating a multilevel power converter comprising a first capacitor connected in parallel with a plurality of power switches serially connected between a top power switch and a bottom power switch, and an inductor connected between an output node and a midpoint node connected at a midpoint of the plurality of power switches, the multilevel power converter having a number of levels greater than or equal to three, the method comprising:

• performing one of a first comparison and a second comparison, said first comparison comparing a first voltage and a top voltage associated with the top power switch, and said second comparison comparing a second voltage and a bottom voltage associated with the bottom power switch;
• indirectly measuring a direction of a current through the inductor based on one of the first and second comparisons;
• and
• detecting a first capacitor voltage across the first capacitor;
• generating a first logic signal based on a comparison between the first capacitor voltage and a first reference voltage;
• and
• selecting an operating state of the multilevel power converter to regulate the first capacitor voltage across the first capacitor and to generate a target voltage level at the midpoint node based on the indirectly measured direction of the inductor current, the first logic signal, and an input command signal.

A power conversion circuit comprising:

• a multilevel power converter comprising a first capacitor connected in parallel with a plurality of power switches serially connected between a top power switch and a bottom power switch, and an inductor connected between an output node and a midpoint node connected at a midpoint of the plurality of power switches, the multilevel power converter having three or more levels;
• a current detection circuit configured to indirectly measure a direction of a current through an inductor connected between the midpoint node and the output node based on one of a comparison between a battery voltage and a top voltage associated with the top power switch and a comparison between a ground voltage and a bottom voltage associated with the bottom power switch;
• a first capacitor voltage detection circuit connected in parallel with the first capacitor and configured to detect a first capacitor voltage across the first capacitor and to generate a first logic signal based on a comparison between the first capacitor voltage and a first reference voltage;
• and
• a control circuit connected to an input of each of the power switches, the control circuit configured to control the power switches based on the indirectly measured direction of the inductor current, the first logic signal, and an input command signal to regulate a first capacitor voltage across the first capacitor and to generate a target voltage level at the midpoint node.

A power conversion circuit comprising:

• a multilevel power converter comprising a capacitor connected in parallel with two middle power switches serially connected between a top power switch and a bottom power switch, and an inductor connected between an output node and a midpoint node connected at a midpoint between the two middle power switches;
• a current detection circuit configured to indirectly measure a direction of a current through the inductor based on one of a comparison between a first voltage and a midpoint voltage associated with the midpoint node and a comparison between a second voltage and the midpoint voltage;
• a capacitor voltage detection circuit connected in parallel with the capacitor and configured to detect a capacitor voltage across the capacitor and to generate a logic signal based on a comparison between the capacitor voltage and a reference voltage;
• and
• a control circuit connected to an input of each of the power switches, the control circuit configured to select an operating state of the multilevel power converter to regulate the capacitor voltage across the capacitor and to generate a target midpoint voltage at the midpoint node based on the indirectly measured direction of the inductor current, the logic signal, and an input command signal.

A method of regulating a multilevel power converter comprising a capacitor connected in parallel with two middle power switches serially connected between a top power switch and a bottom power switch, and an inductor connected between an output node and a midpoint node connected at a midpoint of the middle power switches, the method comprising:

• performing one of a first comparison and a second comparison, said first comparison comparing a first voltage and a midpoint voltage associated with the midpoint node, and said second comparison comparing a second voltage and the midpoint voltage;
• indirectly measuring a direction of a current through the inductor based on one of the first and second comparisons;
• and
• detecting a capacitor voltage across the capacitor;
• generating a logic signal based on a comparison between the capacitor voltage and a reference voltage;
• and
• selecting an operating state of the multilevel power converter to regulate the capacitor voltage across the capacitor and to generate a target midpoint voltage at the midpoint node based on the indirectly measured direction of the inductor current, the logic signal, and an input command signal.