Charging and balancing batteries

A battery charging system comprising:

• a stacked half bridge rectifier having an upper half bridge and a lower half bridge;
• a blocking capacitor and a winding coupled between a midpoint of the upper half bridge and a midpoint of the lower half bridge;
• a battery coupled between an upper terminal of the upper half bridge and a lower terminal of the lower half bridge;
• and
• control circuitry that selectively operates the stacked half bridge rectifier as a switched capacitor converter using the blocking capacitor as a flying capacitor by alternating between:
• a first switching state in which lower switches of the upper and lower half bridges of the rectifier are closed while upper switches of the upper and lower half bridges are opened;
• and
• a second switching state in which upper switches of the upper and lower half bridges of the rectifier are closed;
• wherein the battery further comprises first and second series-connected batteries having a midpoint coupled to a midpoint of the stacked half bridge rectifier, and the switched capacitor converter operates as a balancer to equalize charge between the first and second series-connected batteries.

A power converter comprising:

• a stacked half bridge converter having an upper half bridge and a lower half bridge;
• a capacitor and an inductance coupled between a switch node of the upper half bridge and a switch node of the lower half bridge;
• a first output coupled across the upper half bridge and a second output coupled across the lower half bridge;
• and
• control circuitry that selectively operates the stacked half bridge converter as:
• a rectifier to produce output DC voltages from an input AC voltage received via the capacitor and inductance;
• or
• a switched capacitor converter using the capacitor as a flying capacitor to balance the output DC voltages by alternating between:
• a first switching state in which lower switches of the upper and lower half bridges of the converter are closed while upper switches of the upper and lower half bridges of the converter are opened;
• and
• a second switching state in which upper switches of the upper and lower half bridges of the converter are closed;
• wherein the switched capacitor converter operates as a booster to charge the battery from a DC voltage source having a voltage lower than a voltage of the battery.