Voltage balancing circuit and method for series connected devices

A method of operating a converter, the converter comprising:

• a first-stage bus comprising a first first-stage node and a second first-stage node;
• a switch unit comprising:
• a first high-side switch, a second high-side switch, a first low-side switch, and a second low-side switch connected in series between the first first-stage node and the second first-stage node;
• and
• an output node defined between the first high-side switch and the first low-side switch;
• a first stage comprising:
• a first-stage voltage divider connected between the first first-stage node and the second first-stage node, the first stage voltage divider comprising:
• a first first-stage voltage divider capacitor and a second first-stage voltage divider capacitor connected in series and defining a first voltage divider node between the first first-stage voltage divider capacitor and the second first-stage voltage divider capacitor;
• a first-stage balancing capacitor connected in parallel to the first high-side switch and the first low-side switch;
• and
• a first-stage balancing unit comprising:
• a first-stage high-side switch and a first-stage low-side switch connected in series via a first-stage balancing unit node, wherein
• the first-stage balancing unit node is coupled to the first-stage voltage divider node, and
• the first-stage balancing unit is connected in parallel to the first-stage balancing capacitor;
• and
• a controller configured to control the switches of the converter;
• and
• the method comprising:
• setting a first converter state by:
• switching on the first high-side switch and the second high-side switch,
• switching off the first low-side switch and the second low-side switch;
• and
• switching on the first-stage low-side switch, and
• setting a second converter state by:
• switching on the first low-side switch and the second low-side switch,
• switching off the first high-side switch and the second high-side switch, and
• switching on the first-stage high-side switch.

A non-transitory computer-readable medium for operating a converter, the converter comprising:

• a first-stage bus comprising a first first-stage node and a second first-stage node;
• a switch unit comprising:
• a first high-side switch, a second high-side switch, a first low-side switch, and a second low-side switch connected in series between the first first-stage node and the second first-stage node;
• and
• an output node defined between the first high-side switch and the first low-side switch;
• a first stage comprising:
• a first-stage voltage divider connected between the first first-stage node and the second first-stage node, the first stage voltage divider comprising:
• a first first-stage voltage divider capacitor and a second first-stage voltage divider capacitor connected in series and defining a first voltage divider node between the first first-stage voltage divider capacitor and the second first-stage voltage divider capacitor;
• a first-stage balancing capacitor connected in parallel to the first high-side switch and the first low-side switch;
• and
• a first-stage balancing unit comprising:
• a first-stage high-side switch and a first-stage low-side switch connected in series via a first-stage balancing unit node, wherein
• the first-stage balancing unit node is coupled to the first-stage voltage divider node, and
• the first-stage balancing unit is connected in parallel to the first-stage balancing capacitor;
• and
• a controller configured to control the switches of the converter, and
• wherein the non-transitory computer-readable medium comprises programmed instructions which, when executed by at least one processor of the converter, are configured to:
• set a first converter state, wherein the programmed instructions, when executed by the at least one processor, in order to set the first converter state, are further configured to:
• switch on the first high-side switch and the second high-side switch,
• switch off the first low-side switch and the second low-side switch;
• and
• switch on the first-stage low-side switch, and
• set a second converter state, wherein the programmed instructions, when executed by the at least one processor, in order to set the second converter state, are further configured to:
• switch on the first low-side switch and the second low-side switch,
• switch off the first high-side switch and the second high-side switch, and
• switch on the first-stage high-side switch.