Methods and apparatus for a cascade converter using series resonant cells with zero voltage switching

A method of balancing the voltage between first and second series resonant converter (SRC) cells connected in series to a common high voltage (HV) input, where the first and second SRC cells are configured such that they do not share the same load, the method comprising:

• sensing at least one variable signal from the first SRC cell, wherein the variable signal comprises at least one signal selected from the group consisting of input voltage, input current, output voltage, and output current;
• based on the value of the sensed variable signal, activating at least one respective AC/DC converter coupled to the output of the first respective SRC cell;
• coupling the output of the first activated AC/DC converter associated with the first SRC cell so as to increase the power at a DC output of the second SRC cell;
• and
• changing the input voltage value of at least one of the first and second SRC cells so as to restore the input voltage balance between the first and second SRC cells.

A voltage balancing circuit, comprising:

• a first series resonant converter (SRC) cell, the first SRC cell comprising an input, a DC output, and a first AC/DC converter connected in parallel with the input of the first SRC cell, the first AC/DC converter having an output;
• a second SRC cell operably coupled in series with the first SRC cell, the second SRC cell comprising an input, a DC output, and a second respective power exchange circuit that includes a second respective AC/DC converter connected in parallel with the input of the second SRC cell, the second AC/DC converter having a DC output, wherein the output of the first AC/DC converter is operably coupled so as to be parallel with the DC output of the second SRC cell, and the output of the second AC/DC converter is operably coupled so as to be in parallel with the DC output of the first SRC cell;
• a controller in operable communication with the first and second SRC cells, the controller configured to:
• sense at least one variable signal from each respective SRC cell, wherein the variable signal comprises at least one signal selected from the group consisting of input voltage, input current, output voltage, and output current;
• and
• activate, based on the value of the sensed variable signal, at least one of the first and second AC/DC converters coupled to the output of a respective SRC cell, wherein the activated AC/DC converter operates so as to change the input voltage value of the respective SRC cell to which its output is connected,
• wherein the changing of the input voltage value restores an input voltage balance between the first and second SRC cells.

A multi-cell power converter, comprising:

• a plurality of groups of cells, each group operably coupled to a common input voltage source and being constructed and arranged to be capable of providing power to a respective load, wherein each group of cells comprises:
• a plurality of dual power converter cells connected in series, each power converter cell including a ZVS assistance network and being operably coupled to a respective transformer via a respective set of primary windings;
• and
• an output rectifier portion, wherein each respective power converter cell in the plurality of power converter cells is coupled to the output rectifier portion via a respective set of secondary windings on each respective transformer, wherein each respective set of secondary windings is connected in parallel;
• and
• a controller in operable communication with at least a portion of the plurality of groups of cells, the controller providing regulation for each respective load connected to each respective group with which the controller is in operable communication, wherein the controller receives at least one of a voltage signal, a current signal, and a power signal from each group with which it is in operable communication and, based at least in part on the at least one of a voltage signal, a current signal, and a power signal, provides a corresponding control signal to the respective group.

A method of providing power to multiple loads from a single voltage source, the method comprising:

• connecting a plurality of power converter cells in a cascade connected arrangement to form a plurality of groups of cells, wherein each power converter cell in each group is associated with a ZVS assistance network and is operably coupled to a respective transformer via a respective set of primary windings, and wherein each group of cells is operably coupled to a common input voltage source;
• operably coupling each respective power converter cell in the group to an output rectifier portion via a respective set of secondary windings on each respective transformer, wherein each respective set of secondary windings is connected in parallel;
• sampling at least a portion of the power-related signals in the group;
• and
• regulating each respective load operably coupled to each respective group, based at least in part on the sampled power related signals.