Multi-mode power converters incorporating balancer circuits and methods of operation thereof

A converter according to claim 3, wherein the first switch is constrained to decouple the first voltage bus from the neutral bus when the second voltage bus is coupled to the neutral bus, and wherein the second switch is constrained to decouple the second voltage bus from the neutral bus when the first voltage bus is coupled to the neutral bus.

A converter according to claim 3, wherein the balancer circuit is operative to switch both of the first and second switches at 50% duty cycles to maintain the first and second voltages at substantially the same magnitude.

A converter according to claim 3, wherein the balancer circuit is responsive to an AC input voltage applied to the input node of the first switching circuit to vary the respective duty cycles at which the first and second switches operate.

A converter according to claim 3, wherein the balancer circuit comprises an inductor having a first terminal coupled to the neutral bus, and wherein the first and second switches are operative to selectively couple a second terminal of the inductor to respective ones of the first and second voltage busses.

A converter according to claim 3, wherein the balancer circuit comprises a transformer including a first winding having a first tap coupled to the first and second switches and a second tap coupled to the neutral bus, and wherein the first and second switches selectively couple the first tap of the transformer to the first and second voltage busses.

A converter according to claim 10, wherein the battery converter circuit comprises: an inductor configured to be connected in series with a battery; a first switch operative to selectively couple one end of a series combination of a battery and the inductor to one of the first or second voltage busses; and a second switch operative to selectively couple the one end of the series combination of a battery and an inductor to another end of the series combination of a battery and the inductor.

A converter according to claim 20, wherein the switch control circuit is operative to vary respective duty cycles at which the first, second, third and fourth switches are operated responsive to the AC input voltage.

A converter according to claim 20: wherein the switch control circuit is operative, when the AC input voltage is at a nominal level, to provide a substantially continuous low impedance connection between the AC power source and the load through the rectifier and inverter circuits; wherein the switch control circuit is operative, when the AC input voltage is less than the nominal level, to cause the rectifier circuit to boost the magnitudes of the first and second DC voltages while providing respective substantially continuous low impedance connections between the load and respective ones of the first and second voltages busses through the inverter circuit during respective positive and negative half-cycles of the AC input voltage; and wherein the switch control circuit is operative, when the AC input voltage is greater than the nominal level, to provide respective substantially continuous low-impedance connections between the AC power source and respective ones the first and second voltage busses through the rectifier circuit during respective positive and negative half-cycles of the AC input voltage, while causing the inverter circuit to buck the magnitude of a voltage generated at the load from the first and second DC voltages.

A converter according to claim 20: wherein the switch control circuit is operative, when the AC input voltage is at a nominal level, to: switch the first and second switches at substantially complementary duty cycles of approximately 100% and approximately 0%, respectively, while switching the third and fourth switches at substantially complementary duty cycles of approximately 100% and approximately 0%, respectively, during a first positive half-cycle of the AC input voltage; and switch the first and second switches at substantially complementary duty cycles of approximately 0% and approximately 100%, respectively, while switching the third and fourth switches at substantially complementary duty cycles of approximately 0% and approximately 100%, respectively, during a first negative half-cycle of the AC input voltage; wherein the switch control circuit is operative, when the AC input voltage is at less than the nominal level, to: switch the first and second switches at substantially complementary duty cycles sufficiently less than 100% and sufficiently greater than 0%, respectively, to boost the magnitude of the first DC voltage, while switching the third and fourth switches at substantially complementary cycles of approximately 100% and approximately 0%, respectively, during a second positive cycle of the AC input voltage; and switch the first and second switches at substantially complementary duty cycles sufficiently greater than 0% and sufficiently less than 0%, respectively, to boost the magnitude of the second DC voltage, while switching the third and fourth switches at substantially complementary cycles of approximately 0% and approximately 100%, respectively, during a second negative half-cycle of the AC input voltage; and wherein the switch control circuit is operative, when the AC input voltage is greater than the nominal level, to: switch the first and second switches at substantially complementary duty cycles of approximately 100% and approximately 0%, respectively, while switching the third and fourth switches at substantially complementary cycles sufficiently less than 100% and sufficiently greater than 0%, respectively, to buck a voltage applied to the load, during a third positive cycle of the AC input voltage; and switch the first and second switches at substantially complementary duty cycles of approximately 0% and approximately 100%, respectively, while switching the third and fourth switches at substantially complementary cycles sufficiently greater than 0% and sufficiently less than 100%, respectively, to buck a voltage applied to the load, during a third negative cycle of the AC input voltage.

A converter according to claim 26, wherein the switch control circuit is responsive to an AC input voltage applied to the rectifier circuit to control operation of the first, second, third, fourth, fifth and sixth switches.

A converter according to claim 26, wherein the third inductor comprises a first winding of a transformer, the transformer having a second winding inductively coupled to the first winding, and further comprising an AC voltage generating circuit coupled to the second winding of the transformer, configured to connect to a battery, and operative to generate an AC voltage on the second winding of the transformer from a DC voltage produced by the battery.

A method according to claim 35, further comprising the step of varying respective duty cycles at which the first, second, third and fourth switches are operated responsive to the AC input voltage.

A method according to claim 35, comprising the steps of: providing a substantially continuous low impedance connection between the phase bus and the load through selected combinations of the first, second, third and fourth switches when the AC input voltage is approximately at a nominal level; switching the first and second switches to boost the magnitudes of the first and second DC voltages while providing respective substantially continuous low impedance connections between the load and respective ones of the first and second voltages busses through respective ones of the third and fourth switches during respective positive and negative half-cycles of the AC input voltage, when the AC input voltage is less than the nominal level; and providing respective substantially continuous low-impedance connections between the AC power source and respective ones the first and second voltage busses through respective ones of the first and second switches during respective positive and negative half-cycles of the AC input voltage, while bucking a voltage generated at the load from the first and second DC voltages, when the AC input voltage is greater than the nominal level.

A method according to claim 35, comprising the steps of: when the AC input voltage is at a nominal level: switching the first and second switches at substantially complementary duty cycles of approximately 100% and approximately 0%, respectively, while switching the third and fourth switches at substantially complementary duty cycles of approximately 100% and approximately 0%, respectively, during a first positive half-cycle of the AC input voltage; and switching the first and second switches at substantially complementary duty cycles of approximately 0% and approximately 100%, respectively, while switching the third and fourth switches at substantially complementary duty cycles of approximately 0% and approximately 100%, respectively, during a first negative half-cycle of the AC input voltage; when the AC input voltage is less than the nominal level: switching the first and second switches at substantially complementary duty cycles sufficiently less than 100% and sufficiently greater than 0%, respectively, to boost the magnitude of the first DC voltage, while switching the third and fourth switches at substantially complementary cycles of approximately 100% and approximately 0%, respectively, during a second positive cycle of the AC input voltage; and switching the first and second switches at substantially complementary duty cycles sufficiently greater than 0% and sufficiently less than 100%, respectively, to boost the magnitude of the second DC voltage, while switching the third and fourth switches at substantially complementary cycles of approximately 0% and approximately 100%, respectively, during a second negative half-cycle of the AC input voltage; and when the AC input voltage is greater than the nominal level, to: switching the first and second switches at substantially complementary duty cycles of approximately 100% and approximately 0%, respectively, while switching the third and fourth switches at substantially complementary cycles sufficiently less than 100% and sufficiently greater than 0%, respectively, to buck a voltage applied to the load, during a third positive cycle of the AC input voltage; and switching the first and second switches at substantially complementary duty cycles of approximately 0% and approximately 100%, respectively, while switching the third and fourth switches at substantially complementary cycles sufficiently greater than 0% and sufficiently less than 100%, respectively, to buck a voltage applied to the load, during a third negative cycle of the AC input voltage.