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

• US 7,986,535 B2
• Filed: 07/10/2008
• Issued: 07/26/2011
• Est. Priority Date: 07/17/2007
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Holmansky, Evgeny N., Jacobson, Boris S.
• Primary Examiner(s): Sterrett; Jeffrey L
• Application Number:
  US12/170,498
• Publication Number:
  US 20090021966A1
• Time in Patent Office: 1,111 Days
• Field of Search: 363/17, 363/65, 363/98
• US Class Current: 363/17
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 1/0074 Plural converter units whose inputs are connected in series
• CPC Class Codes: H02M 1/008 Plural converter units for generating at two or more independent and non-parallel outputs, e.g. systems with plural point of load switching regulators
• CPC Class Codes: H02M 1/34 Snubber circuits
• CPC Class Codes: H02M 1/342 Active non-dissipative snubbers
• CPC Class Codes: H02M 3/285 Single converters with a plurality of output stages connected in parallel parallel operation of a plurality of converters in dc distribution networks H02J1/10
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A method of providing power to a load is provided. A first series resonant converter is provided. A second SRC is operably coupled to the first SRC in a cascade connected arrangement. First and second zero voltage switching (ZVS)-assistance networks are operably coupled between the first SRC and the second SRC, such that the first and second ZVS-assistance networks are providing first and second ZVS-assistant currents flowing from each ZVS-assistance network to the cascade connected arrangement of SRCs. Power from a power source is received at the cascade connected arrangement of first and second SRCs, power from a power source. The cascade connected arrangement of first and second SRCs supplies an output voltage to the load in response to receiving power from the power source.

Claims

1. A method of providing power to a load, the method comprising the unordered steps of:

providing a first series resonant converter (SRC);

operably coupling a second SRC to the first SRC in a cascade connected arrangement;

operably coupling first and second zero voltage switching (ZVS)-assistance networks between the first SRC and the second SRC, the first and second ZVS-assistance networks providing first and second ZVS-assistant currents flowing from each ZVS-assistance network to the cascade connected arrangement of SRCs;

receiving, at the cascade connected arrangement of first and second SRCs, power from a power source; and

supplying, from the cascade connected arrangement of first and second SRCs, an output voltage to the load in response to receiving power from the power source.

2. The method of claim 1, further comprising the unordered step of adjusting the value of at least one of the first and second ZVS assistance currents if the value of the ZVS assistance current deviates from a predetermined reference current value.

3. The method of claim 2, wherein each respective SRC comprises at least one respective switching element and the predetermined reference current value corresponds to the lowest level of current in the respective ZVS-assistance network sufficient for ZVS operation of all switching elements in the respective SRC.

4. The method of claim 2, wherein each of the first and second ZVS assistance networks further comprises a controllable inductor, and wherein the method further comprises changing the value of the inductance of at least one of the controllable inductors when the at least one of the ZVS-assistance currents deviates from a values that ensure proper ZVS operation.

5. The method of claim 1, wherein each ZVS-assistance network further comprises a respective controllable inductor, and wherein the method further comprises changing the inductance value of the respective controllable inductor if the current flowing through the respective ZVS-assistance network deviates from a predetermined value.

6. A dual power converter, comprising:

a first series resonant converter (SRC) operably coupled to a second SRC in a cascade connected arrangement; and

first and second zero voltage switching (ZVS)-assistance networks operably coupled between the first and second SRCs.

7. The dual power converter of claim 6, further comprising a first sensor comparing a current flowing through the first ZVS-assistance network to the first and second SRCs.

8. The dual power converter of claim 7, further comprising a second sensor comparing a current flowing through the second ZVS-assistance network to the first and second SRCs.

9. The dual power converter of claim 8, further comprising a controller in operable communication with the first and second sensors and the first and second ZVS assistance networks, the controller being operable to change the value of the current flowing through at least one of the first and second ZVS assistance networks to at least one of the first and second SRCs if the current deviates from a predetermined value.

10. The dual power converter of claim 9, wherein each of the first and second ZVS-assistance networks comprises a controllable inductor, and wherein the controller is operable to change the value of at least one of the first and second controllable inductors if the current flowing throughout least one of the first and second ZVS-assistance networks deviates from at least one of a predetermined value.

11. 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.

12. 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 output 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 output 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.

13. 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.

14. The multi-cell power converter of claim 13, wherein at least a portion of the power converter cells comprise dual SRC cells, each dual SRC cell comprising:

a first series resonant converter (SRC) operably coupled to a second SRC in a cascade connected arrangement;

first and second zero voltage switching (ZVS)-assistance networks operably coupled in parallel between the first and second SRCs;

a first sensor comparing a current flowing through the first ZVS-assistance network to the first and second SRCs;

a second sensor comparing a current flowing through the second ZVS-assistance network to the first and second SRCs; and

a cell controller in operable communication with the first and second sensors and the first and second ZVS assistance networks, the controller being operable to change the value of the current flowing throughout least one of the first and second ZVS assistance networks to at least one of the first and second SRCs if the current deviates from a predetermined value.

15. The multi-cell power converter of claim 14, wherein each of the first and second ZVS-assistance networks comprises a respective controllable inductor, and wherein the cell controller is operable to change the value of at least one of the respective first and second controllable inductors if the current flowing from at least one of the first and second ZVS-assistance networks deviates from a value that ensures proper ZVS operation.

16. The multi-cell power converter of claim 13, wherein at least a portion of the dual power converter cells includes a dual SRC cell 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 output of the first SRC cell, the first AC/DC converter having an output;

a second series resonant converter (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 output 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;

an SRC cell controller in operable communication with the first and second SRC cells, the SRC cell 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.

17. 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.

18. The method of claim 17, further comprising operably coupling first and second zero voltage switching (ZVS)-assistance networks between the first power converter and the second power converter, each ZVS-assistance network providing a respective ZVS-assistant current flowing through each respective ZVS-assistance network to the first and second power converters.

19. The method of claim 18, further comprising adjusting the value of at least one of the first and second respective ZVS assistance currents if the value of the respective ZVS assistance current deviates from a predetermined reference current value.

20. The method of claim 18, wherein each of the first and second ZVS assistance networks further comprises a respective controllable inductor, and wherein the method further comprises changing the value of at least one of the respective controllable inductors when the at least one of the respective ZVS-assistance currents deviates from a predetermined minimum value.