Grid-tied power conversion circuits and related techniques

• US 8,670,254 B2
• Filed: 01/21/2011
• Issued: 03/11/2014
• Est. Priority Date: 01/22/2010
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Perreault, David J., Pierquet, Brandon J.
• Primary Examiner(s): PATEL, RAJNIKANT B
• Application Number:
  US13/011,317
• Publication Number:
  US 20110181128A1
• Time in Patent Office: 1,145 Days
• Field of Search: 363 16- 20, 363 2101- 2103, 363/49, 363/65, 363/72, 363/79, 363/89, 363/95, 363/97, 363/98, 363/159
• US Class Current: 363/71
• CPC Class Codes: H02M 7/797 using semiconductor devices only

Abstract

Circuit topologies and control methods for a power converter and are described.

Claims

1. A power conversion circuit having an input port configured to receive a direct current (DC) input and an output port at which an alternating current (AC) output is provided, the power conversion circuit comprising:

an inverter circuit having an input port coupled to the input port of the power conversion circuit and providing an AC output current at an inverter output port;

a transformer circuit having a low-voltage port and a high-voltage port, said transformer circuit configured to provide voltage transformation between the low-voltage port and the high-voltage port;

a cycloconverter circuit having a cycloconverter input port coupled to said transformer and an output port coupled to the output port of the power conversion circuit; and

a buffer block circuit series coupled between at least two of;

said inverter;

said transformer; and

said cycloconverter circuit.

2. The power conversion circuit of claim 1 wherein said buffer block circuit is configured to absorb local average differences in power between that received at the input port of the power conversion circuit and delivered to the output port of the power conversion circuit.

3. The power conversion circuit of claim 1 wherein said buffer block circuit comprises a storage element and a switch element and in response to a changing voltage of an AC signal provided to said buffer block circuit, said switch element switches to absorb or deliver power to said storage element such that said buffer block circuit compensates for a power mismatch between the input and output ports of said power conversion circuit.

4. The power conversion circuit of claim 1 wherein said buffer block circuit is series coupled between two of:

the output port of said inverter;

the low-voltage port of said transformer;

the high-voltage port of said transformer; and

the input port of said cycloconverter circuit.

5. The power conversion circuit of claim 1 wherein said buffer block circuit is provided having two terminals with a first terminal coupled to one of:

the output port of said inverter;

the low-voltage port of said transformer;

the high-voltage port of said transformer; and

the input port of said cycloconverter circuit; and

a second terminal coupled to a second different one of;

the output port of said inverter;

the low-voltage port of said transformer;

the high-voltage port of said transformer; and

the input port of said cycloconverter circuit such that said buffer block circuit is series coupled between at least two of;

said inverter, said transformer; and

said cycloconverter circuit.

6. The power conversion circuit of claim 1 wherein said buffer block circuit comprises:

a storage element having first and second terminals, with a first one of the first and second terminals coupled to the first terminal of said buffer block circuit; and

a switching element having a first terminal coupled to a second one of the first and second terminals of said storage element and a second terminal coupled to the second terminal of said buffer block circuit.

7. The power conversion circuit of claim 6 wherein said storage element corresponds to a capacitor and said switching element comprises one or more switches.

8. The power conversion circuit of claim 7 wherein said switching element comprises a plurality of switches configured as a half bridge circuit.

9. The power conversion circuit of claim 1 wherein said inverter circuit is provided as a soft-switched resonant inverter circuit which provides a high-frequency (HF) AC signal at the output port thereof.

10. The power conversion circuit of claim 1 wherein in response to a changing voltage of an AC signal provided to the output port of said cycloconverter, said cycloconverter modulates the transfer of current between the input and output ports of said cycloconverter.

11. The power conversion circuit of claim 1 wherein said cycloconverter comprises first and second half-bridge circuits.

12. The power conversion circuit of claim 11 wherein said first and second half-bridge circuits correspond to first and second unidirectional voltage blocking half-bridge circuits coupled in a back-to-back configuration.

13. The power conversion circuit of claim 1 wherein said cycloconverter is controlled to provide a phase-shift between a resonant current and a synthesized half-bridge voltage of at least one of:

said buffer block circuit or said cycloconverter such that said cycloconverter manages power transfer between said buffer block circuit and said cycloconverter.

14. The power conversion circuit of claim 1 wherein the relative phases of the switching timing patterns of said inverter, said buffer block circuit and said cycloconverter circuit are selected such that a desired power transfer is achieved among the input port, the output port, and said buffer block.

15. The power conversion circuit of claim 1 wherein said cycloconverter comprises

a first half-bridge circuit having first, second and third terminals;

and

a second half-bridge circuit having first, second and third terminals wherein the first terminal of each of the first and second half-bridge circuits form a port corresponding to the input of the cycloconverter circuit, the second terminal of each of the first and second half-bridge circuits form a port corresponding to the output of the cycloconverter circuit and the third terminal of the first half-bridge circuit is coupled to the third terminal of the second half-bridge circuit.

16. The power conversion circuit of claim 15 wherein for a first polarity of an output voltage signal provided at the output of the cycloconverter circuit, the first and second switches of the first half-bridge circuit are biased into their conduction states and the first and second switches of the second half-bridge are modulated.

17. The power conversion circuit of claim 16 wherein for a second different polarity of an output voltage signal provided at the output of the cycloconverter circuit, the first and second switches of the second half-bridge circuit are biased into their conduction states and the first and second switches of the first half-bridge circuit are modulated.

18. A power conversion circuit having a pair of input terminals configured to receive a direct current (DC) voltage signal and a pair of output terminals at which an alternating current (AC) voltage signal is provided, the power conversion circuit comprising:

an inverter circuit having a pair of input terminals corresponding to the input terminals of the power conversion circuit and having a pair of output terminals and wherein said inverter circuit is configured to convert between a DC voltage signal at the pair of input terminals and a high-frequency AC signal at the pair of output terminals;

a transformation stage having a pair of input terminals coupled to the pair of output terminals of said inverter circuit and having a pair of output terminals wherein said transformation stage is configured provide voltage scaling of the high-frequency AC signal at the output of the inverter circuit and isolates said inverter circuit; and

a cycloconverter having a pair of input terminals coupled to the pair of output terminals of said transformation stage and having a pair of output terminals corresponding to the output terminals of the power conversion circuit, said cycloconverter circuit configured to receive a high-frequency AC signal from said transformation stage and to frequency convert between the high-frequency AC signal and the AC signal at the pair of output terminals of said cycloconverter, said cycloconverter comprising;

a first half-bridge circuit having first, second and third terminals; and

a second half-bridge circuit having first, second and third terminals wherein the first terminal of each of the first and second half-bridge circuits correspond to the input of the cycloconverter circuit, the second terminal of each of the first and second half-bridge circuits correspond to the output of the cycloconverter circuit and the third terminal of the first half-bridge circuit is coupled to the third terminal of the second half-bridge circuit;

wherein the first half-bridge circuit of said cycloconverter circuit comprises first and second switches each having first, second and third terminals and a bypass capacitor.

19. The power conversion circuit of claim 18 wherein for a first range of an output voltage signal provided at the output of the cycloconverter circuit, the first and second switches of the first half-bridge circuit are biased into their conduction states and the first and second switches of the second half-bridge are modulated.

20. The power conversion circuit of claim 19 wherein for a second separate range of an output voltage signal provided at the output of the cycloconverter circuit, the first and second switches of the second half-bridge circuit are biased into their conduction states and the first and second switches of the first half-bridge circuit are modulated.

21. The power conversion circuit of claim 18 wherein, for at least some operating conditions, the first switch of the first half-bridge circuit and the second switch of the second half-bridge circuit are modulated on and off together substantially simultaneously, and the second switch of the first half-bridge circuit and the first switch of the second half-bridge circuit are modulated on and off together substantially simultaneously.

22. A cycloconverter circuit having an input and an output, cycloconverter circuit comprising:

a first half-bridge circuit having first, second and third terminals, said first half-bridge circuit comprising first and second switches each having first, second and third terminals and a bypass capacitor; and

a second half-bridge circuit having first, second and third terminals, said second half-bridge circuit comprising first and second switches each having first, second and third terminals and a bypass capacitor wherein the first terminal of each of the first and second half-bridge circuits correspond to the input of the cycloconverter circuit, the second terminal of each of the first and second half-bridge circuits correspond to the output of the cycloconverter circuit and the third terminal of the first half-bridge circuit is coupled to the third terminal of the second half-bridge circuit.

23. The cycloconverter circuit of claim 22 wherein for a first range of an output voltage signal provided at the output of the cycloconverter circuit, the first and second switches of the first half-bridge circuit are biased into their conduction states and the first and second switches of the second half-bridge are modulated and wherein for a second different range of an output voltage signal provided at the output of the cycloconverter circuit, the first and second switches of the second half-bridge circuit are biased into their conduction states and the first and second switches of the first half-bridge circuit are modulated.

24. The cycloconverter circuit of claim 22 wherein, for at least some operating conditions, the first switch of the first half-bridge circuit and the second switch of the second half-bridge circuit are modulated on and off together and the second switch of the first half-bridge circuit and the first switch of the second half-bridge circuit are modulated on and off together.