Bidirectional power converter having a charger and export modes of operation

• US 9,584,047 B2
• Filed: 03/14/2014
• Issued: 02/28/2017
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: HDT Expeditionary Systems, Inc. (HDT Global, Inc.)
• Original Assignee: HDT Expeditionary Systems, Inc. (HDT Global, Inc.)
• Inventors: Frohman, Gene H., Ramsay, Scott, Roche, Keven, Parsons, Thomas, Kelley, Michael, Thompson, John, McMillan, Scott, Farace, Jessica, Tarca, Matthew, Gellis, David
• Primary Examiner(s): Berhane, Adolf
• Assistant Examiner(s): Quddus, Nusrat
• Application Number:
  US14/211,719
• Publication Number:
  US 20140268959A1
• Time in Patent Office: 1,082 Days
• Field of Search: 363/13, 363/16, 363/17, 363/97, 363/98, 363/123, 363/125, 363/127, 363131-134
• US Class Current: 1/1
• CPC Class Codes: H02M 5/297 for conversion of frequency
• CPC Class Codes: H02M 7/4807 having a high frequency intermediate AC stage
• CPC Class Codes: H02M 7/797 using semiconductor devices only

Abstract

A bidirectional power converter that can be used in an electric vehicle to perform AC to DC power conversion to charge the electric vehicle'"'"'s battery and to perform DC to AC power conversion to export power to run external electrical loads is described. The bidirectional power converter may include an AC interface coupled to a cyclo-inverter circuit, and a DC interface coupled to a H-bridge circuit. The cyclo-inverter can be electrically coupled to the H-bridge circuit through a transformer. The bidirectional power converter may include a neutral terminal on the AC interface that is coupled to the transformer through a filtering inductor.

Claims

1. A bidirectional power converter comprising:

a H-bridge circuit including;

a DC interface including a positive DC terminal and a negative DC terminal;

a first H-bridge leg coupled across the DC interface, the first H-bridge leg including a first switching circuit controlled by a first switching signal, and a second switching circuit coupled to the first switching circuit in series and controlled by a second switching signal; and

a second H-bridge leg coupled across the DC interface, the second H-bridge leg including a third switching circuit controlled by a third switching signal, and a fourth switching circuit coupled to the third switching circuit in series and controlled by a fourth switching signal; and

a cyclo-inverter circuit electrically coupled to the H-bridge circuit, the cyclo-inverter circuit including;

an AC interface including a first AC line terminal and a second AC line terminal;

a first cyclo-inverter leg including a fifth switching circuit controlled by a fifth switching signal, and a sixth switching circuit coupled to the fifth switching circuit in series and controlled by a sixth gating signal, wherein the first AC line terminal is coupled between the fifth switching circuit and the sixth switching circuit, and wherein in a charger mode of operation, the duty cycles of the fifth switching signal and the sixth switching signal are varied; and

a second cyclo-inverter leg including a seventh switching circuit controlled by the sixth gating signal, and an eight switching circuit coupled to the seventh switching circuit in series and controlled by the fifth switching signal, wherein the second AC line terminal is coupled between the fifth switching circuit and the sixth switching circuit.

2. The bidirectional power converter of claim 1, wherein in an export mode of operation, the first switching signal is 180 degrees out of phase with the second switching signal, the third switching signal is 180 degrees out of phase with the fourth switching signal, and the fifth switching signal is 180 degrees out of phase with the sixth switching signal.

3. The bidirectional power converter of claim 2, wherein in the export mode of operation, the phase of the first switching signal with respect to the third switching signal is varied.

4. The bidirectional power converter of claim 2, wherein in the export mode of operation, the fifth switching signal is switched synchronously with the first switching signal during a negative amplitude phase of an AC output, and the sixth switching signal is switched synchronously with the first switching signal during a positive amplitude phase of the AC output.

5. The bidirectional power converter of claim 1, wherein in the charger mode of operation, the first switching signal, the second switching signal, the third switching signal, and the fourth switching signal are idle.

6. The bidirectional power converter of claim 1, further comprising a DC-DC converter coupled to the DC interface.

7. The bidirectional power converter of claim 6, wherein the DC-DC converter is a neutral point clamped circuit controlled by a plurality of staggered switching signals.

8. The bidirectional power converter of claim 6, wherein the DC-DC converter is a buck-boost circuit.

9. The bidirectional power converter of claim 1, further comprising an AC tracker for filtering an input AC signal at the AC interface, the filtered input AC signal being used for controlling the switching circuits of the bidirectional power converter in a charger mode of operation.

10. The bidirectional power converter of claim 9, wherein the AC tracker includes:

a recursive filter;

a zero-crossing counter for determining a line frequency at the AC interface; and

a coefficient update unit for updating a plurality of coefficients used in the recursive filter.

11. The bidirectional power converter of claim 10, wherein the coefficient update unit updates the plurality of coefficients when the line frequency shifts from a first frequency band to a second frequency band.

12. The bidirectional power converter of claim 10, wherein the coefficient update unit updates the plurality of coefficients when changes in the line frequency satisfy a hysteresis.

13. The bidirectional power converter of claim 1, wherein power is transferred at an interface between the H-bridge circuit and the cyclo-inverter circuit without any AC line frequency component.

14. The bidirectional power converter of claim 1, wherein in a charger mode of operation, the switching circuits of the bidirectional power converter are controlled based on a target DC bus regulation voltage instead of being based on a feedback from an actual measured DC bus voltage.

15. The bidirectional power converter of claim 1, wherein in a charger mode of operation, the instantaneous output power on the DC interface is maintained to be approximately equal to the instantaneous input power on the AC interface.

16. A method for converting power, the method comprising:

receiving an input power signal;

generating a power carrier signal based on the input power signal and having alternating pulses of positive voltage and negative voltage;

modulating pulse widths of the alternating pulses in the power carrier signal;

applying the modulated power carrier signal to a first winding of a transformer;

receiving the modulated power carrier signal at a second winding of the transformer; and

rectifying the modulated power carrier signal received at the second winding of the transformer to generate an output power signal,

wherein when the input power signal is an input AC power signal, the output power signal is a output DC power signal, the method further comprises;

receiving the input AC power signal at a recursive filter;

determining a frequency of the input AC power signal;

correlating the determined frequency to a frequency band; and

updating coefficients of the recursive filter based on the frequency band, and

wherein when the input power signal is an input DC power signal, the output power signal is an output AC power signal and the modulated power carrier signal does not include a line frequency component of the output AC power signal.

17. The method of claim 16, wherein correlating the determined frequency to a frequency band is based on a hysteresis.

18. A bidirectional power converter comprising:

a H-bridge circuit including;

a DC interface including a positive DC terminal and a negative DC terminal;

a first H-bridge leg coupled across the DC interface, the first H-bridge leg including a first switching circuit controlled by a first switching signal, and a second switching circuit coupled to the first switching circuit in series and controlled by a second switching signal; and

a second H-bridge leg coupled across the DC interface, the second H-bridge leg including a third switching circuit controlled by a third switching signal, and a fourth switching circuit coupled to the third switching circuit in series and controlled by a fourth switching signal;

a cyclo-inverter circuit electrically coupled to the H-bridge circuit, the cyclo-inverter circuit including;

an AC interface including a first AC line terminal and a second AC line terminal;

a first cyclo-inverter leg including a fifth switching circuit controlled by a fifth switching signal, and a sixth switching circuit coupled to the fifth switching circuit in series and controlled by a sixth gating signal, wherein the first AC line terminal is coupled between the fifth switching circuit and the sixth switching circuit; and

a second cyclo-inverter leg including a seventh switching circuit controlled by the sixth gating signal, and an eight switching circuit coupled to the seventh switching circuit in series and controlled by the fifth switching signal, wherein the second AC line terminal is coupled between the fifth switching circuit and the sixth switching circuit; and

an AC tracker for filtering an input AC signal at the AC interface, the filtered input AC signal being used for controlling the switching circuits of the bidirectional power converter in a charger mode of operation.

19. The bidirectional power converter of claim 18, wherein the AC tracker includes one or more of:

a recursive filter;

a zero-crossing counter for determining a line frequency at the AC interface; and

a coefficient update unit for updating a plurality of coefficients used in the recursive filter.