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1. WO2018132342 - SWITCHING STRATEGY FOR INCREASED EFFICIENCY OF POWER CONVERTERS

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[ EN ]

WHAT IS CLAIMED IS:

1. A control method for operating a DC to AC converter, the DC to AC converter comprising an inner converter and an outer converter, the inner converter comprising an isolation transformer and a first plurality of switching devices, the outer converter comprising a second plurality of switching devices, the method comprising:

determining an output voltage of the outer converter; and

controlling the inner converter to be in an on state or an off state based at least in part on the output voltage of the outer converter.

2. The control method of claim 1, wherein at least one switching device in the first plurality or second plurality of switching devices comprises a silicon carbide MOSFET.

3. The control method of claim 1, wherein when the output voltage of the outer converter is zero volts, controlling operation of the inner converter based at least in part on the output voltage of the outer converter comprises controlling the inner converter to be in an off state.

4. The control method of claim 1, wherein when the output voltage of the outer converter is non-zero, controlling operation of the inner converter based at least in part on the output voltage of the outer converter comprises controlling the inner converter to be in an on state.

5. The control method of claim 1, wherein determining an output voltage of the outer converter comprises identifying one or more gate commands to the outer converter; and

wherein controlling operation of the inner converter based at least in part on the output voltage of the outer converter comprises controlling the inner converter based at least in part on the one or more gate commands to the outer converter.

6. The control method of claim 5, wherein when the one or more gate commands to the outer converter comprise a non-zero duty cycle, controlling the inner converter based at least in part on the one or more gate commands to the outer converter comprises controlling the inner converter to an on state.

7. The control method of claim 5, wherein controlling the inner converter based at least in part on the one or more gate commands to the outer converter comprises controlling a duty cycle of gate commands to the inner converter based at least in part on the duty cycle of gate commands to the outer converter.

8. The control method of claim 7, wherein the duty cycle of gate commands to the inner converter is the same as the duty cycle of gate commands to the outer converter.

9. The control method of claim 1, wherein the inner converter further comprises a first conversion entity and a second conversion entity;

wherein the first conversion entity is a DC to AC conversion entity;

wherein the second conversion entity is an AC to DC conversion entity; and wherein the isolation transformer is coupled between the first conversion entity and the second conversion entity.

10. The control method of claim 9, wherein the outer converter comprises third conversion entity; and

wherein the third conversion entity is DC to AC conversion entity.

11. The control method of claim 1, wherein the DC to AC converter comprises a plurality of DC to DC to AC inverter blocks.

12. The control method of claim 1, wherein the DC to AC converter comprises a multiphase DC to AC converter; and

wherein the control method is performed for each phase of multiphase power converted by the multiphase DC to AC converter.

13. A power conversion system, comprising:

a DC to AC converter comprising an inner converter and an outer converter, the inner converter comprising an isolation transformer and a first plurality of switching devices, the outer converter comprising a second plurality of switching devices; and

a control system configured to control operation of the DC to AC converter; wherein the control system is configured to:

determine an output voltage of the outer converter; and control the inner converter to be in an on state or an off state based at least in part on the output voltage of the outer converter.

14. The power conversion system of claim 14, wherein when the output voltage of the outer converter is zero volts, the control system is configured to control the inner converter to an off state.

15. The power conversion system of claim 14, wherein when the output voltage of the outer converter is non-zero, the control system is configured to control the inner converter to an on state.

16. The power conversion system of claim 14, wherein the control system is configured to determine an output voltage of the outer converter by identifying one or more gate commands to the outer converter; and

wherein the control system is configured to control the inner converter based at least in part on the one or more gate commands to the outer converter.

17. The power conversion system of claim 16, wherein when the one or more gate commands to the outer converter comprise a non-zero duty cycle, the control system is configured to control the inner converter to an on state.

18. The power conversion system of claim 16, wherein the control system is configured to control the inner converter based at least in part on the duty cycle of gate commands to the outer converter.

19. The power conversion system of claim 18, wherein the control system is configured to control the duty cycle of gate commands to the inner converter to match the duty cycle of gate commands to the outer converter.

20. A wind power generation system, comprising:

a wind power generator configured to generate AC power;

an AC to DC converter coupled to the wind power generator, the AC to DC converter configured to convert the AC power from the wind power generator to a DC power;

a DC link coupled to the AC to DC converter, the DC link configured to receive DC power from the AC to DC converter;

a DC to AC converter coupled to the DC link, the DC to AC converter configured to receive DC power from the DC link; the DC to AC converter comprising an inner converter and an outer converter, the inner converter comprising an isolation transformer and a first plurality of switching devices, the outer converter comprising a second plurality of switching devices, at least one switching device in the first plurality or second plurality of switching devices comprising a silicon carbide MOSFET; and

a control system configured to control operation of the DC to AC converter; wherein the control system is configured to:

determine an output voltage of the outer converter; and control the inner converter to be in an on state or an off state based at least in part on the output voltage of the outer converter;

wherein when the output voltage of the outer converter is zero volts, the control system is configured to control the inner converter to an off state; and

wherein when the output voltage of the outer converter is non-zero, the control system is configured to control the inner converter to an on state.