DC-DC converter

• US 9,595,876 B2
• Filed: 02/11/2015
• Issued: 03/14/2017
• Est. Priority Date: 02/11/2015
• Status: Active Grant

• Current Assignee: Schneider Electric IT Corporation (Schneider Electric SE)
• Original Assignee: Schneider Electric IT Corporation (Schneider Electric SE)
• Inventors: Nielsen, Henning Roar
• Primary Examiner(s): Dole, Timothy J
• Assistant Examiner(s): Tiku, Sisay G
• Application Number:
  US14/619,721
• Publication Number:
  US 20160233776A1
• Time in Patent Office: 762 Days
• Field of Search: 363 15- 17, 363 2101- 2102, 363 2104- 2109, 363/21.1, 363/21.11
• US Class Current: 1/1
• CPC Class Codes: H02M 1/0074 Plural converter units whose inputs are connected in series
• CPC Class Codes: H02M 1/346 Passive non-dissipative snubbers
• CPC Class Codes: H02M 3/33546 with automatic control of the output voltage or current H02M3/33561 takes precedence
• CPC Class Codes: H02M 3/33584 Bidirectional converters
• CPC Class Codes: H02M 3/33592 having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
• CPC Class Codes: H02M 3/3378 in a push-pull configuration of the parallel type H02M3/3374 takes precedence
• CPC Class Codes: H02M 7/49 Combination of the output voltage waveforms of a plurality of converters
• CPC Class Codes: H02M 7/5387 in a bridge configuration
• 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

Power converters and methods of converting power are provided. In one aspect a converter includes an input to receive an input voltage having an input voltage value, an output, a first voltage bus, a midpoint, a first transformer having a primary and a secondary, a first circuit coupled to the input, coupled between the midpoint and the first voltage bus and coupled to the primary of the first transformer, an output circuit coupled to the secondary of the first transformer and coupled to the output, and a control circuit coupled to the first circuit and configured to control the first circuit to provide an AC voltage at the primary of the first transformer, wherein the control circuit is configured to control switches of the first circuit using a modified triangular waveform.

Claims

1. A converter comprising:

an input to receive an input voltage having an input voltage value;

an output;

a first voltage bus;

a midpoint;

a first transformer having a primary and a secondary;

a first circuit coupled to the input, coupled between the midpoint and the first voltage bus and coupled to the primary of the first transformer;

an output circuit coupled to the secondary of the first transformer and coupled to the output; and

a control circuit coupled to the first circuit and configured to control the first circuit to provide an AC voltage at the primary of the first transformer, wherein the control circuit is configured to generate control signals to control switches of the first circuit using a modified triangular waveform, wherein the modified triangular waveform does not follow a triangular shape over a complete cycle of the waveform, wherein the modified triangular waveform has slope values including at least a positive slope and a negative slope.

2. The converter of claim 1, further comprising:

a second voltage bus;

a second transformer having a primary and a secondary;

a second circuit coupled to the input, coupled between the midpoint and the second voltage bus and coupled to the primary of the second transformer;

wherein the secondary of the second transformer is coupled to the output circuit, and wherein the control circuit is coupled to the second circuit and configured to control switches of the second circuit using a modified triangular waveform.

3. The converter of claim 2, wherein the control circuit is configured to control the converter in a recharge mode of operation to generate a DC voltage at the input from a DC voltage at the output.

4. The converter of claim 2, wherein each of the first circuit and the second circuit includes a plurality of switch legs coupled between one of the first voltage bus and the second voltage bus and the midpoint.

5. The converter of claim 4, wherein each of the first transformer and the second transformer has a one to one turn ratio.

6. The converter of claim 5, wherein an output DC voltage at the output is equal to twice the voltage from the first voltage bus to the midpoint.

7. The converter of claim 4, wherein each of the plurality of legs includes an outer switch and an inner switch, with a capacitor coupled across each inner switch, and wherein the converter further includes at least one passive discharge circuit coupled to at least one capacitor coupled across an inner switch, wherein the discharge circuit is configured to discharge the capacitor and reduce a turn-off loss associated with the inner switch.

8. The converter of claim 2, wherein the output includes a positive output, a negative output and a midpoint.

9. A voltage conversion method comprising:

receiving at an input an input DC voltage, the input DC voltage having a voltage value;

creating a second voltage from the input voltage at a first voltage bus;

generating a plurality of control signals using a modified triangular waveform, wherein the modified triangular waveform has at least three slope values during a positive portion of a waveform cycle, wherein the modified triangular waveform has slope values including at least a positive slope and a negative slope;

creating a first AC voltage from the second voltage using a first plurality of switches by controlling each of the first plurality of switches using one of the plurality of control signals;

providing the first AC voltage at a primary of a first transformer; and

generating an output voltage at an output from an AC voltage at a secondary of the first transformer.

10. The method of claim 9, further comprising:

creating a third voltage from the input voltage at a second voltage bus;

creating a second AC voltage from the third voltage using a second plurality of switches by controlling each of the second plurality of switches using one of the plurality of control signals;

providing the second AC voltage at a primary of a second transformer; and

generating an output voltage from an AC voltage at a secondary of the second transformer.

11. The method of claim 10 further comprising configuring the first plurality of switches as a plurality of switch legs coupled between the first voltage bus and a midpoint, and configuring the second plurality of switches as a plurality of switch legs coupled between the second voltage bus and the midpoint.

12. The method of claim 11, wherein each of the first transformer and the second transformer has a one to one turn ratio.

13. The method of claim 11, further comprising providing a DC voltage at the output having a DC voltage value equal to twice the voltage from the first voltage bus to the midpoint.

14. The method of claim 11, wherein each of the plurality of legs includes an outer switch and an inner switch, with a capacitor coupled across each inner switch, and wherein the method further includes discharging each capacitor of each inner switch to reduce a turn-off loss associated with each inner switch.

15. The method of claim 9, further comprising coupling a battery to the input and providing a voltage at the battery to charge the battery using the first plurality of switches from an input voltage at the output.

16. The method of claim 9, wherein the output includes a positive output, a negative output and a midpoint, and the method further includes providing a first output voltage from the positive output and the midpoint, and providing a second output voltage from the midpoint to the negative output.

17. A converter comprising;

an input to receive an input voltage having an input voltage value;

an output to provide an output voltage;

a first voltage bus having a DC bus voltage value;

a midpoint;

a first transformer having a primary and a secondary;

a first circuit coupled to the input, coupled between the midpoint and the first voltage bus and coupled to the primary of the first transformer;

an output circuit coupled to the secondary of the first transformer and coupled to the output; and

means for controlling the first circuit to generate a three level voltage waveform at the primary of the first transformer over a range of input voltage values using a modified triangular waveform, wherein the modified triangular waveform does not follow a triangular shape over a complete cycle of the waveform, wherein the modified triangular waveform has slope values including at least a positive slope and a negative slope.

18. The converter of claim 17, wherein the range of input voltage values extends from a value equal to 0.3 times the DC bus voltage value and 0.7 times the DC bus voltage value.

19. The converter of claim 17, further comprising means for operating the converter in a recharge mode of operation to generate a DC voltage at the input from a DC voltage at the output.

20. The converter of claim 17, wherein the first circuit includes a plurality of switch legs coupled between the first voltage bus and the midpoint, wherein each of the plurality of legs includes an outer switch and an inner switch, with a capacitor coupled across each inner switch, and wherein the converter further includes means for discharging the capacitor and for reducing a turn-off loss associated with the inner switch.