Multi-level Inverter With Flying Capacitor Topology

• US 20170214309A1
• Filed: 04/07/2017
• Published: 07/27/2017
• Est. Priority Date: 03/26/2014
• Status: Active Grant

• Current Assignee: Solaredge Technologies Incorporated
• Original Assignee: Solaredge Technologies Incorporated
• Inventors: Yoscovich, Ilan, Galin, Yoav, Glovinsky, Tzachi, Sella, Guy
• Granted Patent: US 10,153,685 B2
• Time in Patent Office: Days
• CPC Class Codes: H02M 1/0054 Transistor switching losses periodically suspending operation of switching converter in low power mode H02M1/0035
• CPC Class Codes: H02M 1/0095 Hybrid converter topologies, e.g. NPC mixed with flying capacitor, thyristor converter mixed with MMC or charge pump mixed with buck
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H02M 1/126 using passive filters
• CPC Class Codes: H02M 1/143 using compensating arrangements for reducing noise from the supply in transmission systems H04B15/005
• CPC Class Codes: H02M 7/483 Converters with outputs that each can have more than two voltages levels
• CPC Class Codes: H02M 7/4833 Capacitor voltage balancing
• CPC Class Codes: H02M 7/4835 comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
• CPC Class Codes: H02M 7/4837 Flying capacitor converters
• CPC Class Codes: H02M 7/537 using semiconductor devices only, e.g. single switched pulse inverters

Abstract

A multi-level inverter having one or more banks, each bank containing a plurality of low voltage MOSFET transistors. A processor configured to switch the plurality of low voltage MOSFET transistors in each bank to switch at multiple times during each cycle.

Claims

1-30. -30. (canceled)

31. An apparatus comprising a first ripple storage capacitor, a second ripple storage capacitor, a first switch, a second switch, an inductor, a central node, an input terminal, and a reference terminal, wherein:

the first ripple storage capacitor is connected between the central node and the reference terminal through the first switch;

the second ripple storage capacitor is connected between the central node and the reference terminal through the second switch; and

the inductor is connected between the central node and the input terminal.

32. The apparatus of claim 31, further comprising a control circuit including control signals output to the first switch and the second switch, wherein the control circuit is configured to operate the first switch and the second switch to:

convert an input ripple voltage at the input terminal to a first ripple voltage across the first ripple storage capacitor and a second ripple voltage across the second ripple storage capacitor.

33. The apparatus of claim 32, wherein the first ripple voltage is higher than an average direct-current voltage at the input terminal and the second ripple voltage is lower than the average direct-current voltage at the input terminal.

34. The apparatus of claim 33, wherein a gain boost of the apparatus is up to twice the average direct-current voltage.

35. The apparatus of claim 32, wherein the control circuit is configured to:

fluctuate the first ripple voltage above an average direct-current voltage at the input terminal; and

fluctuate the second ripple voltage below the average direct-current voltage.

36. The apparatus of claim 35, wherein the control circuit is configured to:

fluctuate the first ripple voltage between an average direct-current voltage at the input terminal and twice the average direct-current voltage; and

fluctuate the second ripple voltage between the average direct-current voltage and zero voltage.

37. The apparatus of claim 31, wherein the first ripple storage capacitor and the second ripple storage capacitor are directly connected to the reference terminal.

38. The apparatus of claim 31, further comprising a third switch, a fourth switch and a flying capacitor, wherein:

the first ripple storage capacitor and the first switch are connected to the central node through the third switch;

the second ripple storage capacitor and the second switch are connected to the central node through the fourth switch; and

the flying capacitor is connected between terminals of the third switch and the fourth switch that are distal from the central node.

39. The apparatus of claim 38, further comprising a control circuit including control signals output to the first switch, the second switch, the third switch, and the fourth switch, wherein the control circuit is configured to operate the first switch, the second switch, the third switch, and the fourth switch, to:

convert an input ripple voltage at the input terminal to a first ripple voltage across the first ripple storage capacitor and a second ripple voltage across the second ripple storage capacitor; and

balance a voltage across the flying capacitor to half an average direct-current voltage between the input terminal and the reference terminal

40. The apparatus of claim 31, further comprising an inverter, wherein the input terminal and reference terminal are connected across inputs of the inverter.

41. The apparatus of claim 31, wherein the first switch and the second switch are MOSFETs.

42. The apparatus of claim 31, wherein the first ripple storage capacitor and the second ripple storage capacitor are film capacitors.

43. A method comprising converting an input ripple voltage between an input terminal and a reference terminal to a first ripple voltage across a first ripple storage capacitor and a second ripple voltage across a second ripple storage capacitor by:

switching the first ripple storage capacitor between a central node and a reference terminal through a first switch; and

switching the second ripple storage capacitor between the central node and the reference terminal through a second switch, wherein the central node is connected to the input terminal through an inductor.

44. The method of claim 43, wherein the first ripple voltage is higher than an average direct-current voltage at the input terminal and the second ripple voltage is lower than the average direct-current voltage at the input terminal.

45. The method of claim 43, further comprising:

fluctuating the first ripple voltage above an average direct-current voltage at the input terminal; and

fluctuating the second ripple voltage below the average direct-current voltage at the input terminal.

46. The method of claim 45, further comprising:

fluctuating the first ripple voltage between an average direct-current voltage at the input terminal and twice the average direct-current voltage at the input terminal; and

fluctuating the second ripple voltage between the average direct-current voltage at the input terminal and zero voltage.

47. The method of claim 45, wherein the first ripple storage capacitor and the second ripple storage capacitor are directly connected to the reference terminal.

48. The method of claim 43, further comprising:

connecting the first ripple storage capacitor and the first switch to the central node through a third switch;

connecting the second ripple storage capacitor and the second switch to the central node through a fourth switch; and

connecting a flying capacitor between terminals of the third switch and the fourth switch that are distal from the central node.

49. An apparatus comprising:

an inverter;

a first capacitor connected across input terminals of the inverter, a buck-boost circuit comprising;

a pair of ripple storage capacitors; and

input terminals connected in parallel with the input terminals of the inverter and with the first capacitor.

50. The apparatus of claim 49, wherein the buck-boost circuit is configured to transfer a ripple voltage across the first capacitor to the pair of ripple storage capacitors.

51. The apparatus of claim 50, wherein the buck-boost circuit is configured to swing the ripple voltage between a first voltage across a first of the pair of ripple storage capacitors and a second voltage across a second of the pair of ripple storage capacitors.

52. The apparatus of claim 50, wherein the buck-boost circuit is configured to:

control a first voltage across a first of the pair of ripple storage capacitors to be greater than an average voltage at the input terminals of the buck-boost circuit; and

control a second voltage across a second of the pair of ripple storage capacitors to be less than the average voltage at the input terminals of the buck-boost circuit.

53. The apparatus of claim 49, wherein the buck-boost circuit is configured to transfer a ripple voltage across the first capacitor to:

a first ripple voltage, across a first of the pair of ripple storage capacitors, fluctuated between an average direct-current voltage at the input terminals of the inverter and twice the average direct-current voltage at the input terminals of the inverter; and

a second ripple voltage, across a second of the pair of ripple storage capacitors, fluctuated between the average direct-current voltage at the input terminals of the inverter and zero voltage.

54. The apparatus of claim 49, wherein the buck-boost circuit comprises two half-legs, each comprising a respective switch connecting a respective one of the pair of ripple storage capacitors across the input terminals of the buck-boost circuit.

55. The apparatus of claim 54, further comprising an inductor, wherein the two half-legs are connected across the input terminals of the buck-boost circuit through the inductor.

56. A method comprising:

converting, with an inverter, direct-current power at an input of the inverter to alternating-current power at an output of the inverter;

filtering a ripple voltage at the input of the inverter by transferring the ripple voltage through a buck-boost circuit connected across the input of the inverter to a pair of ripple storage capacitors.

57. The method of claim 56, further comprising:

swinging, with the buck-boost circuit, the transferred ripple voltage between a first voltage across a first of the pair of ripple storage capacitors and a second voltage across a second of the pair of ripple storage capacitors.

58. The method of claim 56, further comprising:

controlling, with the buck-boost circuit, a first voltage across a first of the pair of ripple storage capacitors to be greater than an average voltage of the direct-current power; and

controlling, with the buck-boost circuit, a second voltage across a second of the pair of ripple storage capacitors to be less than the average voltage of the direct-current power.

59. The method of claim 56, further comprising:

switching, in the buck-boost circuit, a first of the pair of ripple storage capacitors across the input of the inverter through a first switch and an inductor;

switching, in the buck-boost circuit, a second of the pair of ripple storage capacitors across the input of the inverter through a second switch and the inductor.

60. The method of claim 56, further comprising:

fluctuating, across a first of the pair of ripple storage capacitors, a first voltage between an average direct-current voltage at the input of the inverter and twice the average direct-current voltage; and

fluctuating, across a second of the pair of ripple storage capacitors, a second voltage between the average direct-current voltage and zero voltage.