Direct Current Link Circuit

• US 20140084894A1
• Filed: 09/23/2013
• Published: 03/27/2014
• Est. Priority Date: 09/12/2011
• Status: Active Grant

• Current Assignee: Solaredge Technologies Incorporated
• Original Assignee: Solaredge Technologies Incorporated
• Inventors: Lubomirsky, Vadim
• Granted Patent: US 10,396,662 B2
• Time in Patent Office: Days
• US Class Current: 323/299
• CPC Class Codes: H02J 2300/10 The dispersed energy generation being of fossil origin, e.g. diesel generators
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02M 3/1563 without using an external clock H02M3/158 takes precedence
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A device for converting power from a floating source of DC power to a dual direct current (DC) output, the device includes: positive and negative input terminals connectible to the floating source of DC power; and positive and negative, and ground output terminals connectible to the dual DC output that may feed an inverter. The inverter may be either a two or three level inverter. A charge storage device may be connected in parallel to, and charged from, the positive and negative input terminals. A resonant circuit may be also connected between the charge storage device and the dual DC output. The resonant circuit may include an inductor connected in series with a capacitor. The charge storage device may discharge through the resonant circuit by switching through to either the negative output terminal or the positive output terminal.

Claims

1. A method comprising:

connecting, through a resonant circuit, a direct current power source alternatively across;

a positive output terminal of a dual direct current output and a neutral terminal during a first portion of a switching cycle; and

a negative output terminal of the dual direct current output and the neutral terminal during a second portion of a switching cycle.

2. The method of claim 1, wherein the direct current power source is floating relative to the neutral terminal during transitions between the first portion and the second portion of the switching cycle.

3. The method of claim 1, wherein the switching cycle occurs periodically at a resonant frequency of the resonant circuit.

4. The method of claim 3, wherein the resonant frequency of the switching cycle results in current being substantially zero through switches providing the connecting during transitions between the first portion and the second portion of the switching cycle.

5. The method of claim 1, comprising:

charging a first charge storage device connected across the positive output terminal and the neutral terminal during the first portion of a switching cycle; and

charging a second charge storage device connected across the negative output terminal and the neutral terminal during the second portion of a switching cycle.

6. The method of claim 5, wherein the resonant circuit includes the first charge storage device, second charge storage device, and an inductor connected between the neutral terminal and switches providing the connecting.

7. The method of claim 6, wherein the connecting includes:

closing a first one of the switches connected between the inductor and a positive source terminal of the direct current power source during the first portion of the cycle;

opening the first one of the switches during the second portion of the cycle;

opening a second one of the switches connected between the inductor and a negative source terminal of the direct current power source during the first portion of the cycle; and

closing the second one of the switches during the second portion of the cycle.

8. The method of claim 1, wherein the first portion of the switching cycle occurs within a first half of a period of the resonant circuit and the second portion of the switching cycle occurs within a second half of the period of the resonant circuit.

9. The method of claim 1, providing power from the direct current power source to an inverter connected to the dual direct current output, wherein the direct current power source includes a solar panel.

10. The method of claim 1, wherein the first portion and the second portion of the switching cycle are each less than 50% of a period of the resonant circuit.

11. An apparatus comprising:

input terminals including a positive input terminal and a negative input terminal;

output terminals including a positive output terminal and a negative output terminal;

a resonant circuit; and

switches adapted to connect, through the resonant circuit, the input terminals alternatively across;

the positive output terminal and a neutral node during a first portion of a switching cycle; and

the negative output terminal and the neutral node during a second portion of the switching cycle.

12. The apparatus of claim 11, wherein the input terminals are floating relative to the neutral node during transitions between the first portion and the second portion of the switching cycle.

13. The apparatus of claim 11, wherein the switching cycle occurs periodically at a resonant frequency of the resonant circuit.

14. The apparatus of claim 13, wherein the resonant frequency of the switching cycle causes current through the switches being substantially zero when the switches are toggling between open and closed states.

15. The apparatus of claim 11, wherein the resonant circuit comprises:

a first charge storage device connected across the positive output terminal and neutral node;

a second charge storage device connected across the negative output terminal and the neutral node; and

an inductor connected between the switches and the neutral node.

16. The apparatus of claim 15, wherein the switches include a first switch connected between the inductor and the positive input terminal and a second switch connected between the inductor and the negative input terminal.

17. The apparatus of claim 16, comprising:

a first diode including an anode connected to the negative output terminal and a cathode connected to the negative input terminal.

a second diode with a cathode connected to the positive output terminal and an anode connected to the positive input terminal.

18. The apparatus of claim 11, wherein the switches are adapted to toggle at the switching cycle that is substantially at a resonant frequency of the resonant circuit, and wherein the first portion and the second portion of the switching cycle are each less than 50% of a period of the resonant frequency.

19. The apparatus of claim 11, comprising an inverter having an inverter input connected to the output terminals.

20. The apparatus of claim 11, comprising a solar panel having a direct current output connected to the input terminals.