Inverter for use with solar arrays

• US 4,591,965 A
• Filed: 10/19/1984
• Issued: 05/27/1986
• Est. Priority Date: 10/19/1984
• Status: Expired due to Fees

• Current Assignee: Arthur F. Dickerson
• Original Assignee: Arthur F. Dickerson
• Inventors: Dickerson, Arthur F.
• Primary Examiner(s): Leung, Philip H.
• Application Number:
  US06/662,783
• Time in Patent Office: 585 Days
• Field of Search: 363/43, 363/40, 363/97, 363/98, 363/131, 363/132, 323/906, 307/260
• US Class Current: 363/43
• CPC Class Codes: H02M 7/49 Combination of the output voltage waveforms of a plurality of converters
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y10S 323/906 Solar cell systems

Abstract

A controlled switching system for converting the output of several photovoltaic solar arrays into a polyphase alternating electric current. Each array is utilized 100% of the time, and at any particular instant only one array or no array is feeding a particular phase. The specific line to which an array is connected is altered in a cyclic manner by the switching system to synthesize the polyphase current. Energy is not stored in the switching system, but instead is made available as polyphase electric current as soon as it is generated by the photovoltaic arrays. Each phase approximates a sine wave to an extent that is limited by the number of arrays. For the closest approximation, the arrays must be configured to have prescribed voltages and currents. Alternatively, a single array may be partitioned electrically in such a way that the desired voltages and currents are attained.

Claims

1. In a system for generating an N phase alternating electric current by using switching means controlled by a controller to intermittently connect a number M of solar arrays (listed in order of decreasing output voltage as D₁, D₂, . . . D_i . . . D_M) to the lines L₁, L₂, . . . L_k . . . L_N where N is an odd number equal to or greater than M, the improvement comprising:

control means for controlling the switching means to connect D_i to L_k in a positive sense for an interval of duration 90°

/N beginning at ##EQU10## where δ

is any constant angle, and for controlling the switching means to connect D_i to L_k in a negative sense for an interval of duration 90°

/N beginning at ##EQU11## for all values of i and k, where 1<

i≦

M and 1<

k≦

N, whereby at any particular instant no more than one array is feeding a particular line, and whereby each array is utilized 100% of the time.

2. The improvement of claim 1 wherein N=3.

3. The improvement of claim 2 wherein M=3.

4. The improvement of claim 2 wherein M=2.

5. In a system for generating a 2N-phase electric current by switching means controlled by a controller to intermittently connect M pairs of solar arrays, each pair consisting of two identical arrays and listed in order of decreasing output voltage as (D₁, D₁ '"'"') . . . (D_i, D_i '"'"') . . . (D_M, D_M '"'"') where 1≦

i≦

M and where each array has a positive terminal and a negative terminal, to the lines L_l, . . . L_k, . . . L_N and to the lines L_l '"'"', . . . L_k '"'"' . . . L_N '"'"', where 1≦

k≦

N and where 1≦

M≦

N, the improvement comprising;

grounding means connecting the negative terminals of D₁, D₂, . . . D_M and the positive terminals of D₁ '"'"', D₂ '"'"' . . . D_M '"'"' to ground; and

,

control means for controlling the switching means to connect the positive terminal of D_i to L_k and simultaneously to connect the negative terminal of D_i '"'"' to L_k '"'"' for an interval of 90°

/N beginning at ##EQU12## and for controlling the switching means to connect the negative terminal of D_i '"'"' to L_k and simultaneously to connect the positive terminal of D_i to L_k '"'"' for an interval of 90°

/N beginning at ##EQU13## for all values of i and k, where 1≦

i≦

M and 1≦

k≦

N and where δ

is any constant angle, whereby at any particular instant no more than one array is feeding a particular line, and whereby each array is utilized 100% of the time.

6. The improvement of claim 5 wherein N=3.

7. The improvement of claim 6 wherein M=3.

8. The improvement of claim 6 wherein M=2.

9. The improvement of claim 6 wherein M=1.

10. The improvement of claim 5 wherein N=6.

11. The improvement of claim 10 wherein M=6.

12. The improvement of claim 10 wherein M=5.

13. The improvement of claim 10 wherein M=4.

14. The improvement of claim 10 wherein M=3.

15. The improvement of claim 10 wherein M=2.

16. The improvement of claim 10 wherein M=1.