SCALABLE AND REDUNDANT MINI-INVERTERS

• US 20120212065A1
• Filed: 02/15/2012
• Published: 08/23/2012
• Est. Priority Date: 02/15/2011
• Status: Active Grant

• Current Assignee: CyboEnergy, Inc.
• Original Assignee: CyboEnergy, Inc.
• Inventors: CHENG, George Shu-Xing, Mulkey, Steven L.
• Granted Patent: US 9,093,902 B2
• Time in Patent Office: Days
• US Class Current: 307/82
• CPC Class Codes: H02J 2300/26 involving maximum power point tracking control for photovoltaic sources maximum power point systems in particular G05F1/67
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/40 Synchronising a generator for connection to a network or to another generator
• CPC Class Codes: H02J 3/46 Controlling of the sharing of output between the generators, converters, or transformers
• CPC Class Codes: H02J 9/02 in which an auxiliary distribution system and its associated lamps are brought into service
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/325 with means for allowing continuous operation despite a fault, i.e. fault tolerant converters
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop
• CPC Class Codes: Y02B 10/70 Hybrid systems, e.g. uninterruptible or back-up power supplies integrating renewable energies
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

The Scalable and Redundant Mini-inverters as described in this invention include double, triple, or quadruple redundant capabilities so that the Mini-inverters can work in a harsh environment for a prolonged period of time. A number of regular, redundant, triple redundant, or quadruple redundant Mini-inverters with one, two, three, or multiple input channels in a mixed variety can easily connect to one, two, three, or multiple DC power sources such as solar PV modules, invert the DC power to AC power, and daisy chain together to generate AC power to the power grid.

Claims

1. A system for providing AC power to a power grid from a plurality of individual DC power sources each having a DC power output port, comprising:

a) a plurality of power inverters, each of said power inverters being connected to one DC power source, and having an AC power input port and an AC power output port;

b) said AC power output port of each inverter being connected in a daisy chain to the AC power input port of the next inverter, except for the AC power input port of the first inverter being left open, and the AC power output port of the last inverter being connected to a power service panel of the power grid;

c) each of said power inverters including;

i) a main DC-DC boost converter arranged to convert the voltage of said DC power source to a higher DC voltage suitable for inversion;

ii) a backup DC-DC boost converter arranged to convert the voltage of said DC power source to a higher DC voltage suitable for inversion;

iii) a DC input channel selector constructed and arranged to connect the main DC-DC boost converter to said DC power source when the main DC-DC boost converter is working and connect the backup DC-DC boost converter to the DC power source when the main DC-DC boost converter is not working;

iv) a DC power combiner connected to said main DC-DC boost converter and said backup DC-DC boost converter;

v) a DC-AC inverter connected to said DC power combiner and arranged to invert the DC power to AC power with voltage higher than an external AC power voltage from the power grid;

vi) an internal AC powerline that combines the generated AC power with the external AC power from the power grid;

vii) a load interface circuit connected to said DC-AC inverter and to said internal AC powerline, said load interface circuit being arranged to filter high-frequency components out of the said DC-AC inverter'"'"'s AC output;

viii) an MFA microcontroller connected to said main DC-DC boost converter, backup DC-DC boost converter, DC input channel selector, DC-AC inverter, load interface circuit, line sensing circuit, and powerline Modem, said microcontroller arranged to monitor the DC boost voltage, control the DC-DC boost converters, perform maximum power point tracking (MITT), perform DC-AC inversion and AC power synchronization, monitor AC current and voltage for generated power amount and status, perform powerline communications, perform logic controls such as AC powerline switching and isolation, and perform redundancy functions;

ix) a powerline modem connected to said microcontroller and said internal AC powerline through an interface circuitry for transmitting and receiving performance data between said microcontroller and said power grid;

x) a line sensing circuit connected to said internal AC powerline and said microcontroller for detecting the phase and zero-crossing point of the incoming AC power from the power grid;

xi) a solid state switch connected to said internal AC powerline and external AC powerline, and arranged to disconnect said internal AC powerline from the AC grid during the non-generation time; and

xii) a power supply connected to said DC power combiner and arranged to supply DC power to the electronic components of said power inverter.

2. A system for providing AC power to a power grid from a plurality of individual DC power sources each having a DC power output port, comprising:

a) a plurality of power inverters, each of said power inverters being connected to m DC power sources, where m is an integer greater than or equal to two, and having an AC power input port and an AC power output port;

b) said AC power output port of each inverter being connected in a daisy chain to the AC power input port of the next inverter, except for the AC power input port of the first inverter being left open, and the AC power output port of the last inverter being connected to a power service panel of the power grid;

c) each of said power inverters including;

i) m main DC-DC boost converters, each arranged to convert the voltage of a corresponding power source to a higher DC voltage suitable for inversion;

ii) m backup DC-DC boost converters, each arranged to convert the voltage of said corresponding power source to a higher DC voltage suitable for inversion;

iii) m DC input channel selectors, each constructed and arranged to connect its corresponding main DC-DC boost converter to said corresponding DC power source when the corresponding main DC-DC boost converter is working and connect the corresponding backup DC-DC boost converter to the DC power source when the corresponding main DC-DC boost converter is not working;

iv) a DC power combiner connected to said main DC-DC boost converters and said backup DC-DC boost converters;

v) a DC-AC inverter connected to said DC power combiner and arranged to invert the DC power to AC power with voltage higher than an external AC power voltage from the power grid;

vi) an internal AC powerline that combines the generated AC power with the external AC power from the power grid;

vii) a load interface circuit connected to said DC-AC inverter and to said internal AC powerline, said load interface circuit being arranged to filter high-frequency components out of the said DC-AC inverter'"'"'s AC output;

viii) an MFA microcontroller connected to said main DC-DC boost converters, backup DC-DC boost converters, DC input channel selectors, DC-AC inverter, and load interface circuit, said microcontroller arranged to monitor the DC boost voltage, control the DC-DC boost converters, perform maximum power point tracking (MPPT), perform DC-AC inversion and AC power synchronization, monitor AC current and voltage for generated power amount and status, perform powerline communications, perform logic controls such as AC powerline switching and isolation, and perform redundancy functions;

ix) a powerline modem connected to said microcontroller and said internal AC powerline through an interface circuitry for transmitting and receiving performance data between said microcontroller and said power grid;

x) a line sensing circuit connected to said internal AC powerline and said microcontroller for detecting the phase and zero-crossing point of the incoming AC power from the power grid;

xi) a solid state switch connected to said internal AC powerline and external AC powerline, and arranged to disconnect said internal AC powerline from the AC grid during the non-generation time; and

xii) a power supply connected to said DC power combiner and arranged to supply DC power to the electronic components of said power inverter.

3. The system of claim 2, in which the output of each of said power inverters is single-phase AC or three-phase AC.

4. The system of claim 2, in which said MFA microcontroller includes Model-Free Adaptive (MFA) controllers which control the DC-DC boost converters, and MFA optimizers which provide maximum power point tracking (MPPT) to allow the power inverter to achieve optimal power production.

5. A redundant DC- to-AC power inverter, comprising:

a) one AC power output port arranged to supply AC power to the AC power grid;

b) at least one main DC-DC boost converter and a corresponding backup DC-DC boost converter arranged to convert the voltage of a DC power source to a higher DC voltage suitable for inversion;

c) for each main DC-DC boost converter and its corresponding backup DC-DC boost converter, a DC input channel selector constructed and arranged to connect the main DC-DC boost converter to said DC power source when the main DC-DC boost converter is working and connect the corresponding backup DC-DC boost converter to said DC power source when the main DC-DC boost converter is not working;

d) a DC power combiner connected to all main DC-DC boost converters and backup DC-DC boost converters;

e) a DC-AC inverter connected to said DC power combiner and arranged to invert the DC power to AC power with voltage higher than an external AC power voltage from the power grid;

f) an internal AC powerline that combines the generated AC power with the external AC power from the power grid;

g) a load interface circuit connected to said DC-AC inverter and to said internal AC powerline, said load interface circuit being arranged to filter high-frequency components out of the said DC-AC inverter'"'"'s AC output;

h) an MFA microcontroller connected to said main and backup DC-DC boost converters, DC input channel selector, DC-AC inverter, and load interface circuit, said microcontroller arranged to monitor the DC boost voltage, control the DC-DC boost converters, perform maximum power point tracking (MPPT), perform DC-AC inversion and AC power synchronization, monitor AC current and voltage for generated power amount and status, perform powerline communications, perform logic controls such as AC powerline switching and isolation, and perform redundancy functions;

i) a powerline modem connected to said microcontroller and said internal AC powerline through an interface circuitry for transmitting and receiving performance data between said microcontroller and said power grid;

j) a line sensing circuit connected to said internal AC powerline and said microcontroller for detecting the phase and zero-crossing point of the incoming AC power from the power grid;

k) a solid state switch connected to said internal AC powerline and external AC powerline, and arranged to disconnect said internal AC powerline from the AC grid during the non-generation time; and

l) a power supply connected to said DC power combiner and arranged to supply DC power to the electronic components of said power inverter.

8. The inverter of claim 5, in which the output of said inverter is single-phase AC or three-phase AC.

9. The inverter of claim 5, in which said MFA microcontroller includes Model-Free Adaptive (MFA) controllers which control the DC-DC boost converters, and MFA optimizers which provide maximum power point tracking (MPPT) to allow the power inverter to achieve optimal power production.

17. The inverter of claim 5, in which the said MFA microcontroller is programmed with a main program to iteratively:

a) turn on and off the inverter'"'"'s generation circuit based on the DC power source input and conditions of the inverter and AC powerline;

b) calculate the inverter'"'"'s power statistics such as the amount of power generated during a certain period of time;

c) perform diagnostics for the inverter'"'"'s status and operation;

d) run redundancy routine for every input channel;

e) set the inverter'"'"'s unit address;

f) perform powerline communications; and

g) respond to queries from data gathering or acquisition devices to report the power statistics.

18. The inverter of claim 5, in which said MFA microcontroller is further programmed with a redundancy routine to iteratively:

a) monitor said DC-DC boost converter;

b) check the status of said DC-DC boost converter based on the monitoring and a set of test criteria;

c) if the DC-DC boost converter is found to be bad, disconnect DC power to the bad converter by sending proper commands to the input channel selector;

d) disable the bad unit from a converter list saved in a database;

e) activate the next available backup DC-DC boost converter from the converter list;

f) connect DC power to the selected DC-DC boost converter by sending proper commands to the input channel selector; and

g) save and report the DC-DC boost converter redundancy status.

6. A triple-redundant DC- to-AC power inverter, comprising:

a) one AC power output port arranged to supply AC power to the AC power grid;

b) at least one main DC-DC boost converter, a corresponding first-tier backup DC-DC boost converter, and a corresponding second-tier backup DC-DC boost converter arranged to convert the voltage of a DC power source to a higher DC voltage suitable for inversion;

c) for each main DC-DC boost converter and its corresponding first-tier and second-tier backup DC-DC boost converters, a DC input channel selector constructed and arranged to connect the main DC-DC boost converter to said DC power source when the main DC-DC boost converter is working, connect the corresponding first-tier backup DC-DC boost converter to said DC power source when the main DC-DC boost converter is not working, and connect the corresponding second-tier backup DC-DC boost converter to said DC power source when the main DC-DC boost converter and the corresponding first-tier backup DC-DC boost converter are not working;

d) a DC power combiner connected to all main DC-DC boost converters and all first-tier and second-tier backup DC-DC boost converters;

e) a DC-AC inverter connected to said DC power combiner and arranged to invert the DC power to AC power with voltage higher than an external AC power voltage from the power grid;

f) an internal AC powerline that combines the generated AC power with the external AC power from the power grid;

g) a load interface circuit connected to said DC-AC inverter and to said internal AC powerline, said load interface circuit being arranged to filter high-frequency components out of the said DC-AC inverter'"'"'s AC output;

h) an MFA microcontroller connected to said main and backup DC-DC boost converters, DC input channel selector, DC-AC inverter, and load interface circuit, said microcontroller arranged to monitor the DC boost voltage, control the DC-DC boost converters, perform maximum power point tracking (MPPT), perform DC-AC inversion and AC power synchronization, monitor AC current and voltage for generated power amount and status, perform powerline communications, perform logic controls such as AC powerline switching and isolation, and perform redundancy functions;

i) a powerline modem connected to said microcontroller and said internal AC powerline through an interface circuitry for transmitting and receiving performance data between said microcontroller and said power grid;

j) a line sensing circuit connected to said internal AC powerline and said microcontroller for detecting the phase and zero-crossing point of the incoming AC power from the power grid;

k) a solid state switch connected to said internal AC powerline and external AC powerline, and arranged to disconnect said internal AC powerline from the AC grid during the non-generation time; and

l) a power supply connected to said DC power combiner and arranged to supply DC power to the electronic components of said power inverter.

7. A quadruple-redundant DC- to-AC power inverter, comprising:

a) one AC power output port arranged to supply AC power to the AC power grid;

b) at least one main DC-DC boost converter, a corresponding first-tier backup DC-DC boost converter, a corresponding second-tier backup DC-DC boost converter, and a corresponding third-tier backup DC-DC boost converter arranged to convert the voltage of a DC power source to a higher DC voltage suitable for inversion;

c) for each main DC-DC boost converter and its corresponding first-tier, second-tier, and third-tier backup DC-DC boost converters, a DC input channel selector constructed and arranged to connect the main DC-DC boost converter to said DC power source when the main DC-DC boost converter is working;

connect the corresponding first-tier backup DC-DC boost converter to said DC power source when the main DC-DC boost converter is not working;

connect the corresponding second-tier backup DC-DC boost converter to said DC power source when the main DC-DC boost converter and the corresponding first-tier backup DC-DC boost converter are not working; and

connect the corresponding third-tier backup DC-DC boost converter to said DC power source when the main DC-DC boost converter and the corresponding first-tier and corresponding second-tier backup DC-DC boost converters are not working;

d) a DC power combiner connected to all main DC-DC boost converters and all first-tier, second-tier and third-tier backup DC-DC boost converters;

e) a DC-AC inverter connected to said DC power combiner and arranged to invert the DC power to AC power with voltage higher than an external AC power voltage from the power grid;

f) an internal AC powerline that combines the generated AC power with the external AC power from the power grid;

g) a load interface circuit connected to said DC-AC inverter and to said internal AC powerline, said load interface circuit being arranged to filter high-frequency components out of the said DC-AC inverter'"'"'s AC output;

h) an MFA microcontroller connected to said main and backup DC-DC boost converters, DC input channel selector, DC-AC inverter, and load interface circuit, said microcontroller arranged to monitor the DC boost voltage, control the DC-DC boost converters, perform maximum power point tracking (MPPT), perform DC-AC inversion and AC power synchronization, monitor AC current and voltage for generated power amount and status, perform powerline communications, perform logic controls such as AC powerline switching and isolation, and perform redundancy functions;

i) a powerline modem connected to said microcontroller and said internal AC powerline through an interface circuitry for transmitting and receiving performance data between said microcontroller and said power grid;

j) a line sensing circuit connected to said internal AC powerline and said microcontroller for detecting the phase and zero-crossing point of the incoming AC power from the power grid;

k) a solid state switch connected to said internal AC powerline and external AC powerline, and arranged to disconnect said internal AC powerline from the AC grid during the non-generation time; and

l) a power supply connected to said DC power combiner and arranged to supply DC power to the electronic components of said power inverter.

10. A scalable DC to AC power inversion system for providing AC power to a power grid from a plurality of individual DC power sources each having a DC power output port, comprising:

a) a plurality of power inverters, each of said power inverters having an AC input port, an AC output port, a main DC-DC boost converter, at least one backup DC-DC boost converter, a DC input channel selector constructed and arranged to connect the main DC-DC boost converter to a DC power source when the main DC-DC boost converter is working and connect the backup DC-DC boost converter to the DC power source when the main DC-DC boost converter is not working, and a DC power combiner connected to said main DC-DC boost converter and said backup DC-DC boost converter;

b) said AC power output port of each inverter being connected in a daisy chain to the AC power input port of the next inverter, except for the AC power input port of the first inverter being left open, and the AC power output port of the last inverter being connected to a power service panel of the power grid; and

c) whereby said system is incrementally scalable by adding or subtracting DC power sources and daisy-chained inverters.

11. The system of claim 10, in which the output of each of said power inverters is single-phase AC or three-phase AC.

12. The system of claim 10, wherein each of the said power inverters comprises:

a) one AC power output port arranged to supply AC power to the AC power grid;

b) at least one main DC-DC boost converter and a corresponding backup DC-DC boost converter arranged to convert the voltage of a DC power source to a higher DC voltage suitable for inversion;

c) for each main DC-DC boost converter and its corresponding backup DC-DC boost converter, a DC input channel selector constructed and arranged to connect the main DC-DC boost converter to said DC power source when the main DC-DC boost converter is working and connect the corresponding backup DC-DC boost converter to said DC power source when the main DC-DC boost converter is not working;

d) a DC power combiner connected to all main DC-DC boost converters and backup DC-DC boost converters;

e) a DC-AC inverter connected to said DC power combiner and arranged to invert the DC power to AC power with voltage higher than an external AC power voltage from the power grid;

f) an internal AC powerline that combines the generated AC power with the external AC power from the power grid;

g) a load interface circuit connected to said DC-AC inverter and to said internal AC powerline, said load interface circuit being arranged to filter high-frequency components out of the said DC-AC inverter'"'"'s AC output;

h) an MFA microcontroller connected to said main and backup DC-DC boost converters, DC input channel selector, DC-AC inverter, and load interface circuit, said microcontroller arranged to monitor the DC boost voltage, control the DC-DC boost converters, perform maximum power point tracking (MPPT), perform DC-AC inversion and AC power synchronization, monitor AC current and voltage for generated power amount and status, perform powerline communications, perform logic controls such as AC powerline switching and isolation, and perform redundancy functions;

i) a powerline modem connected to said microcontroller and said internal AC powerline through an interface circuitry for transmitting and receiving performance data between said microcontroller and said power grid;

j) a line sensing circuit connected to said internal AC powerline and said microcontroller for detecting the phase and zero-crossing point of the incoming AC power from the power grid;

k) a solid state switch connected to said internal AC powerline and external AC powerline, and arranged to disconnect said internal AC powerline from the AC grid during the non-generation time; and

l) a power supply connected to said DC power combiner and arranged to supply DC power to the electronic components of said power inverter.

13. A method of making a DC to AC power conversion system incrementally scalable, comprising:

a) providing a plurality of DC power sources and a plurality of DC to AC power inverters, said inverters each having an AC input port, an AC output port, a main DC-DC boost converter, at least one backup DC-DC boost converter, a DC input channel selector constructed and arranged to connect the main DC-DC boost converter to a DC power source when the main DC-DC boost converter is working and connect the backup DC-DC boost converter to the DC power source when the main DC-DC boost converter is not working, and a DC power combiner connected to said main DC-DC boost converter and said backup DC-DC boost converter;

b) connecting at least one of said DC power sources, respectively, to at least one of said DC to AC power inverters; and

c) producing AC power.

14. The method of claim 13, further comprising:

a) daisy-chaining at least two of said inverters, said AC power output port of each inverter being connected in a daisy chain to the AC power input port of the next inverter, except for the AC power input port of the first inverter being left open, and the AC power output port of the last inverter being connected to a power service panel of the power grid; and

b) producing a total AC power that is the summation of the AC power supplied by each said inverter.

15. The method of claim 13, in which the output of each of said power inverters is single-phase AC or three-phase AC.

16. The method of claim 13, wherein each of the said power inverters further comprises:

a) one AC power output port arranged to supply AC power to the AC power grid;

b) at least one main DC-DC boost converter and a corresponding backup DC-DC boost converter arranged to convert the voltage of a DC power source to a higher DC voltage suitable for inversion;

c) for each main DC-DC boost converter and its corresponding backup DC-DC boost converter, a DC input channel selector constructed and arranged to connect the main DC-DC boost converter to said DC power source when the main DC-DC boost converter is working and connect the corresponding backup DC-DC boost converter to said DC power source when the main DC-DC boost converter is not working;

d) a DC power combiner connected to all main DC-DC boost converters and backup DC-DC boost converters;

e) a DC-AC inverter connected to said DC power combiner and arranged to invert the DC power to AC power with voltage higher than an external AC power voltage from the power grid;

f) an internal AC powerline that combines the generated AC power with the external AC power from the power grid;

g) a load interface circuit connected to said DC-AC inverter and to said internal AC powerline, said load interface circuit being arranged to filter high-frequency components out of the said DC-AC inverter'"'"'s AC output;

h) an MFA microcontroller connected to said main and backup DC-DC boost converters, DC input channel selector, DC-AC inverter, and load interface circuit, said microcontroller arranged to monitor the DC boost voltage, control the DC-DC boost converters, perform maximum power point tracking (MPPT), perform DC-AC inversion and AC power synchronization, monitor AC current and voltage for generated power amount and status, perform powerline communications, perform logic controls such as AC powerline switching and isolation, and perform redundancy functions;

i) a powerline modem connected to said microcontroller and said internal AC powerline through an interface circuitry for transmitting and receiving performance data between said microcontroller and said power grid;

j) a line sensing circuit connected to said internal AC powerline and said microcontroller for detecting the phase and zero-crossing point of the incoming AC power from the power grid;

k) a solid state switch connected to said internal AC powerline and external AC powerline, and arranged to disconnect said internal AC powerline from the AC grid during the non-generation time; and

l) a power supply connected to said DC power combiner and arranged to supply DC power to the electronic components of said power inverter.