Dual mode DC-AC inverter system and operation
First Claim
1. A dual mode direct current-to-alternating current (DC-AC) inverter comprising:
- a DC-AC converter to convert direct current (DC) voltage into alternating current (AC) voltage output; and
a controller subsystem comprising a mode selector to select between operating the DC-AC inverter in at least one of;
(i) a current control mode upon receipt of an indication that active external AC power is available, or (ii) a power control mode upon receipt of an indication that active external AC power is unavailable.
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Accused Products
Abstract
A dual mode direct current-to-alternating current (DC-AC) inverter is capable of operating either with or without connection to an active external AC power source. The dual mode DC-AC inverter may operate in “current control mode” when connection to the active AC power source is present and may operate in “power control mode” when connection to the active external AC source is absent. Processes for operating an array of these DC-AC inverters are disclosed. The dual mode operation capability enables the DC-AC inverters to function both in the grid connected mode (i.e., current control mode) as well as off-grid mode (i.e., power control mode). The system is configured to sense the presence or absence of grid power and automatically select the appropriate mode of operation. For the power control mode of operation, a process may include designating a master from the array of DC-AC inverters in order to establish the voltage and frequency reference.
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Citations
19 Claims
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1. A dual mode direct current-to-alternating current (DC-AC) inverter comprising:
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a DC-AC converter to convert direct current (DC) voltage into alternating current (AC) voltage output; and a controller subsystem comprising a mode selector to select between operating the DC-AC inverter in at least one of;
(i) a current control mode upon receipt of an indication that active external AC power is available, or (ii) a power control mode upon receipt of an indication that active external AC power is unavailable. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of operating a dual mode direct current-to-alternating current (DC-AC) inverter comprising:
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converting direct current (DC) voltage into alternating current (AC) voltage; receiving an indication that external AC power is either available or unavailable; and in response to the receiving the indication, selecting between; operating the dual mode DC-AC inverter in a current control mode upon determining that the external AC power is available; and operating the dual mode DC-AC inverter in a power control mode upon determining that the external AC power is unavailable. - View Dependent Claims (8)
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9. A method of operating an array of dual mode direct current-to-alternating current (DC-AC) inverters in response to a connection to an external alternating current (AC) power source being absent or not active, the method comprising:
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designating a dual mode DC-AC inverter in the array as a master inverter; establishing a reference output power value, a reference output voltage, and a reference output frequency using the master inverter; applying the reference output voltage at the reference output frequency of the master inverter to an AC bus; and operating remaining ones of the dual mode DC-AC inverters in the array in power control mode to substantially match respective output voltages and output frequencies of the remaining ones of the dual mode DC-AC inverters with the reference output voltage and the reference output frequency present in the AC bus. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A dual mode direct current-to-alternating current (DC-AC) inverter configured to operate in power control mode in response to a connection to an external alternating current (AC) power source being absent or not active, the dual mode DC-AC inverter comprising a power control algorithm to:
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set a reference power limit for the dual mode DC-AC inverter; synthesize a reference voltage and a reference frequency based on a function or a table; regulate an output power of the dual mode DC-AC inverter based at least in part on the reference power limit; and substantially match an output voltage and an output frequency of the dual mode DC-AC inverter to the reference voltage and the reference frequency.
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Specification