DUAL MODE MICRO-INVERTER SYSTEM AND OPERATION
First Claim
1. A dual mode direct current-to-alternating current (DC-AC) micro-inverter comprising:
- a DC-AC converter to convert direct current (DC) voltage into alternating current (AC) voltage output; and
a microcontroller comprising a mode selector to select between operating the DC-AC micro-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 voltage 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) micro-inverter is capable of operating either with or without connection to an active external AC power source. The dual mode DC-AC micro-inverter may operate in “current control mode” when connection to the active AC power source is present and may operate in “voltage control mode” when connection to the active external AC source is absent. Processes for operating an array of these micro-inverters are disclosed. The dual mode operation capability enables the micro-inverter(s) to function both in the grid connected mode (i.e., current control mode) as well as off-grid mode (i.e., voltage 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 voltage control mode of operation, a process may include designating a master from the array of micro-inverters in order to establish the voltage and frequency references.
22 Citations
20 Claims
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1. A dual mode direct current-to-alternating current (DC-AC) micro-inverter comprising:
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a DC-AC converter to convert direct current (DC) voltage into alternating current (AC) voltage output; and a microcontroller comprising a mode selector to select between operating the DC-AC micro-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 voltage 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) micro-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 micro-inverter in a current control mode upon determining that the external AC power is available; and operating the dual mode DC-AC micro-inverter in a voltage control mode upon determining that the external AC power is unavailable. - View Dependent Claims (8)
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9. A dual mode direct current-to-alternating current (DC-AC) micro-inverter configured to operate in current control mode when a connection to an active external alternating current (AC) power source is present, the dual mode DC-AC micro-inverter comprising a current control algorithm to:
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calculate an output current based at least in part on available direct current (DC) input power and a voltage of the active external AC power source; and synchronize the voltage and frequency associated with the output current with the voltage and frequency of the active external AC power source.
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10. A dual mode direct current-to-alternating current (DC-AC) micro-inverter configured to operate in voltage control mode when a connection to an external alternating current (AC) power source is absent or not active, the dual mode DC-AC micro-inverter comprising a voltage control algorithm to:
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synthesize a reference voltage and a reference frequency based on a built in function or a table; and regulate an output voltage of the dual mode DC-AC micro-inverter to substantially match the reference voltage and the reference frequency.
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11. A method of operating an array of dual mode direct current-to-alternating current (DC-AC) micro-inverters when a connection to an external alternating current (AC) power source is absent or not active, the method comprising:
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designating a micro-inverter in the array as a master micro-inverter; establishing a reference output voltage and a reference output frequency using the master micro-inverter; and operating remaining ones of the micro-inverters in the array in voltage control mode to synchronize respective output voltages and output frequencies of the remaining ones of the micro-inverters with the reference output voltage and the reference output frequency. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification