Apparatus and method for controlling a power inverter
First Claim
1. A method for controlling an inverter configured to deliver power from a direct current (DC) alternative energy source to an alternating current (AC) grid at a grid voltage and a grid phase, the inverter including an input converter coupled to an output converter via a DC bus, the method comprising:
- determining a first amount of power being supplied by the DC alternative energy source; and
in response to the first amount of power being less than a predetermined amount of power;
(i) disabling the output converter of the inverter,(ii) in response to the AC grid voltage crossing zero volts, determining an estimated DC bus voltage for a future zero-crossing of the AC grid voltage and determining minimum DC bus voltage, and(iii) in response to the estimated DC bus voltage being greater than a predetermined maximum DC bus voltage, enabling the output converter of the inverter to transfer energy from the DC bus to the AC grid such that the DC bus voltage is reduced to approximately the minimum DC bus voltage.
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Accused Products
Abstract
An apparatus and method for controlling a DC-to-AC inverter is disclosed. The DC-to-AC inverter may be configured to convert DC power received from an alternative energy source to AC power for supplying an AC grid or load. The inverter may determine whether the power presently supplied by the alternative energy source is less than a predetermined amount of power and, if so, disable an output converter of the inverter. Additionally, the inverter may predict the voltage of a DC bus of the inverter at a future point in time and, if the predicted DC bus voltage is greater than a predetermined maximum DC bus voltage, enable the output converter to transfer energy from the DC bus to the AC grid to reduce the DC bus voltage.
199 Citations
28 Claims
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1. A method for controlling an inverter configured to deliver power from a direct current (DC) alternative energy source to an alternating current (AC) grid at a grid voltage and a grid phase, the inverter including an input converter coupled to an output converter via a DC bus, the method comprising:
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determining a first amount of power being supplied by the DC alternative energy source; and in response to the first amount of power being less than a predetermined amount of power; (i) disabling the output converter of the inverter, (ii) in response to the AC grid voltage crossing zero volts, determining an estimated DC bus voltage for a future zero-crossing of the AC grid voltage and determining minimum DC bus voltage, and (iii) in response to the estimated DC bus voltage being greater than a predetermined maximum DC bus voltage, enabling the output converter of the inverter to transfer energy from the DC bus to the AC grid such that the DC bus voltage is reduced to approximately the minimum DC bus voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An inverter to deliver power from a direct current (DC) alternative energy source to an alternating current (AC) grid at a grid voltage and a grid phase, the inverter comprising:
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an input converter eclectically coupled to the DC alternative energy source; an output converter electrically coupled to the AC grid; a DC bus coupled to the input converter and the output converter; and a control circuit electrically coupled to the input converter and the output converter, the control circuit to; determine a first amount of power being supplied by the DC alternative energy source; and in response to the first amount of power being less than a predetermined amount of power; (i) disable the output converter, (ii) in response to the AC grid voltage crossing zero volts, determine an estimated DC bus voltage for a future zero-crossing of the AC grid voltage and determine minimum DC bus voltage, and (iii) in response to the estimated DC bus voltage being greater than a predetermined maximum DC bus voltage, enable the output converter of the inverter to transfer energy from the DC bus to the AC grid such that the DC bus voltage is reduced to approximately the minimum DC bus voltage. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. An apparatus comprising:
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a solar panel comprising a solar cell configured to generate a first direct current (DC) waveform in response to receiving an amount of sunlight; an inverter coupled to the solar cell panel and configured to receive the first DC waveform and convert the first DC waveform to an output alternating current (AC) waveform supplied to an AC grid, the inverter comprising; an input converter electrically coupled the solar cell and a DC bus, the input converter configured to convert the first DC waveform to a second DC waveform supplied to the DC bus; an output converter electrically coupled to the DC bus and configured to convert the second DC waveform to the output AC waveform at an AC grid voltage and frequency; and a control circuit electrically coupled to the input converter and the output converter, the control circuit to; determine a first amount of power being supplied by the DC alternative energy source; and in response to the first amount of power being less than a predetermined amount of power; (i) disable the output converter, (ii) in response to the AC grid voltage crossing zero volts, determine an estimated DC bus voltage for a future zero-crossing of the AC grid voltage and determine minimum DC bus voltage, and (iii) in response to the estimated DC bus voltage being greater than a predetermined maximum DC bus voltage, enable the output converter of the inverter to transfer energy from the DC bus to the AC grid such that the DC bus voltage is reduced to approximately the minimum DC bus voltage.
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Specification