Grid-tie inverter with active power factor correction
AssigneeThe Aerospace Corporation
InventorKasemsan Siri
Life of this patent
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Abstract
A grid-tie inverter (the “inverter”) may include a power converter that receives a direct current (DC) output voltage from a DC input power source, and generates an alternating current (AC) output voltage for transmission to a utility power grid. The inverter may also include a system controller that regulates the AC output voltage to efficiently transfer power to the utility power grid while a system AC load may be terminated across the output of the inverter. The inverter may also provide active power factor correction between the utility grid voltage and current. Furthermore, the inverter may also offer harmonic cancellation, which minimizes or eliminates the harmonic content out of the utility power grid voltage and current.
Claims25
An apparatus, comprising:
- a power converter configured to receive a direct current (DC) output voltage from a DC input power source, and generate an alternating current (AC) output voltage for transmission to a utility power grid, a grid-interface circuit, or a set of parallel-connected AC loads;
- and
- a system controller configured to regulate the AC output voltage to efficiently transfer power to the utility power grid and to ensure a zero DC value of an AC output current of the power converter, wherein
- the system controller is further configured to
- control an AC current of the utility grid to be out-of-phase with respect to a voltage of the utility power grid when a load consumes power exceeding a maximum power of the DC input power source or a rated limiting power of the apparatus, and
- control the AC current of the utility grid to be in-phase with respect to the voltage of the utility power grid when the load consumes less power than a delivered output power of the power converter.
An apparatus for active power correction, comprising:
- a switching network configured to:
- produce a positive output voltage for a period that is longer than that of a negative output voltage to cause an inverter to deliver a positive voltage, or
- produce the positive output voltage for a period that is shorter than that of the negative output voltage to cause the inverter to deliver a negative voltage;
- a steering logic pulse with modulation (PWM) switching driver configured to convert a PWM switching signal to be a set of switching signals that drive the switching network;
- and
- a phase-controlled reference SINE-WAVE generator configured to process a phase control signal and a utility grid voltage and produce a commanding reference signal and a reference co-sinusoidal voltage, wherein
- the reference co-sinusoidal voltage possesses a 90 degree phase lead with respect to the utility grid voltage.
Dependencies are inferred from the claim text.