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US 2022/0103092 A1Published application
Dc-ac inverter drive system and operation
AssigneeKripya LLC
InventorsVilakkudi G. Veeraraghavan, Ramarao Ananathakrishnan, Murali Thangaraj, Asif Ismail
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Abstract
Disclosed is a drive system and its operation for multiple DC-AC inverters working in parallel, for applications such as off-grid solar energy harvesting, which enables a stable operation under various load conditions. The disclosed drive system offers voltage and frequency synchronized sine wave output from each of the inverters, enabling stable operation of the entire system under differing load conditions.
Claims20
A direct current-to-alternating current (DC-AC) inverter system operating in off-grid mode comprising:
- multiple direct current (DC) sources;
- a first DC-AC inverter coupled to a first DC source of the multiple DC sources and configured to generate a first alternating current (AC) output voltage, wherein the first DC-AC inverter is configured as a control unit for establishing a reference output voltage and a reference output frequency, the first DC-AC inverter comprising:
- a power converter subsystem;
- and
- a controller subsystem comprising:
- a pulse-width modulation (PWM) module configured to generate a reference PWM signal and PWM drive signals at a switching frequency of the power converter subsystem;
- and
- a first communication port to transmit a reference PWM signal, a PWM synchronization signal and a zero crossing synchronization signal to a second DC-AC inverter;
- and
- the second DC-AC inverter coupled to a second DC source of the multiple DC sources and configured to generate a second AC output voltage, wherein the second DC-AC inverter is configured as a follower unit, the second DC-AC inverter comprising a second communication port to receive the reference PWM drive signal and the one or more synchronization signals from the first DC-AC inverter.
7 more elements
A method of operating a direct current-to-alternating current (DC-AC) inverter system in off-grid mode, the method comprising:
- coupling multiple direct current (DC) sources to an array of DC-AC inverters configured to generate alternating current (AC) output voltage;
- configuring a first DC-AC inverter in the array as a control unit;
- configuring one or more second DC-AC inverters in the array as one or more follower units;
- establishing a reference output voltage and a reference output frequency by the first DC-AC inverter;
- generating, by a pulse-width modulation (PWM) module in a controller subsystem of the first DC-AC inverter and using a closed-loop control algorithm, a reference PWM signal and first PWM drive signals at a switching frequency of a power converter subsystem of the first DC-AC inverter;
- using the first PWM drive signals for driving first power switches in a first DC-AC converter of the first DC-AC inverter;
- sending the reference PWM signal, a PWM synchronization signal, and a zero crossing synchronization signal through a communication port of the first DC-AC inverter to the one or more second DC-AC inverters;
- receiving, by the one or more second DC-AC inverters, the reference PWM signal, the PWM synchronization signal, and the zero crossing synchronization signal;
- capturing a duty cycle of the reference PWM signal;
- generating second PWM drive signals by replication by one or more second PWM modules of the one or more second DC-AC inverters;
- and
- using the second PWM drive signals for driving second power switches in one or more second DC-AC converters of the one or more second DC-AC inverters.
9 more elements
A direct current-to-alternating current (DC-AC) inverter system operating in off-grid mode comprising:
- multiple direct current (DC) sources;
- a first DC-AC inverter coupled to a first DC source of the multiple DC sources and configured to generate a first alternating current (AC) output voltage, wherein the first DC-AC inverter is configured as a control unit for establishing a reference output voltage and a reference output frequency, the first DC-AC inverter comprising:
- a first power converter subsystem comprising first power switches;
- and
- a controller subsystem comprising:
- a pulse-width modulation (PWM) module configured to generate PWM drive signals at a switching frequency of the first power converter subsystem for driving the first power switches;
- and
- a first communication port configured to transmit the PWM drive signals to a second DC-AC inverter in the system;
- and
- the second DC-AC inverter coupled to a second DC source of the multiple DC sources and configured to generate a second AC output voltage, wherein the second DC-AC inverter is configured as a follower unit, the second DC-AC inverter configured to receive the PWM drive signals from the first DC-AC inverter, to drive second power switches of a second power converter subsystem of the second DC-AC inverter.
7 more elements
Dependencies are inferred from the claim text.