Parallel Inverter Device Autonomous Phase Control
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Solution Overview
Problem
Existing parallel inverter devices require control lines for accurate operation when connected in parallel, leading to signal delays and limitations on the number of connectable devices, especially when dealing with varying AC voltage and frequency magnitudes or phase shifts, which complicates the parallel operation and restricts scalability.
Innovation Solution
A parallel inverter device configuration that uses two MOSFETs in series on the output line with opposite energization directions, controlled by a controller based on AC voltage polarity and current direction, eliminating the need for control lines by interrupting cross currents and adjusting phase and voltage differences autonomously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If control lines are used to connect inverter devices for parallel operation, then accurate control of AC voltage magnitude and timing is achieved, but signal delay occurs and the number of connectable devices is limited
Solution Approach 1:
The patent extracts and eliminates the control line from the parallel inverter system. Each inverter device independently detects AC voltage parameters and controls its own switching elements without requiring communication with other devices, thereby removing the source of signal delay while maintaining control accuracy through autonomous operation.
Solution Approach 2:
Each inverter device performs self-control by independently detecting AC voltage magnitude and timing, and autonomously adjusting its switching elements to prevent cross currents. This self-service mechanism eliminates dependency on external control lines and enables unlimited parallel connections without signal delay.
2Reliability
If control lines are used to connect inverter devices, then cross current is suppressed, but device complexity increases and scalability is restricted
Solution Approach 1:
The control line is completely removed from the system architecture. Instead of using external communication paths, each inverter device incorporates internal detection and control circuits that directly monitor AC voltage parameters and adjust switching elements locally, simplifying the overall system while maintaining cross current suppression.
Solution Approach 2:
The control function is segmented and distributed to each individual inverter device rather than being centralized through control lines. Each device independently performs detection and control operations, transforming a centralized control architecture into a distributed autonomous architecture that reduces complexity and enables scalability.
3Power
If the number of parallel inverter devices is increased, then power capacity is expanded, but control line length increases causing signal delay
Solution Approach 1:
The control line infrastructure is extracted and removed entirely. Power capacity expansion is achieved by simply adding more inverter devices in parallel without any increase in control line length, since each device operates autonomously and does not require communication paths to other devices or a central controller.
Solution Approach 2:
The system transitions from a static control architecture with fixed control lines to a dynamic autonomous architecture where each device independently adapts to operating conditions. This dynamic self-control enables unlimited scalability as devices can be added or removed without affecting control line configuration or signal timing.
Data Source
AI summary
Provided is a parallel inverter device with which, among inverter devices each including a DC/AC inverter and the like, control of a parallel operation accompanied with an increase in power capacity or the like can be easily performed without using a control line for connecting between the inverter devices. A parallel inverter device (1) includes a switcher (15) in which, on an output line to which a load (40) is connected, two MOSFETs connected in series to the load are arranged so as to face each other so that their energization directions are opposite directions. ON/OFF of each MOSFET of the switcher (15) is controlled based on a polarity of an AC voltage output from a filter circuit (10) of the parallel inverter device (1) and a direction of a current flowing to the load (40) on the output line so that a cross current is interrupted. Further, a voltage difference or a phase difference between a load voltage and the AC voltage output from the filter circuit (10) is controlled so as to be reduced so that occurrence of the cross current is prevented.